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CASE DESCRIPTION A 9-month-old intact male domestic shorthair cat was evaluated for increasing frequency of generalized tonic-clonic seizures. CLINICAL FINDINGS The cat was reported to have had episodes of circling between the seizures. Upon examination, the cat had bilateral inconsistent menace response but otherwise normal physical and neurological examinations. DIAGNOSTICS Magnetic resonance imaging (MRI) of the brain identified multifocal, small, rounded intra-axial lesions within the subcortical white matter containing fluid with similar characteristics as cerebrospinal fluid. Evaluation of urine organic acids showed increased excretion of 2-hydroxyglutaric acid. An XM_023255678.2:c.397C>T nonsense variant in the L2HGDH gene encoding L-2-hydroxyglutarate dehydrogenase was identified using whole genome sequencing. TREATMENT AND OUTCOME Levetiracetam treatment was initiated at 20 mg/kg PO q8h, but the cat died after a seizure 10 days later. CLINICAL RELEVANCE We report the second pathogenic gene variant in L-2-hydroxyglutaric aciduria in cats and describe for the first time multicystic cerebral lesions on MRI.

BACKGROUND Some paroxysmal movement disorders remain without an identified genetic cause. OBJECTIVES The aim was to identify the causal genetic variant for a paroxysmal dystonia-ataxia syndrome in Weimaraner dogs. METHODS Clinical and diagnostic investigations were performed. Whole genome sequencing of one affected dog was used to identify private homozygous variants against 921 control genomes. RESULTS Four Weimaraners were presented for episodes of abnormal gait. Results of examinations and diagnostic investigations were unremarkable. Whole genome sequencing revealed a private frameshift variant in the TNR (tenascin-R) gene in an affected dog, XM_038542431.1:c.831dupC, which is predicted to truncate more than 75% of the open read frame. Genotypes in a cohort of 4 affected and 70 unaffected Weimaraners showed perfect association with the disease phenotype. CONCLUSIONS We report the association of a TNR variant with a paroxysmal dystonia-ataxia syndrome in Weimaraners. It might be relevant to include sequencing of this gene in diagnosing humans with unexplained paroxysmal movement disorders. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Ichthyoses represent a heterogeneous group of cornification disorders that are associated with skin barrier defects. We investigated a 9-month-old Chihuahua showing excessive scale formation. Clinical and histopathological examinations revealed non-epidermolytic ichthyosis and a genetic defect was suspected. We therefore sequenced the genome of the affected dog and compared the data with 564 genetically diverse control genomes. Filtering for private variants identified a homozygous missense variant in SDR9C7, c.454C>T or p.(Arg152Trp). SDR9C7 is a known candidate gene for ichthyosis in humans and encodes the short-chain dehydrogenase/reductase family 9C member 7. The enzyme is involved in the production of a functional corneocyte lipid envelope (CLE), a crucial component of the epidermal barrier. Pathogenic variants in SDR9C7 have been described in human patients with autosomal recessive ichthyosis. We assume that the identified missense variant in the affected Chihuahua of this study impairs the normal enzymatic activity of SDR9C7 and thus prevents the formation of a functioning CLE, resulting in a defective skin barrier. To the best of our knowledge, this is the first report of a spontaneous SDR9C7 variant in domestic animals.

Methemoglobinemia is an acquired or inherited condition resulting from oxidative stress or dysfunction of the NADH-cytochrome b5 reductase or associated pathways. This study describes the clinical, pathophysiological, and molecular genetic features of a cat with hereditary methemoglobinemia. Whole genome sequencing and mRNA transcript analyses were performed in affected and control cats. Co-oximetry, ektacytometry, Ellman’s assay for reduced glutathione concentrations, and CYB5R activity were assessed. A young adult European domestic shorthair cat decompensated at induction of anesthesia and was found to have persistent methemoglobinemia of 39 ± 8% (reference range < 3%) of total hemoglobin which could be reversed upon intravenous methylene blue injection. The erythrocytic CYB5R activity was 20 ± 6% of normal. Genetic analyses revealed a single homozygous base exchange at the beginning of intron 3 of the CYB5R3 gene, c.226+5G>A. Subsequent mRNA studies confirmed a splice defect and demonstrated expression of two mutant CYB5R3 transcripts. Erythrocytic glutathione levels were twice that of controls. Mild microcytosis, echinocytes, and multiple Ca2+-filled vesicles were found in the affected cat. Erythrocytes were unstable at high osmolarities although highly deformable as follows from the changes in elongation index and maximal-tolerated osmolarity. Clinicopathological presentation of this cat was similar to other cats with CYB5R3 deficiency. We found that methemoglobinemia is associated with an increase in red blood cell fragility and deformability, glutathione overload, and morphological alterations typical for stress erythropoiesis.

Darier disease is caused by heterozygous loss of function variants in the ATP2A2 gene encoding the endoplasmic/sarcoplasmic reticulum Ca2+ pump ATP2A2. Defective intracellular calcium signaling in the epidermis results in a loss of desmosomal adhesion and the development of characteristic skin lesions. In this study, we investigated a Shih Tzu that developed erythematous papules on the ventrum and, over time, the dorsal neck and a nodule in the right ear canal with secondary ear infection. Histopathologic examination demonstrated discrete foci of acantholysis affecting suprabasal layers of the epidermis. Whole genome sequencing of the affected dog identified a heterozygous missense variant, p.N809H, affecting an evolutionarily conserved amino acid residue of the ATP2A2 protein. The highly characteristic clinical and histopathologic findings together with a plausible variant in the only known functional candidate gene establish the diagnosis of canine Darier disease in the studied dog and highlight the potential of genetic analyses as complementary diagnostic approach in veterinary medicine.

We investigated four European domestic shorthair kittens with skin lesions consistent with the dermatosparaxis type of the Ehlers-Danlos syndrome (EDS), a connective tissue disorder. The kittens were sired by the same tomcat, but were born by three different mothers. The kittens had easily torn skin resulting in non-healing skin wounds. Both clinically and histologically, the skin showed thin epidermis in addition to inflammatory changes. Changes in collagen fibers were visible in electron micrographs. The complete genome of an affected kitten was sequenced. A one base pair duplication leading to a frameshift in the candidate gene ADAMTS2 was identified, p.(Ser235fs*3). All four affected cats carried the frameshift duplication in a homozygous state. Genotypes at this variant showed perfect co-segregation with the autosomal recessive EDS phenotype in the available family. The mutant allele did not occur in 48 unrelated control cats. ADAMTS2 loss-of-function variants cause autosomal recessive forms of EDS in humans, mice, dogs, cattle and sheep. The available evidence from our investigation together with the functional knowledge on ADAMTS2 in other species allow to classify the identified ADAMTS2 variant as pathogenic and most likely causative variant for the observed EDS.

LINE-1 is an active transposable element encoding proteins capable of inserting host gene retrocopies, resulting in retro-copy number variants (retroCNVs) between individuals. Here, we performed retroCNV discovery using 86 equids and identified 437 retrocopy insertions. Only 5 retroCNVs were shared between horses and other equids, indicating that the majority of retroCNVs inserted after the species diverged. A large number (17-35 copies) of segmentally duplicated Ligand Dependent Nuclear Receptor Corepressor Like (LCORL) retrocopies were present in all equids but absent from other extant perissodactyls. The majority of LCORL transcripts in horses and donkeys originate from the retrocopies. The initial LCORL retrotransposition occurred 18 million years ago (17-19 95% CI), which is coincident with the increase in body size, reduction in digit number, and changes in dentition that characterized equid evolution. Evolutionary conservation of the LCORL retrocopy segmental amplification in the Equidae family, high expression levels and the ancient timeline for LCORL retrotransposition support a functional role for this structural variant.

