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Neuronal ceroid lipofuscinosis (NCL) is a group of neurodegenerative disorders that occur in humans, dogs, and several other species. NCL is characterised clinically by progressive deterioration of cognitive and motor function, epileptic seizures, and visual impairment. Most forms present early in life and eventually lead to premature death. Typical pathological changes include neuronal accumulation of autofluorescent, periodic acid‐Schiff‐ and Sudan black B‐positive lipopigments, as well as marked loss of neurons in the central nervous system. Here, we describe a 19‐month‐old Schapendoes dog, where clinical signs were indicative of lysosomal storage disease, which was corroborated by pathological findings consistent with NCL. Whole genome sequencing of the affected dog and both parents, followed by variant calling and visual inspection of known NCL genes, identified a missense variant in CLN6 (c.386T>C). The variant is located in a highly conserved region of the gene and predicted to be harmful, which supports a causal relationship. The identification of this novel CLN6 variant enables pre‐breeding DNA‐testing to prevent future cases of NCL6 in the Schapendoes breed, and presents a potential natural model for NCL6 in humans. [ABSTRACT FROM AUTHOR]

A method to measure genomic response to natural and artificial selection by means of genetic markers in livestock is proposed. Genomic response through several levels of selection was measured using sequential testing for distorted segregation of alleles among selected and nonselected sons, single-sperm typing, and a test with records for growth performance. Statistical power at a significance level of 0.05 was >0.5 for a marker linked to a QTL with recombination fractions 0, 0.10, and 0.20 for detecting genomic responses for gene effects of 0.6, 0.7, and 1.0 phenotypic standard deviations, respectively. Genomic response to artificial selection in six commercial bull sire families comprising 285 half-sib sons selected for growth performance was measured using 282 genetic markers evenly distributed over the cattle genome. A genome-wide test using selected sons was significant (P < 0.001), indicating that selection induces changes in the genetic makeup of commercial cattle populations. Markers located in chromosomes 6, 10, and 16 identified regions in those chromosomes that are changing due to artificial selection as revealed by the association of records of performance with alleles at specific markers. Either natural selection or genetic drift may cause the observed genomic response for markers in chromosomes 1, 7, and 17.

Deficient homozygosity of a variant maintained in a population suggests that the variant may be embryonic lethal. We examined whole genome sequence data from 675 canids to investigate for variants with missing homozygosity and high predicted impact. Our analysis identified 45 variants, in 32 genes. However, further scrutiny of the sequence reads revealed that all but one of these variants were artifacts of the variant calling process when using CanFam3.1, a widely utilized canine reference genome. We demonstrate that the use of multiple, newer reference genomes could reduce artifacts and lead to more accurate variant identification. [ABSTRACT FROM AUTHOR]

Abstract Background Canine behavioural problems, in particular aggression, are important reasons for euthanasia of otherwise healthy dogs. Aggressive behaviour in dogs also represents an animal welfare problem and a public threat. Elucidating the genetic background of adverse behaviour can provide valuable information to breeding programs and aid the development of drugs aimed at treating undesirable behaviour. With the intentions of identifying gene-specific expression in particular brain parts and comparing brains of aggressive and non-aggressive dogs, we studied amygdala, frontal cortex, hypothalamus and parietal cortex, as these tissues are reported to be involved in emotional reactions, including aggression. Based on quantitative real-time PCR (qRT-PCR) in 20 brains, obtained from 11 dogs euthanised because of aggressive behaviour and nine non-aggressive dogs, we studied expression of nine genes identified in an initial screening by subtraction hybridisation. Results This study describes differential expression of the UBE2V2 and ZNF227 genes in brains of aggressive and non-aggressive dogs. It also reports differential expression for eight of the studied genes across four different brain tissues (amygdala, frontal cortex, hypothalamus, and parietal cortex). Sex differences in transcription levels were detected for five of the nine studied genes. Conclusions The study showed significant differences in gene expression between brain compartments for most of the investigated genes. Increased expression of two genes was associated with the aggression phenotype. Although the UBE2V2 and ZNF227 genes have no known function in regulation of aggressive behaviour, this study contributes to preliminary data of differential gene expression in the canine brain and provides new information to be further explored.

