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Biallelic pathogenic variants in LAMB1 have been associated with autosomal recessive lissencephaly 5 (OMIM 615191), which is characterized by brain malformations (cobblestone lissencephaly, hydrocephalus), developmental delay, and epilepsy. Pathogenic variants in LAMB1 are rare, with only 11 pathogenic variants and 11 patients reported to date. Here, we report on a 6‐year‐old patient from a consanguineous family with profound developmental delay, microcephaly, and a history of a perinatal cerebrovascular event. Brain magnetic resonance imaging (MRI) showed cerebellar cystic defects, signal intensity abnormalities, and a hypoplastic corpus callosum. Trio‐exome analysis revealed a homozygous in‐frame deletion of Exons 23 and 24 of LAMB1 affecting 104 amino acids including the epidermal growth factor (EGF)‐like units 11 and 12 in Domain III. To our knowledge, this is the first reported in‐frame deletion in LAMB1. Our findings broaden the clinical and molecular spectrum of LAMB1‐associated syndromes. [ABSTRACT FROM AUTHOR]

Background: Variants in genes of the nucleotide excision repair (NER) pathway have been associated with heterogeneous clinical presentations ranging from xeroderma pigmentosum to Cockayne syndrome and trichothiodystrophy. NER deficiencies manifest with photosensitivity and skin cancer, but also developmental delay and early‐onset neurological degeneration. Adult‐onset neurological features have been reported in only a few xeroderma pigmentosum cases, all showing at least mild skin manifestations. Objective: The aim of this multicenter study was to investigate the frequency and clinical features of patients with biallelic variants in NER genes who are predominantly presenting with neurological signs. Methods: In‐house exome and genome datasets of 14,303 patients, including 3543 neurological cases, were screened for deleterious variants in NER‐related genes. Clinical workup included in‐depth neurological and dermatological assessments. Results: We identified 13 patients with variants in ERCC4 (n = 8), ERCC2 (n = 4), or XPA (n = 1), mostly proven biallelic, including five different recurrent and six novel variants. All individuals had adult‐onset progressive neurological deterioration with ataxia, dementia, and frequently chorea, neuropathy, and spasticity. Brain magnetic resonance imaging showed profound global brain atrophy in all patients. Dermatological examination did not show any skin cancer or pronounced ultraviolet damage. Conclusions: We introduce NERDND as adult‐onset neurodegeneration (ND) within the spectrum of autosomal recessive NER disorders (NERD). Our study demonstrates that NERDND is probably an underdiagnosed cause of neurodegeneration in adulthood and should be considered in patients with overlapping cognitive and movement abnormalities. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Aymé‐Gripp syndrome (AYGRPS) is a recognizable condition caused by a restricted spectrum of dominantly acting missense mutations affecting the transcription factor MAF. Major clinical features of AYGRPS include congenital cataracts, sensorineural hearing loss, intellectual disability, and a distinctive flat facial appearance. Skeletal abnormalities have also been observed in affected individuals, even though these features have not been assessed systematically. Expanding the series with four additional patients, here we provide a more accurate delineation of the molecular aspects and clinical phenotype, particularly focusing on the skeletal features characterizing this disorder. Apart from previously reported malar flattening and joint limitations, we document that carpal/tarsal and long bone defects, and hip dysplasia occur in affected subjects more frequently than formerly appreciated. [ABSTRACT FROM AUTHOR]

A recurrent de novo missense variant in KCNC1, encoding a voltage‐gated potassium channel expressed in inhibitory neurons, causes progressive myoclonus epilepsy and ataxia, and a nonsense variant is associated with intellectual disability. We identified three new de novo missense variants in KCNC1 in five unrelated individuals causing different phenotypes featuring either isolated nonprogressive myoclonus (p.Cys208Tyr), intellectual disability (p.Thr399Met), or epilepsy with myoclonic, absence and generalized tonic‐clonic seizures, ataxia, and developmental delay (p.Ala421Val, three patients). Functional analyses demonstrated no measurable currents for all identified variants and dominant‐negative effects for p.Thr399Met and p.Ala421Val predicting neuronal disinhibition as the underlying disease mechanism. [ABSTRACT FROM AUTHOR]