Two boxer dogs from the same litter were presented at 3 months of age for urinary and fecal incontinence. Both dogs had an abnormal tail consisting of a small stump, an atonic anal sphincter, and absent perineal reflex and sensation. Neurological evaluation was indicative of a lesion of the cauda equina or sacral spinal cord. Radiology and CT scan of the spine displayed similar findings in the two dogs that were indicative of sacral agenesis. Indeed, they had 6 lumbar vertebrae followed by a lumbosacral transitional vertebra, lacking a complete spinous process, and a hypoplastic vertebra carrying 2 hypoplastic sacral transverse processes as the only remnant of the sacral bone. Caudal vertebrae were absent in one of the dogs. On MRI, one dog had a dural sac occupying the entire spinal canal and ending in a subfascial fat structure. In the other dog, the dural sac finished in an extracanalar, subfascial, well-defined cystic structure, communicating with the subarachnoid space, and consistent with a meningocele. Sacral agenesis—that is the partial or complete absence of the sacral bones—is a neural tube defect occasionally reported in humans with spina bifida occulta. Sacral agenesis has been described in human and veterinary medicine in association with conditions such as caudal regression syndrome, perosomus elumbis, and Currarino syndrome. These neural tube defects are caused by genetic and/or environmental factors. Despite thorough genetic investigation, no candidate variants in genes with known functional impact on bone development or sacral development could be found in the affected dogs. To the best of the authors' knowledge, this is the first report describing similar sacral agenesis in two related boxer dogs.

A female Lagotto Romagnolo dog with polycystic kidney disease (PKD) and her progeny, including PKD-affected offspring, were studied. All affected dogs appeared clinically inconspicuous, while sonography revealed the presence of renal cysts. The PKD-affected index female was used for breeding and produced two litters with six affected offspring of both sexes and seven unaffected offspring. The pedigrees suggested an autosomal dominant mode of inheritance of the trait. A trio whole genome sequencing analysis of the index female and her unaffected parents identified a de novo heterozygous nonsense variant in the coding region of the PKD1 gene. This variant, NM_001006650.1:c.7195G>T, is predicted to truncate 44% of the open reading frame of the wild-type PKD1 protein, NP_001006651.1:p.(Glu2399*). The finding of a de novo variant in an excellent functional candidate gene strongly suggests that the PKD1 nonsense variant caused the observed phenotype in the affected dogs. Perfect co-segregation of the mutant allele with the PKD phenotype in two litters supports the hypothesized causality. To the best of our knowledge, this is the second description of a PKD1-related canine form of autosomal dominant PKD that may serve as an animal model for similar hepatorenal fibrocystic disorders in humans.

Canine atopic dermatitis is an inflammatory skin disease with clinical similarities to human atopic dermatitis. Several dog breeds are at increased risk for developing this disease but previous genetic associations are poorly defined. To identify additional genetic risk factors for canine atopic dermatitis, we here apply a Bayesian mixture model adapted for mapping complex traits and a cross-population extended haplotype test to search for disease-associated loci and selective sweeps in four dog breeds at risk for atopic dermatitis. We define 15 associated loci and eight candidate regions under selection by comparing cases with controls. One associated locus is syntenic to the major genetic risk locus (Filaggrin locus) in human atopic dermatitis. One selection signal in common type Labrador retriever cases positions across the TBC1D1 gene (body weight) and one signal of selection in working type German shepherd controls overlaps the LRP1B gene (brain), near the KYNU gene (psoriasis). In conclusion, we identify candidate genes, including genes belonging to the same biological pathways across multiple loci, with potential relevance to the pathogenesis of canine atopic dermatitis. The results show genetic similarities between dog and human atopic dermatitis, and future across-species genetic comparisons are hereby further motivated.

We investigated two litters of distantly related Nova Scotia Duck Tolling Retrievers (NSDTR), of which four puppies were affected by cerebellar signs with or without neuromuscular weakness. The phenotype was termed cerebellar degeneration—myositis complex (CDMC). We suspected a heritable condition and initiated a genetic analysis. The genome of one affected dog was sequenced and compared to 565 control genomes. This search yielded a private protein-changing SLC25A12 variant in the affected dog, XM_038584842.1:c.1337C>T, predicted to result in the amino acid change XP_038440770.1:(p.Pro446Leu). The genotypes at the variant co-segregated with the phenotype as expected for a monogenic autosomal recessive mode of inheritance in both litters. Genotyping of 533 additional NSDTR revealed variant allele frequencies of 3.6% and 1.3% in a European and a North American cohort, respectively. The available clinical and biochemical data, together with current knowledge about SLC25A12 variants and their functional impact in humans, mice, and dogs, suggest the p.Pro446Leu variant is a candidate causative defect for the observed phenotype in the affected dogs.

International audience; Ehlers-Danlos syndrome (EDS) is a group of heterogeneous, rare diseases affecting the connective tissues. The main clinical signs of EDS are skin hyperextensibility, joint hypermobility, and skin fragility. Currently, the classification of EDS in humans distinguishes 13 clinical subtypes associated with variants in 20 different genes, reflecting the heterogeneity of this set of diseases. At present, variants in three of these genes have also been identified in dogs affected by EDS. The purpose of this study was to characterize the clinical and histopathological phenotype of an EDS-affected Chihuahua and to identify the causative genetic variant for the disease. The clinical examination suggested a diagnosis of classical EDS. Skin histopathology revealed an abnormally thin dermis, which is compatible with classical EDS. Whole-genome sequencing identified a heterozygous de novo 27 bp deletion in the COL5A2 gene, COL5A2:c.3388_3414del. The in-frame deletion is predicted to remove 9 amino acids in the triple-helical region of COL5A2. The molecular analysis and identification of a likely pathogenic variant in COL5A2 confirmed the subtype as a form of classical EDS. This is the first report of a COL5A2-related EDS in a dog.

A 3-year-old, male neutered Cavalier King Charles Spaniel (CKCS) presented with complex focal seizures and prolonged lethargy. The aim of the study was to investigate the clinical signs, metabolic changes and underlying genetic defect. Blood and urine organic acid analysis revealed increased medium-chain fatty acids and together with the clinical findings suggested a diagnosis of medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. We sequenced the genome of the affected dog and compared the data to 923 control genomes of different dog breeds. The ACADM gene encoding MCAD was considered the top functional candidate gene. The genetic analysis revealed a single homozygous private protein-changing variant in ACADM in the affected dog. This variant, XM_038541645.1:c.444_445delinsGTTAATTCTCAATATTGTCTAAGAATTATG, introduces a premature stop codon and is predicted to result in truncation of ~63% of the wild type MCAD open reading frame, XP_038397573.1:p.(Thr150Ilefs*6). Targeted genotyping of the variant in 162 additional CKCS revealed a variant allele frequency of 23.5% and twelve additional homozygous mutant dogs. The acylcarnitine C8/C12 ratio was elevated ~43.3 fold in homozygous mutant dogs as compared to homozygous wild type dogs. Based on available clinical and biochemical data together with current knowledge in humans, we propose the ACADM frameshift variant as causative variant for the MCAD deficiency with likely contribution to the neurological phenotype in the index case. Testing the CKCS breeding population for the identified ACADM variant is recommended to prevent the unintentional breeding of dogs with MCAD deficiency. Further prospective studies are warranted to assess the clinical consequences of this enzyme defect.