Abstract Background A genetic study was performed to identify candidate genes associated with day blindness in the standard wire haired dachshund. Based on a literature review of diseases in dogs and human with phenotypes similar to day blindness, ten genes were selected and evaluated as potential candidate genes associated with day blindness in the breed. Results Three of the genes, CNGB3, CNGA3 and GNAT2, involved in cone degeneration and seven genes and loci, ABCA4, RDH5, CORD8, CORD9, RPGRIP1, GUCY2D and CRX, reported to be involved in cone-rod dystrophies were studied. Polymorphic markers at each of the candidate loci were studied in a family with 36 informative offspring. The study revealed a high frequency of recombinations between the candidate marker alleles and the disease. Conclusion Since all of the markers were at the exact position of the candidate loci, and several recombinations were detected for each of the loci, all ten genes were excluded as causal for this canine, early onset cone-rod dystrophy. The described markers may, however, be useful to screen other canine resource families segregating eye diseases for association to the ten genes.

Abstract Background Polymorphism in genes of regulating enzymes, transporters and receptors of the neurotransmitters of the central nervous system have been associated with altered behaviour, and single nucleotide polymorphisms (SNPs) represent the most frequent type of genetic variation. The serotonin and dopamine signalling systems have a central influence on different behavioural phenotypes, both of invertebrates and vertebrates, and this study was undertaken in order to explore genetic variation that may be associated with variation in behaviour. Results Single nucleotide polymorphisms in canine genes related to behaviour were identified by individually sequencing eight dogs (Canis familiaris) of different breeds. Eighteen genes from the dopamine and the serotonin systems were screened, revealing 34 SNPs distributed in 14 of the 18 selected genes. A total of 24,895 bp coding sequence was sequenced yielding an average frequency of one SNP per 732 bp (1/732). A total of 11 non-synonymous SNPs (nsSNPs), which may be involved in alteration of protein function, were detected. Of these 11 nsSNPs, six resulted in a substitution of amino acid residue with concomitant change in structural parameters. Conclusion We have identified a number of coding SNPs in behaviour-related genes, several of which change the amino acids of the proteins. Some of the canine SNPs exist in codons that are evolutionary conserved between five compared species, and predictions indicate that they may have a functional effect on the protein. The reported coding SNP frequency of the studied genes falls within the range of SNP frequencies reported earlier in the dog and other mammalian species. Novel SNPs are presented and the results show a significant genetic variation in expressed sequences in this group of genes. The results can contribute to an improved understanding of the genetics of behaviour.

Abstract: Objective: To describe the frequency of the nonhomologous end‐joining factor 1 (NHEJ1) mutation and the compliance between clinical and genetic diagnosis of choroidal hypoplasia (CH) in a group of Norwegian Border Collies. Animals studied: Border collie puppies in the age from 5 to 8 weeks. Material and methods: Puppies included in the study had a complete ophthalmological examination. All findings were recorded, and an ECVO scheme form was issued for each puppy. DNA samples were achieved from buccal swabs. Genetic typing was performed for the 7.8‐kb deletion in the gene encoding NHEJ1. Dogs with none, one, or two copies of the mutated allele were classified as free, carriers, and affected, respectively. Results: 103 Border Collie puppies from 16 litters, 52 females and 51 males, were included in the study. Ages ranged from 5.1 to 8.9 weeks. One puppy had clinical findings consistent with CH and optic nerve coloboma compatible with the diagnosis Collie Eye Anomaly (CEA). Findings on ophthalmological examination of the remaining puppies were within normal limits. On genetic testing, 85 puppies were clear of the mutation in the NHEJ1 gene, 17 puppies were carriers, and one puppy was genetically affected. Conclusions: A good compliance between the clinical diagnosis and the genetic test results was found in all of the puppies examined. The allele frequency of the mutation was 6.3%. [ABSTRACT FROM AUTHOR]