Autosomal recessive keratoderma‐ichthyosis‐deafness (ARKID) syndrome is a rare multisystem disorder caused by biallelic mutations in VPS33B; only three patients have been reported to date. ARKID syndrome is allelic to arthrogryposis‐renal dysfunction‐cholestasis (ARC) syndrome (MIM #208085), a severe disorder with early lethality whose phenotypic characteristics also include ichthyosis, hearing loss, severe failure to thrive, platelet dysfunction and osteopenia. We report on an 11‐year‐old male patient with ARKID syndrome and compound heterozygous VPS33B mutations, one of which [c.1440delG; p.(Arg481Glyfs*11)] was novel. Clinical features of this patient included ichthyosis, palmoplantar keratosis, hearing loss, intellectual disability, unilateral hip dislocation, microcephaly and short stature. He also had copper hepatopathy and exocrine pancreatic insufficiency, features that have so far been associated with neither ARKID nor ARC syndrome. The patient broadens the clinical and molecular spectrum of ARKID syndrome and contributes to genotype–phenotype associations of this rare disorder. [ABSTRACT FROM AUTHOR]

MED12 is a member of the large Mediator complex that controls cell growth, development, and differentiation. Mutations in MED12 disrupt neuronal gene expression and lead to at least three distinct X‐linked intellectual disability syndromes (FG, Lujan‐Fryns, and Ohdo). Here, we describe six families with missense variants in MED12 (p.(Arg815Gln), p.(Val954Gly), p.(Glu1091Lys), p.(Arg1295Cys), p.(Pro1371Ser), and p.(Arg1148His), the latter being first reported in affected females) associated with a continuum of symptoms rather than distinct syndromes. The variants expanded the genetic architecture and phenotypic spectrum of MED12‐related disorders. New clinical symptoms included brachycephaly, anteverted nares, bulbous nasal tip, prognathism, deep set eyes, and single palmar crease. We showed that MED12 variants, initially implicated in X‐linked recessive disorders in males, may predict a potential risk for phenotypic expression in females, with no correlation of the X chromosome inactivation pattern in blood cells. Molecular modeling (Yasara Structure) performed to model the functional effects of the variants strongly supported the pathogenic character of the variants examined. We showed that molecular modeling is a useful method for in silico testing of the potential functional effects of MED12 variants and thus can be a valuable addition to the interpretation of the clinical and genetic findings. [ABSTRACT FROM AUTHOR]

Phosphoribosylpyrophosphate synthetase (PRPPS) superactivity (OMIM 300661) is a rare inborn error of purine metabolism that is caused by gain-of-function mutations in the X-chromosomal gene PRPS1 (Xq22.3). Clinical characteristics include congenital hyperuricemia and hyperuricosuria, gouty arthritis, urolithiasis, developmental delay, hypotonia, recurrent infections, short stature, and hearing loss. Only eight families with PRPPS superactivity and PRPS1 gain-of-function mutations have been reported to date. We report on a 7-year-old boy with congenital hyperuricemia, urolithiasis, developmental delay, short stature, hypospadias, and facial dysmorphisms. His mother also suffered from hyperuricemia that was diagnosed at age 13 years. A novel PRPS1 missense mutation (c.573G>C, p.[Leu191Phe]) was detected in the proband and his mother. Enzyme activity analysis confirmed superactivity of PRPP synthetase. Analysis of the crystal structure of human PRPPS suggests that the Leu191Phe mutation affects the architecture of both allosteric sites, thereby preventing the allosteric inhibition of the enzyme. The family reported here broadens the clinical spectrum of PRPPS superactivity and indicates that this rare metabolic disorder might be associated with a recognizable facial gestalt. [ABSTRACT FROM AUTHOR]