Regenerating islet-derived protein (REG) 1A (aka pancreatic stone protein) and REG3A (aka pancreatitis-associated protein) are upregulated in humans with sepsis, pancreatitis, and gastrointestinal diseases, but little is known about this protein family in dogs. Our aim was to identify REG1 and REG3 family members in dogs. REG-family genes were computationally annotated in the canine genome and proteome, with verification of gene expression using publicly available RNA-seq data. The presence of the protein in canine pancreatic tissue and plasma was investigated with Western blot and immunohistochemistry, using anti-human REG1A and REG3A antibodies. Protein identity was confirmed with mass spectrometry. Two members of the REG3 subfamily were found in the canine genome, REG3E1 and REG3E2, both encoding for the same 176 AA protein, subsequently named REG3E. Anti-human REG3A antibodies demonstrated cross-reactivity with the canine REG3E protein in pancreas homogenates. In canine plasma, a protein band of approximately 17 kDa was apparent. Mass spectrometry confirmed this protein to be the product of the two annotated REG3E genes. Strong immunoreactivity to anti-human REG3A antibodies was found in sections of canine pancreas affected with acute pancreatitis, but it was weak in healthy pancreatic tissue. Recombinant canine REG3E protein underwent a selective trypsin digestion as described in other species. No evidence for the presence of a homolog of REG1A in dogs was found in any of the investigations. In conclusion, dogs express REG3E in the pancreas, whose role as biomarker merits further investigations. Homologs to human REG1A are not likely to exist in dogs.

Ichthyoses are hereditary skin disorders characterized by the formation of scales and defects in the outermost layer of the epidermis. In dogs, at least six different breed-specific ichthyoses including a relatively common PNPLA1-related autosomal recessive ichthyosis in Golden Retrievers are known. In this study, we investigated 14 Golden Retrievers with scales that were not homozygous for the mutant PNPLA1 allele suggesting a genetically distinct new form of ichthyosis. Histopathological examinations showed lamellar, orthokeratotic hyperkeratosis, and mildly hyperplastic epidermis that led to the diagnosis of a nonepidermolytic ichthyosis. Combined linkage and homozygosity mapping in 14 cases and 30 nonaffected family members delimited a critical interval of ∼12.7 Mb on chromosome 23. Whole-genome sequencing of an affected dog revealed a single protein-changing variant within this region that was not present in 795 control genomes. The identified variant is a 14 bp deletion in the ABHD5 gene (c.1006_1019del), leading to a frameshift and altering the last 14 codons p.(Asp336Serfs*6). The genotypes at this variant showed perfect cosegregation with the ichthyosis phenotype in a large family comprising 14 cases and 72 controls. ABHD5 encodes an acyltransferase required for lipid metabolism. In humans, variants in ABHD5 cause Chanarin-Dorfman syndrome, a neutral lipid storage disease with ichthyosis. Our data in dogs together with the knowledge on the effects of ABHD5 variants in humans strongly suggest ABHD5:c.1006_1019del as candidate causative genetic variant for a new canine form of ichthyosis, which we propose to designate as Golden Retriever ichthyosis type 2 (ICH2).

We investigated four cats with similar clinical skin-related signs strongly suggestive of Ehlers-Danlos syndrome (EDS). Cases no. 1 and 4 were unrelated and the remaining two cases, no. 2 and 3, were reportedly siblings. Histopathological changes were characterized by severely altered dermal collagen fibers. Transmission electron microscopy in one case demonstrated abnormalities in the collagen fibril organization and structure. The genomes of the two unrelated affected cats and one of the affected siblings were sequenced and individually compared to 54 feline control genomes. We searched for private protein changing variants in known human EDS candidate genes and identified three independent heterozygous COL5A1 variants. COL5A1 is a well-characterized candidate gene for classical EDS. It encodes the proα1 chain of type V collagen, which is needed for correct collagen fibril formation and the integrity of the skin. The identified variants in COL5A1 are c.112_118+15del or r.spl?, c.3514A>T or p.(Lys1172*), and c.3066del or p.(Gly1023Valfs*50) for cases no. 1, 2&3, and 4, respectively. They presumably all lead to nonsense-mediated mRNA decay, which results in haploinsufficiency of COL5A1 and causes the alterations of the connective tissue. The whole genome sequencing approach used in this study enables a refinement of the diagnosis for the affected cats as classical EDS. It further illustrates the potential of such experiments as a precision medicine approach in animals with inherited diseases.

The transcriptomic profile of a cell population can now be studied at the cellular level using single-cell mRNA sequencing (scRNA-seq). This novel technique provides the unprecedented opportunity to explore the cellular composition of the bronchoalveolar lavage fluid (BALF) of the horse, a species for which cell type markers are poorly described. Here, scRNA-seq technology was applied to cryopreserved equine BALF cells. Analysis of 4,631 cells isolated from three asthmatic horses in remission identified 16 cell clusters belonging to six major cell types: monocytes/macrophages, T cells, B/plasma cells, dendritic cells, neutrophils and mast cells. Higher resolution analysis of the constituents of the major immune cell populations allowed deep annotation of monocytes/macrophages, T cells and B/plasma cells. A significantly higher lymphocyte/macrophage ratio was detected with scRNA-seq compared to conventional cytological differential cell count. For the first time in horses, we detected a transcriptomic signature consistent with monocyte-lymphocyte complexes. Our findings indicate that scRNA-seq technology is applicable to cryopreserved equine BALF cells, allowing the identification of its major (cytologically differentiated) populations as well as previously unexplored T cell and macrophage subpopulations. Single-cell gene expression analysis has the potential to facilitate understanding of the immunological mechanisms at play in respiratory disorders of the horse, such as equine asthma.

Domestication of wild animal and plant species may be considered the largest genetic experiment in human history. Human selection for specific traits and targeted breeding over hundreds or thousands of generations has shaped very special populations that provide unique opportunities for research. Domestic animal genetics contributes to technological advances facilitating a more sustainable, environment- and climate-friendly food production that respects changing societal expectations related to ethical and animal welfare issues. Domestic animal genetics also enables fundamental insights into gene functions and provides animal models for biomedical research. In this collection, curated by Associate Editor Tosso Leeb, we present a selection of PLOS Genetics research that exemplifies recent progress in domestic animal genetics and areas for future development.

We investigated a hereditary syndrome in Cane Corso dogs. Affected dogs developed dental-skeletal-retinal anomaly (DSRA), clinically characterized by brittle, discolored, translucent teeth, disproportionate growth and progressive retinal degeneration resulting in vision loss. Combined linkage and homozygosity mapping delineated a 5.8 Mb critical interval. The comparison of whole genome sequence data of an affected dog to 789 control genomes revealed a private homozygous splice region variant in the critical interval. It affected the MIA3 gene encoding the MIA SH3 domain ER export factor 3, which has an essential role in the export of collagen and other secreted proteins. The identified variant, XM_005640835.3:c.3822+3_3822+4del, leads to skipping of two exons from the wild type transcript, XM_005640835.3:r.3712_3822del. Genotypes at the variant were consistent with monogenic autosomal recessive mode of inheritance in a complete family and showed perfect genotype-phenotype association in 18 affected and 22 unaffected Cane Corso dogs. MIA3 variants had previously been shown to cause related phenotypes in humans and mice. Our data in dogs together with the existing functional knowledge of MIA3 variants in other mammalian species suggest the MIA3 splice defect and a near complete loss of gene function as causative molecular pathomechanism for the DSRA phenotype in the investigated dogs.

A 1-month-old, female, smooth-haired miniature Dachshund with dilute color and neurological defects was investigated. The aim of this study was to characterize the clinical signs, histopathological changes and underlying genetic defect. The puppy had visible coat color dilution and was unable to hold its head on its own or to remain in a stable prone position for an extended period. Histopathological examination revealed an accumulation of clumped melanin and deposition of accumulated keratin within the hair follicles, accompanied by dermal pigmentary incontinence. These dermatological changes were compatible with the histopathology described in dogs with an MLPH-related dilute coat color. We sequenced the genome of the affected dog and compared the data to 795 control genomes. MYO5A, coding for myosin VA, was investigated as the top functional candidate gene. This search revealed a private homozygous frameshift variant in MYO5A, XM_022412522.1:c.4973_4974insA, predicted to truncate 269 amino acids (13.8%) of the wild type myosin VA protein, XP_022268230.1:p.(Asn1658Lysfs*28). The genotypes of the index family showed the expected co-segregation with the phenotype and the mutant allele was absent from 142 additionally genotyped, unrelated Dachshund dogs. MYO5A loss of function variants cause Griscelli type 1 syndrome in humans, lavender foal in horses and the phenotype of the dilute mouse mutant. Based on the available data, together with current knowledge on other species, we propose the identified MYO5A frameshift insertion as a candidate causative variant for the observed dermatological and neurological signs in the investigated dog.

In a litter of Turkish Van cats, three out of six kittens developed severe signs of skin disease, diarrhea, and systemic signs of stunted growth at 6 weeks of age. Massive secondary infections of the skin lesions evolved. Histopathological examinations showed a mild to moderate hyperplastic epidermis, covered by a thick layer of laminar to compact, mostly parakeratotic keratin. The dermis was infiltrated with moderate amounts of lymphocytes and plasma cells. Due to the severity of the clinical signs, one affected kitten died and the other two had to be euthanized. We sequenced the genome of one affected kitten and compared the data to 54 control genomes. A search for private variants in the two candidate genes for the observed phenotype, MKLN1 and SLC39A4, revealed a single protein-changing variant, SLC39A4:c.1057G&gt, C or p.Gly353Arg. The solute carrier family 39 member 4 gene (SLC39A4) encodes an intestinal zinc transporter required for the uptake of dietary zinc. The variant is predicted to change a highly conserved glycine residue within the first transmembrane domain, which most likely leads to a loss of function. The genotypes of the index family showed the expected co-segregation with the phenotype and the mutant allele was absent from 173 unrelated control cats. Together with the knowledge on the effects of SLC39A4 variants in other species, these data suggest SLC39A4:c.1057G&gt, C as candidate causative genetic variant for the phenotype in the investigated kittens. In line with the human phenotype, we propose to designate this disease acrodermatitis enteropathica (AE).

An international team of researchers including scientists from the Institute of Genetics of the University of Bern has unraveled the enigma of inheritance of coat color patterns in dogs. The researchers discovered that a genetic variant responsible for a very light coat in dogs and wolves originated more than two million years ago in a now extinct relative of the modern wolf., Ein internationales Konsortium von Forschenden mit Beteiligung des Instituts für Genetik der Universität Bern konnte zeigen, wie Fellfarben bei Hunden vererbt werden. Zudem konnten sie nachweisen, dass eine Genvariante für helles Fell bei Hunden und Wölfen von einem inzwischen ausgestorbenen Verwandten des Wolfs stammt und mehr als zwei Millionen Jahre alt ist.

Distinctive colour patterns in dogs are an integral component of canine diversity. Colour pattern differences are thought to have arisen from mutation and artificial selection during and after domestication from wolves but important gaps remain in understanding how these patterns evolved and are genetically controlled. In other mammals, variation at the ASIP gene controls both the temporal and spatial distribution of yellow and black pigments. Here, we identify independent regulatory modules for ventral and hair cycle ASIP expression, and we characterize their action and evolutionary origin. Structural variants define multiple alleles for each regulatory module and are combined in different ways to explain five distinctive dog colour patterns. Phylogenetic analysis reveals that the haplotype combination for one of these patterns is shared with Arctic white wolves and that its hair cycle-specific module probably originated from an extinct canid that diverged from grey wolves more than 2 million years ago. Natural selection for a lighter coat during the Pleistocene provided the genetic framework for widespread colour variation in dogs and wolves., Dogs exhibit remarkable variation in colour patterns. Here, the authors identify structural variants of independent regulatory modules for ventral and hair cycle expression of the ASIP gene that explain five distinctive dog colour patterns and trace back the origin of one colour pattern to an extinct canid.

Equine insect bite hypersensitivity (IBH) is the most common skin disease affecting horses. It is described as an IgE-mediated, Type I hypersensitivity reaction to salivary gland proteins of Culicoides insects. Together with Th2 cells, epithelial barrier cells play an important role in development of Type I hypersensitivities. In order to elucidate the role of equine keratinocytes in development of IBH, we stimulated keratinocytes derived from IBH-affected (IBH-KER) (n = 9) and healthy horses (H-KER) (n = 9) with Culicoides recombinant allergens and extract, allergic cytokine milieu (ACM) and a Toll like receptor ligand 1/2 (TLR-1/2-L) and investigated their transcriptomes. Stimulation of keratinocytes with Culicoides allergens did not induce transcriptional changes. However, when stimulated with allergic cytokine milieu, their gene expression significantly changed. We found upregulation of genes encoding for CCL5, -11, -20, -27 and interleukins such as IL31. We also found a strong downregulation of genes such as SCEL and KRT16 involved in the formation of epithelial barrier. Following stimulation with TLR-1/2-L, keratinocytes significantly upregulated expression of genes affecting Toll like receptor and NOD-receptor signaling pathway as well as NF-kappa B signaling pathway, among others. The transcriptomes of IBH-KER and H-KER were very similar: without stimulations they only differed in one gene (CTSL); following stimulation with allergic cytokine milieu we found only 23 differentially expressed genes (e.g. CXCL10 and 11) and following stimulation with TLR-1/2-L they only differed by expression of seven genes. Our data suggests that keratinocytes contribute to the innate immune response and are able to elicit responses to different stimuli, possibly playing a role in the pathogenesis of IBH.

X-linked hypohidrotic ectodermal dysplasia-1 (ECTD1) in people results in a spectrum of abnormalities, most importantly hypotrichosis, anodontia/oligodontia, and absent or defective ectodermally derived glands. Five Red Angus-Simmental calves born over a 6-year period demonstrated severe hypotrichosis and were diagnosed as affected with ECTD1-like syndrome. Two died of severe pneumonia within a week of birth. The skin of three affected calves revealed a predominance of histologically unremarkable small-caliber hair follicles. Larger follicles (&gt, 50 µm) containing medullated hairs (including guard and tactile hairs) were largely restricted to the muzzle, chin, tail, eyelids, tragus and distal portions of the limbs and tail. The mean histological density of hair follicles in flank skin of two affected calves was slightly greater than that in two unaffected calves. One affected calf was examined postmortem at 10 days of age to better characterize systemic lesions. Nasolabial, intranasal and tracheobronchial mucosal glands were absent, whereas olfactory glands were unaffected. Mandibular incisor teeth were absent. Premolar teeth were unerupted and widely spaced. Other than oligodontia, histological changes in teeth were modest, featuring multifocal disorganization of ameloblasts, new bone formation in dental alveoli, and small aggregates of osteodentin and cementum at the margins of the enamel organ. A 52,780 base pair deletion spanning six out of eight coding exons of EDA and all of AWAT2 was identified. Partial deletion of the EDA gene is the presumed basis for the reported X-chromosomal recessive inherited genodermatosis.

Canine cutaneous epitheliotropic T-cell lymphoma (CETL) and immune-mediated T-cell predominant dermatoses (IMD) share several clinical and histopathological features, but differ substantially in prognosis. The discrimination of ambiguous cases may be challenging, as diagnostic tests are limited and may prove equivocal. This study aimed to investigate transcriptional differences between CETL and IMD, as a basis for further research on discriminating diagnostic biomarkers. We performed 100bp single-end sequencing on RNA extracted from formalin-fixed and paraffin-embedded skin biopsies from dogs with CETL and IMD, respectively. DESeq2 was used for principal component analysis (PCA) and differential gene expression analysis. Genes with significantly different expression were analyzed for enriched pathways using two different tools. The expression of selected genes and their proteins was validated by RT-qPCR and immunohistochemistry. PCA demonstrated the distinct gene expression profiles of CETL and IMD. In total, 503 genes were upregulated, while 4986 were downregulated in CETL compared to IMD. RT-qPCR confirmed the sequencing results for 5/6 selected genes tested, while the protein expression detected by immunohistochemistry was not entirely consistent. Our study revealed transcriptional differences between canine CETL and IMD, with similarities to human cutaneous lymphoma. Differentially expressed genes are potential discriminatory markers, but require further validation on larger sample collections.

An international team of researchers including scientists from the Institute of Genetics of the University of Bern has unraveled the enigma of inheritance of coat color patterns in dogs. The researchers discovered that a genetic variant responsible for a very light coat in dogs and wolves originated more than two million years ago in a now extinct relative of the modern wolf.

Dwarfism phenotypes occur in many species and may be caused by genetic or environmental factors. In this study, we investigated a family of nine Dogo Argentino dogs, in which two dogs were affected by disproportionate dwarfism. Radiographs of an affected dog revealed a decreased level of endochondral ossification in its growth plates, and a premature closure of the distal ulnar physes. The pedigree of the dogs presented evidence of monogenic autosomal recessive inheritance, combined linkage and homozygosity mapping assigned the most likely position of a potential genetic defect to 34 genome segments, totaling 125 Mb. The genome of an affected dog was sequenced and compared to 795 control genomes. The prioritization of private variants revealed a clear top candidate variant for the observed dwarfism. This variant, PRKG2:XM_022413533.1:c.1634+1G&gt, T, affects the splice donor site and is therefore predicted to disrupt the function of the PKRG2 gene encoding protein, kinase cGMP-dependent type 2, a known regulator of chondrocyte differentiation. The genotypes of the PRKG2 variant were perfectly associated with the phenotype in the studied family of dogs. PRKG2 loss-of-function variants were previously reported to cause disproportionate dwarfism in humans, cattle, mice, and rats. Together with the comparative data from other species, our data strongly suggest PRKG2:c.1634+1G&gt, T to be a candidate causative variant for the observed dwarfism phenotype in Dogo Argentino dogs.

The Valais Blackneck goat is a Swiss goat breed with a characteristic coat color phenotype. Before the revision of the breed standard in 1938, 4 different color varieties of Valais goats were known. Besides Blackneck animals resembling the modern breed standard, the brown and white Copperneck goat, the white Capra Sempione, and the greyish Grüenochte comprised the historic Valais goats. The brown pigmentation of Copperneck goats had previously been traced back to an introgression of a mutant TYRP1 allele from Toggenburg goats. In the present study, we identified additional introgression events of distinct ASIP alleles causing the remaining 2 rare coat color patterns within the Valais Blackneck goat breed. We identified the introgression of the AWt allele from Appenzell or Saanen goats in white Capra Sempione goats. Similarly, introgression of the Apc allele from Peacock goats resulted in the greyish Grüenochte phenotype. These results demonstrate past hybridization events between breeds that are separated today. A perfect genotype-phenotype association in 393 Valais goats supported the causality of the genotyped variants for the different coat color phenotypes. Our study gives insights into the introgression of functionally relevant copy number variant (CNV) alleles controlling pigmentation between goat breeds with strikingly different coat color patterns.

In a highly inbred Australian Shepherd litter, three of the five puppies developed widespread ulcers of the skin, footpads, and oral mucosa within the first weeks of life. Histopathological examinations demonstrated clefting of the epidermis from the underlying dermis within or just below the basement membrane, which led to a tentative diagnosis of junctional epidermolysis bullosa (JEB) with autosomal recessive inheritance. Endoscopy in one affected dog also demonstrated separation between the epithelium and underlying tissue in the gastrointestinal tract. As a result of the severity of the clinical signs, all three dogs had to be euthanized. We sequenced the genome of one affected puppy and compared the data to 73 control genomes. A search for private variants in 37 known candidate genes for skin fragility phenotypes revealed a single protein-changing variant, LAMB3:c.1174T&gt, C, or p.Cys392Arg. The variant was predicted to change a conserved cysteine in the laminin &beta, 3 subunit of the heterotrimeric laminin-322, which mediates the binding of the epidermal basement membrane to the underlying dermis. Loss-of-function variants in the human LAMB3 gene lead to recessive forms of JEB. We confirmed the expected co-segregation of the genotypes in the Australian Shepherd family. The mutant allele was homozygous in two genotyped cases and heterozygous in three non-affected close relatives. It was not found in 242 other controls from the Australian Shepherd breed, nor in more than 600 other controls. These data suggest that LAMB3:c.1174T&gt, C represents the causative variant. To the best of our knowledge, this study represents the first report of a LAMB3-related JEB in domestic animals.

Four female Shetland Sheepdogs with hypertonic paroxysmal dyskinesia, mainly triggered by exercise and stress, were investigated in a retrospective multi-center investigation aiming to characterize the clinical phenotype and its underlying molecular etiology. Three dogs were closely related and their pedigree suggested autosomal dominant inheritance. Laboratory diagnostic findings included mild lactic acidosis and lactaturia, mild intermittent serum creatine kinase (CK) elevation and hypoglycemia. Electrophysiological tests and magnetic resonance imaging of the brain were unremarkable. A muscle/nerve biopsy revealed a mild type II fiber predominant muscle atrophy. While treatment with phenobarbital, diazepam or levetiracetam did not alter the clinical course, treatment with a gluten-free, home-made fresh meat diet in three dogs or a tryptophan-rich, gluten-free, seafood-based diet, stress-reduction, and acetazolamide or zonisamide in the fourth dog correlated with a partial reduction in, or even a complete absence of, dystonic episodes. The genomes of two cases were sequenced and compared to 654 control genomes. The analysis revealed a case-specific missense variant, c.1658G&gt, A or p.Arg553Gln, in the PCK2 gene encoding the mitochondrial phosphoenolpyruvate carboxykinase 2. Sanger sequencing confirmed that all four cases carried the mutant allele in a heterozygous state. The mutant allele was not found in 117 Shetland Sheepdog controls and more than 500 additionally genotyped dogs from various other breeds. The p.Arg553Gln substitution affects a highly conserved residue in close proximity to the GTP-binding site of PCK2. Taken together, we describe a new form of paroxysmal exercise-induced dyskinesia (PED) in dogs. The genetic findings suggest that PCK2:p.Arg553Gln should be further investigated as putative candidate causal variant.

Brown or chocolate coat color in many mammalian species is frequently due to variants at the B locus or TYRP1 gene. In dogs, five different TYRP1 loss-of-function alleles have been described, which explain the vast majority of dogs with brown coat color. Recently, breeders and genetic testing laboratories identified brown French Bulldogs that did not carry any of the known mutant TYRP1 alleles. We sequenced the genome of a TYRP1+/+ brown French Bulldog and compared the data to 655 other canine genomes. A search for private variants revealed a nonsense variant in HPS3, c.2420G&gt, A or p.(Trp807*). The brown dog was homozygous for the mutant allele at this variant. The HPS3 gene encodes a protein required for the correct biogenesis of lysosome-related organelles, including melanosomes. Variants in the human HPS3 gene cause Hermansky&ndash, Pudlak syndrome 3, which involves a mild form of oculocutaneous albinism and prolonged bleeding time. A variant in the murine Hps3 gene causes brown coat color in the cocoa mouse mutant. We genotyped a cohort of 373 French Bulldogs and found a strong association of the homozygous mutant HPS3 genotype with the brown coat color. The genotype&ndash, phenotype association and the comprehensive knowledge on HPS3 function from other species strongly suggests that HPS3:c.2420G&gt, A is the causative variant for the observed brown coat color in French Bulldogs. In order to clearly distinguish HPS3-related from the TYRP1-related brown coat color, and in line with the murine nomenclature, we propose to designate this dog phenotype as &ldquo, cocoa&rdquo, and the mutant allele as HPS3co.

A 4-month-old female Irish Terrier presented with a well demarcated ulcerative and crusting lesion in the right ear canal. Histological analysis revealed epidermal hyperplasia with severe acantholysis affecting all suprabasal layers of the epidermis, which prompted a presumptive diagnosis of canine Darier disease. The lesion was successfully treated by repeated laser ablation of the affected epidermis. Over the course of three years, the dog additionally developed three dermal nodules of up to 4 cm in diameter that were excised and healed without complications. Histology of the excised tissue revealed multiple infundibular cysts extending from the upper dermis to the subcutis. The cysts were lined by squamous epithelium, which presented with abundant acantholysis of suprabasal keratinocytes. Infundibular cysts represent a novel finding not previously reported in Darier patients. Whole genome sequencing of the affected dog was performed, and the functional candidate genes for Darier disease (ATP2A2) and Hailey-Hailey disease (ATP2C1) were investigated. The analysis revealed a heterozygous SINE insertion into the ATP2A2 gene, at the end of intron 14, close to the boundary of exon 15. Analysis of the ATP2A2 mRNA from skin of the affected dog demonstrated a splicing defect and marked allelic imbalance, suggesting nonsense-mediated decay of the resulting aberrant transcripts. As Darier disease in humans is caused by haploinsufficiency of ATP2A2, our genetic findings are in agreement with the clinical and histopathological data and support the diagnosis of canine Darier disease.

A single male Rottweiler dog with severe footpad hyperkeratosis starting at an age of eight weeks was investigated. The hyperkeratosis was initially restricted to the footpads. The footpad lesions caused severe discomfort to the dog and had to be trimmed under anesthesia every 8&ndash, 10 weeks. Histologically, the epidermis showed papillated villous projections of dense keratin in the stratum corneum. Starting at eight months of age, the patient additionally developed signs consistent with atopic dermatitis and recurrent bacterial skin and ear infections. Crusted hyperkeratotic plaques developed at sites of infection. We sequenced the genome of the affected dog and compared the data to 655 control genomes. A search for variants in 32 candidate genes associated with human palmoplantar keratoderma (PPK) revealed a single private protein-changing variant in the affected dog. This was located in the DSG1 gene encoding desmoglein 1. Heterozygous monoallelic DSG1 variants have been reported in human patients with striate palmoplantar keratoderma I (SPPK1), while biallelic DSG1 loss of function variants in humans lead to a more pronounced condition termed severe dermatitis, multiple allergies, and metabolic wasting (SAM) syndrome. The identified canine variant, DSG1:c.2541_2545delGGGCT, leads to a frameshift and truncates about 20% of the coding sequence. The affected dog was homozygous for the mutant allele. The comparative data on desmoglein 1 function in humans suggest that the identified DSG1 variant may have caused the footpad hyperkeratosis and predisposition for allergies and skin infections in the affected dog.

Goat domestication and human selection for valued traits have formed diverse breeds with characteristic phenotypes. This process led to the fixation of causative genetic variants controlling breed-specific traits within regions of reduced genetic diversity—so-called “selection signatures”. We previously reported an analysis of selection signatures based on pooled whole-genome sequencing data of 20 goat breeds and bezoar goats. In the present study, we reanalyzed the data and focused on a subset of eight Pakistani goat breeds (Angora, Barbari, Beetal, Dera Din Panah, Kamori, Nachi, Pahari, Teddy). We identified 749 selection signatures based on reduced heterozygosity in these breeds. A search for signatures that are shared across large-sized goat breeds revealed that five medium-to-large-sized Pakistani goat breeds had a common selection signature on chromosome 6 in a region harboring the LCORL gene, which has been shown to modulate height or body size in several mammalian species. Fine-mapping of the region confirmed that all five goat breeds with the selection signature were nearly fixed for the same haplotype in a ~191 kb region spanning positions 37,747,447−37,938,449. From the pool sequencing data, we identified a frame-shifting single base insertion into an isoform-specific exon of LCORL as a potential candidate causal variant mediating the size-increasing effect. If this preliminary result can be confirmed in independent replication studies, genotyping of this variant might be used to improve breeding programs and the selection for stature in goats.

Insect bite hypersensitivity (IBH) is a Th-2, IgE-mediated dermatitis of horses caused by bites of insects of the genus Culicoides that has common features with human atopic dermatitis. Together with Th-2 cells, the epithelial barrier plays an important role in development of type I hypersensitivities. In order to elucidate the role of the epithelial barrier and of the skin immune response in IBH we studied the transcriptome of lesional whole skin of IBH-horses (IBH-LE; n = 9) in comparison to non-lesional skin (IBH-NL; n = 8) as well as to skin of healthy control horses (H; n = 9). To study the "baseline state" of the epithelial barrier, we investigated the transcriptome of non-lesional epidermis in IBH-horses (EPI-IBH-NL; n = 10) in comparison with healthy epidermis from controls (EPI-H; n = 9). IBH-LE skin displayed substantial transcriptomic difference compared to H. IBH-LE was characterized by a downregulation of genes involved in tight junction formation, alterations in keratins and substantial immune signature of both Th-1 and Th-2 types with particular upregulation of IL13, as well as involvement of the hypoxic pathway. IBH-NL shared a number of differentially expressed genes (DEGs) with IBH-LE, but was overall more similar to H skin. In the epidermis, genes involved in metabolism of epidermal lipids, pruritus development, as well as IL25, were significantly differentially expressed between EPI-IBH-NL and EPI-H. Taken together, our data suggests an impairment of the epithelial barrier in IBH-affected horses that may act as a predisposing factor for IBH development. Moreover, these new mechanisms could potentially be used as future therapeutic targets. Importantly, many transcriptional features of equine IBH skin are shared with human atopic dermatitis, confirming equine IBH as a natural model of skin allergy.

Purebred dog breeds provide a powerful resource for the discovery of genetic variants affecting skeletal morphology. Domesticated and subsequently purebred dogs have undergone strong artificial selection for a broad range of skeletal variation, which include both the size and shapes of their bones. While the phenotypic variation between breeds is high, within-breed morphological variation is typically low. Approaches for defining genetic variants associated with canine morphology include quantitative within-breed analyses, as well as across-breed analyses, using breed standards as proxies for individual measurements. The ability to identify variants across the genomes of individual dogs can now be paired with precise measures of morphological variation to define the genetic interactions and the phenotypic effect of variants on skeletal morphology.

WOS: 000512336600034, PubMed: 31841508, Domestication and human selection have formed diverse goat breeds with characteristic phenotypes. This process correlated with the fixation of causative genetic variants controlling breed-specific traits within regions of reduced genetic diversity, so called selection signatures or selective sweeps. Using whole genome sequencing of DNA pools (pool-seq) from 20 genetically diverse modern goat breeds and bezoars, we identified 2,239 putative selection signatures. In two Pakistani goat breeds, Pak Angora and Barbari, we found selection signatures in a region harboring KIT, a gene involved in melanoblast development, migration, and survival. The search for candidate causative variants responsible for these selective sweeps revealed two different copy number variants (CNVs) downstream of KIT that were exclusively present in white Pak Angora and white-spotted Barbari goats. Several Swiss goat breeds selected for specific coat colors showed selection signatures at the ASIP locus encoding the agouti signaling protein. Analysis of these selective sweeps revealed four different CNVs associated with the white or tan (A(Wt)), Swiss markings (A(sm)), badger-face (A(b)), and the newly proposed peacock (A(pc)) allele. RNA-seq analyses on skin samples from goats with the different CNV alleles suggest that the identified structural variants lead to an altered expression of ASIP between eumelanistic and pheomelanistic body areas. Our study yields novel insights into the genetic control of pigmentation by identifying six functionally relevant CNVs. It illustrates how structural changes of the genome have contributed to phenotypic evolution in domestic goats., Swiss National Science FoundationSwiss National Science Foundation (SNSF) [31003A_172964]; Swiss Government Excellence Scholarship; Hans Sigrist Foundation, This study was funded by a grant from the Swiss National Science Foundation (31003A_172964). R.S. was supported by a Swiss Government Excellence Scholarship and a supplementary grant from the Hans Sigrist Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Naked foal syndrome (NFS) is a genodermatosis in the Akhal-Teke horse breed. We provide the first scientific description of this phenotype. Affected horses had almost no hair and showed a mild ichthyosis. So far, all known NFS affected horses died between a few weeks and 3 years of age. It is not clear whether a specific pathology caused the premature deaths. NFS is inherited as a monogenic autosomal recessive trait. We mapped the disease causing genetic variant to two segments on chromosomes 7 and 27 in the equine genome. Whole genome sequencing of two affected horses, two obligate carriers, and 75 control horses from other breeds revealed a single non-synonymous genetic variant on the chromosome 7 segment that was perfectly associated with NFS. The affected horses were homozygous for ST14:c.388G>T, a nonsense variant that truncates more than 80% of the open reading frame of the ST14 gene (p.Glu130*). The variant leads to partial nonsense mediated decay of the mutant transcript. Genetic variants in the ST14 gene are responsible for autosomal recessive congenital ichthyosis 11 in humans. Thus, the identified equine ST14:c.388G>T variant is an excellent candidate causative variant for NFS and the affected horses represent a large animal model for a known human genodermatosis. Our findings will enable genetic testing to avoid the non-intentional breeding of NFS affected foals.

OBJECTIVE Exercise induced metabolic myopathy in German Hunting Terrier dogs is an autosomal-recessively inherited disorder, caused by a nonsense variant of the gene encoding for the very long-chain acyl-CoA-dehydrogenase (VLCAD) enzyme. Clinical signs include exercise- induced fatigue, muscle pain and weakness. In the present study, the long-term course of this disease was investigated over a period of 1 year in 9 affected German Hunting Terriers. The dogs were treated symptomatically with oral L-carnitine, coenzyme Q10 and a special diet characterized by a low content of long-chain fatty acids and a high proportion of carbohydrates. MATERIAL AND METHODS In 9 affected dogs, the phenotype as well as clinical, laboratory parameters, and histopathological findings are described (time point 1) and compared to follow-up examinations 1 year later (time point 2). At both time points clinical and neurological examinations, complete blood cell count, clinical chemistry profile and the concentration of brain natriuretic peptide (NT-proBNP) were investigated. RESULTS In the follow-up examinations, the same post-exercise clinical signs were present as in the initial presentation of the homozygous dogs. Dark-brownish discoloration of the urine, weakness, myalgia as well as stiff and tetraparetic gait were apparant. All hematological values and the concentration of NT-proBNP were within the relevant reference ranges. Plasma CK and ALT activities were compared between the first presentation and the follow- up examination and no significant differences were detected (pCK = 0.31, pALT = 0.64). Signs of myopathy remained unchanged throughout the examination period. CONCLUSION AND CLINICAL RELEVANCE Oral supplementation with L-carnitine, coenzyme Q10 and the special dietary management did not result in any improvement of clinical signs or laboratory parameters. No progression of the disease was observed. The prognosis for affected dogs remains cautious as long-term observations of affected dogs over several years are lacking. Our findings provide further important information on inherited disorders of mitochondrial β-oxidation in dogs, especially focused on the exercise induced metabolic myopathy in the German Hunting Terrier. This may provide new insights for novel treatment modalities in conjuntion with the development of improved breeding guidelines., Gegenstand und Ziel Die belastungsabhängige metabolische Myopathie beim Deutschen Jagdterrier ist eine autosomal-rezessive Erbkrankheit, die aufgrund einer Punktmutation zu einem Enzymdefekt der sehr langkettigen Acyl-CoA-Dehydrogenase führt und klinisch durch belastungsabhängige Schwäche, schwere Myalgien und Myoglobinurie charakterisiert ist. In dieser Studie wurde der klinische Verlauf der Erkrankung bei 9 betroffenen Deutschen Jagdterriern über 1 Jahr untersucht. Die Behandlung der Hunde umfasste die orale Supplementierung von L-Carnitin und Koenzym Q10 sowie eine Diät mit hohem Kohlenhydratgehalt und einem niedrigen Anteil an langkettigen Fettsäuren. Material und Methode Die 9 Hunde mit nachgewiesenem Gendefekt wurden bei Auftreten der ersten Symptome (Messzeitpunkt 1, MZP1) und 1 Jahr später (Messzeitpunkt 2, MZP2) klinisch-neurologisch untersucht und es erfolgte eine Blutuntersuchung mit Analyse hämatologischer und klinisch-chemischer Parameter sowie der Konzentration des natriuretischen Peptids Typ B (NT-proBNP). Ergebnisse Zum MZP2 zeigten die Hunde, wie bereits zum MZP1, nach Belastung ein steifes Gangbild, Muskelschwäche und -schmerz und hatten einen dunkelbraun verfärbten Urin. Bei den hämatologischen Parametern und der NT-proBNP-Konzentration ergaben sich, wie zum MZP1, keine Abweichungen vom Referenzbereich. Die Aktivitäten der Kreatinkinase und Alanin-Aminotransferase unterschieden sich statistisch nicht signifikant zwischen beiden MZP (pCK = 0,31, pALT = 0,64). Nach Auswertung einer Besitzerbefragung und der klinisch-neurologischen Untersuchung der Hunde ließ sich im Rahmen der Verlaufsuntersuchung keine Verbesserung der myopathischen Beschwerden feststellen. Schlussfolgerung und klinische Relevanz Die orale Supplementierung von L-Carnitin und Koenzym Q10 sowie spezielle diätetische Maßnahmen über 1 Jahr führten zu keiner Verbesserung der klinischen Symptomatik oder der untersuchten Laborparameter. Die Tiere zeigten keine progressive Verschlechterung der Symptomatik im Vergleich zur Erstvorstellung. Die Prognose ist jedoch als vorsichtig zu bezeichnen, da Daten zum Langzeitverlauf über einige Jahre fehlen. Unsere Ergebnisse bilden eine Grundlage für weitere Forschungen zu Lipidspeichermyopathien, insbesondere mit Fokus auf die belastungsabhängige metabolische Myopathie des Deutschen Jagdterriers, deren Therapie und eine entsprechende Zuchthygiene.

Rod and cone photoreceptors are specialized retinal neurons that have a fundamental role in visual perception, capturing light and transducing it into a neuronal signal. Aberrant functioning of rod and/or cone photoreceptors can ultimately lead to progressive degeneration and eventually blindness. In man, many rod and rod-cone degenerative diseases are classified as forms of retinitis pigmentosa (RP). Dogs also have a comparable disease grouping termed progressive retinal atrophy (PRA). These diseases are generally due to single gene defects and follow Mendelian inheritance.We collected 51 DNA samples from Miniature Schnauzers affected by PRA (average age of diagnosis ∼3.9 ±1 years), as well as from 56 clinically normal controls of the same breed (average age ∼6.6 ±2.8 years). Pedigree analysis suggested monogenic autosomal recessive inheritance of PRA. GWAS and homozygosity mapping defined a critical interval in the first 4,796,806 bp of CFA15. Whole genome sequencing of two affected cases, a carrier and a control identified two candidate variants within the critical interval. One was an intronic SNV in , and the other was a complex structural variant consisting of the duplication of exon 5 of the gene along with a conversion and insertion (named ). was confirmed homozygous in a cohort of 22 cases, and 12 more cases were homozygous for the CFA15 haplotype. Additionally, the variant was found homozygous in 6 non-affected dogs of age higher than the average age of onset. The variant was found heterozygous (n = 4) and homozygous wild-type (n = 1) in cases either homozygous for or for the mapped CFA15 haplotype. We detected the wildtype and three aberrant transcripts in isolated white blood cell mRNA extracted from a PRA case homozygous for , and the aberrant transcripts involved inclusion of the duplicated exon 5 and novel exons following the activation of cryptic splice sites. No neurological signs were detected among the dogs homozygous for the variant. Therefore, we propose as causative for a non-syndromic form of PRA (PRA ) that shows incomplete penetrance in Miniature Schnauzers, potentially related to the presence of the wild-type transcript. To our knowledge, this is the first case of isolated retinal degeneration associated with a variant.

White spotting phenotypes in horses may be caused by developmental alterations impairing melanoblast differentiation, survival, migration and/or proliferation. Candidate genes for white-spotting phenotypes in horses include EDNRB, KIT, MITF, PAX3 and TRPM1. We investigated a German Riding Pony with a sabino-like phenotype involving extensive white spots on the body together with large white markings on the head and almost completely white legs. We obtained whole genome sequence data from this horse. The analysis revealed a heterozygous 1273-bp deletion spanning parts of intron 2 and exon 3 of the equine KIT gene (Chr3: 79 579 925-79 581 197). We confirmed the breakpoints of the deletion by PCR and Sanger sequencing. Knowledge of the functional impact of similar KIT variants in horses and other species suggests that this deletion represents a plausible candidate causative variant for the white-spotting phenotype. We propose the designation W28 for the mutant allele.

The Ehlers-Danlos syndromes (EDSs) are a heterogeneous group of inherited connective tissue disorders characterized by skin hyperextensibility, joint hypermobility and tissue fragility. Inherited disorders similar to human EDS have been reported in different mammalian species. In the present study, we investigated a female mixed-breed dog with clinical signs of EDS. Whole-genome sequencing of the affected dog revealed two missense variants in the TNXB gene, encoding the extracellular matrix protein tenascin XB. In humans, TNXB genetic variants cause classical-like EDS or the milder hypermobile EDS. The affected dog was heterozygous at both identified variants. Each variant allele was transmitted from one of the case's parents, consistent with compound heterozygosity. Although one of the variant alleles, XM_003431680.3:c.2012G>A, p.(Ser671Asn), was private to the family of the affected dog and absent from whole-genome sequencing data of 599 control dogs, the second variant allele, XM_003431680.3:c.2900G>A, p.(Gly967Asp), is present at a low frequency in the Chihuahua and Poodle population. Given that TNXB is a functional candidate gene for EDS, we suggest that compound heterozygosity for the identified TNXB variants may have caused the EDS-like phenotype in the affected dog. Chihuahuas and Poodles should be monitored for EDS cases, which might confirm the hypothesized pathogenic effect of the segregating TNXB variant.

Congenital hemidysplasia with ichthyosiform nevus and limb defects syndrome in humans is a genodermatosis characterized by inflammatory linear verrucous epidermal nevi (ILVEN), often showing a striking lateralization pattern. It is caused by variants in the NSDHL gene encoding a 3β-hydroxysteroid dehydrogenase involved in the cholesterol biosynthesis pathway. In the present study, we investigated a female Chihuahua, which showed clinical and histological signs of ILVEN. We performed a candidate gene analysis in the affected animal. This analysis revealed a single missense variant in the NSDHL gene in the affected dog (XM_014111859.2:c.700G>A). The variant is predicted to cause a non-conservative amino acid change from glycine to arginine, XP_013967334.1:p.(Gly234Arg). The mutant allele was absent from WGS data of 594 genetically diverse dogs and eight wolves. Sanger sequencing confirmed that the variant was heterozygous in the affected dog and absent from 22 control Chihuahuas. Based on the knowledge about the functional impact of NSDHL variants in dogs and other species, c.700G>A is probably pathogenic and a convincing candidate causative variant for the observed skin lesions in the affected Chihuahua.

Two clinical forms of ichthyosis in cattle have been reported, ichthyosis fetalis and congenital ichthyosis. Ichthyosis poses animal welfare and economic issues and the more severe form, ichthyosis fetalis, is lethal. A Shorthorn calf with ichthyosis fetalis was investigated and a likely causal missense variant on chromosome 2 in the ABCA12 gene (NM_001191294.2:c.6776T>C) was identified by whole genome sequencing. Mutations in the ABCA12 gene are known to cause ichthyosis fetalis in cattle and Harlequin ichthyosis in humans. Sanger sequencing of the affected calf and the dam confirmed the variant was homozygous in the affected calf and heterozygous in the dam. Further genotyping of 130 Shorthorn animals from the same property revealed an estimated allele frequency of 3.8%. The presented findings enable genetic testing for breeding and diagnostics.

A specific white spotting phenotype, termed finching or line-backed spotting, is known for all Pinzgauer cattle and occurs occasionally in Tux-Zillertaler cattle, two Austrian breeds. The so-called Pinzgauer spotting is inherited as an autosomal incompletely dominant trait. A genome-wide association study using 27 white spotted and 16 solid-coloured Tux-Zillertaler cattle, based on 777k SNP data, revealed a strong signal on chromosome 6 at the KIT locus. Haplotype analyses defined a critical interval of 122 kb downstream of the KIT coding region. Whole-genome sequencing of a Pinzgauer cattle and comparison to 338 control genomes revealed a complex structural variant consisting of a 9.4-kb deletion and an inversely inserted duplication of 1.5 kb fused to a 310-kb duplicated segment from chromosome 4. A diagnostic PCR was developed for straightforward genotyping of carriers for this structural variant (KIT ) and confirmed that the variant allele was present in all Pinzgauer and most of the white spotted Tux-Zillertaler cattle. In addition, we detected the variant in all Slovenian Cika, British Gloucester and Spanish Berrenda en negro cattle with similar spotting patterns. Interestingly, the KIT variant occurs in some white spotted animals of the Swiss breeds Evolèner and Eringer. The introgression of the KIT variant confirms admixture and the reported historical relationship of these short-headed breeds with Austrian Tux-Zillertaler and suggests a mutation event, occurring before breed formation.

Major characteristics of coat variation in dogs can be explained by variants in only a few genes. Until now, only one missense variant in the KRT71 gene, p.Arg151Trp, has been reported to cause curly hair in dogs. However, this variant does not explain the curly coat in all breeds as the mutant 151Trp allele, for example, is absent in Curly Coated Retrievers. We sequenced the genome of a Curly Coated Retriever at 22× coverage and searched for variants in the KRT71 gene. Only one protein‐changing variant was present in a homozygous state in the Curly Coated Retriever and absent or present in a heterozygous state in 221 control dogs from different dog breeds. This variant, NM_001197029.1:c.1266_1273delinsACA, was an indel variant in exon 7 that caused a frameshift and an altered and probably extended C‐terminus of the KRT71 protein NP_001183958.1:p.(Ser422ArgfsTer?). Using Sanger sequencing, we found that the variant was fixed in a cohort of 125 Curly Coated Retrievers and segregating in five of 14 additionally tested breeds with a curly or wavy coat. KRT71 variants cause curly hair in humans, mice, rats, cats and dogs. Specific KRT71 variants were further shown to cause alopecia. Based on this knowledge from other species and the predicted molecular consequence of the newly identified canine KRT71 variant, it is a compelling candidate causing a second curly hair allele in dogs. It might cause a slightly different coat phenotype than the previously published p.Arg151Trp variant and could potentially be associated with follicular dysplasia in dogs.