Objective To define the molecular basis of a multisystem phenotype with progressive musculoskeletal disease of the hands and feet, including camptodactyly, subluxation, and tendon rupture, reminiscent of Jaccoud's arthropathy. Methods We identified 2 families segregating an autosomal-dominant phenotype encompassing musculoskeletal disease and variable additional features, including psoriasis, dental abnormalities, cardiac valve involvement, glaucoma, and basal ganglia calcification. We measured the expression of interferon (IFN)-stimulated genes in the peripheral blood and skin, and undertook targeted Sanger sequencing of the IFIH1 gene encoding the cytosolic double-stranded RNA (dsRNA) sensor melanoma differentiation-associated protein 5 (MDA-5). We also assessed the functional consequences of IFIH1 gene variants using an in vitro IFNβ reporter assay in HEK 293T cells. Results We recorded an up-regulation of type I IFN-induced gene transcripts in all 5 patients tested and identified a heterozygous gain-of-function mutation in IFIH1 in each family, resulting in different substitutions of the threonine residue at position 331 of MDA-5. Both of these variants were associated with increased IFNβ expression in the absence of exogenous dsRNA ligand, consistent with constitutive activation of MDA-5. Conclusion These cases highlight the significant musculoskeletal involvement that can be associated with mutations in MDA-5, and emphasize the value of testing for up-regulation of IFN signaling as a marker of the underlying molecular lesion. Our data indicate that both Singleton-Merten syndrome and neuroinflammation described in the context of MDA-5 gain-of-function constitute part of the same type I interferonopathy disease spectrum, and provide possible novel insight into the pathology of Jaccoud's arthropathy. [ABSTRACT FROM AUTHOR]

Mutations in DLG3 are a rare cause of non-syndromic X-linked intellectual disability (XLID) (MRX90, OMIM *300189). Only ten DLG3 mutations have been reported to date. The majority of female heterozygous mutation carriers was healthy and had random X-inactivation patterns. We report on an XLID family with a novel DLG3 mutation. The 12-year-old male index patient had moderate intellectual disability (ID) and dysmorphic features. The mutation was also present in four female relatives. A maternal aunt had moderate ID and significantly skewed X-inactivation favorably inactivating the normal DLG3 allele. The proband's healthy mother also had skewed X-inactivation but in the opposite direction (i.e., inactivation of the mutated allele). Two other female relatives had intermediate cognitive phenotypes and random X-inactivation. This family broadens the mutational and phenotypical spectrum of DLG3-associated XLID and demonstrates that heterozygous female mutation carriers can be as severely affected as males. Reports of additional families will be needed to elucidate the causes of unfavorable skewing in female XLID patients. [ABSTRACT FROM AUTHOR]

Interstitial deletions including chromosome region 1q23.3q24.1 are rare. Only eight patients with molecularly characterized deletions have been reported to date. Their phenotype included intellectual disability/developmental delay, growth retardation, microcephaly, congenital heart disease, and renal malformations. We report on a female patient with mild developmental delay, congenital heart disease, and bilateral renal hypoplasia in whom an interstitial de novo deletion of approximately 2.7 Mb in 1q23.3q24.1 was detected by array CGH. This is the smallest deletion described in this region so far. Genotype-phenotype comparison with previously published patients allowed us to propose LMX1A and RXRG as potential candidate genes for intellectual disability, PBX1 as a probable candidate gene for renal malformation, and enabled us to narrow down a chromosome region associated with microcephaly. © 2016 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The clinical diagnosis of Lujan-Fryns syndrome (LFS) comprises X-linked intellectual disability (XLID) with marfanoid habitus, distinct combination of minor facial anomalies and nasal speech. However the definition of syndrome was significantly broadened since the original report and implies ID with marfanoid habitus. Mutations of three genes (MED12, UPF3B, and ZDHHC9) have been reported in "broadly defined" LFS. We examined these genes in 28 individuals with a tentative clinical diagnosis of LFS but we did not identify any causative mutation. By molecular karyotyping we detected other disorders, i.e., Phelan-McDermid syndrome and 16p11.2 microduplication, each in one patient. One affected individual was carrier of a different recurrent duplication on 16p11.2 that has been reported several times to the DECIPHER and ISCA databases in individuals with autism, intellectual disability (ID), and developmental delay. It may represent a new duplication syndrome. We also identified previously unreported de novo duplication on chromosome 12p13.31 which we considered to be disease-causing. X-exome sequencing of four individuals revealed private or non-recurrent mutations in NKAP and LAS1L in one patient each. While LFS is defined as a form of XLID, there seem to be various conditions that have rather similar phenotypes. Therefore, the combination of ID and marfanoid habitus in a male patient is not sufficient for the diagnosis of LFS.Wesuggest that the diagnosis of LFS in patients with ID and marfanoid habitus should be made only in presence of specific facial features, nasal speech and obvious X-linked segregation of the disorder or an unambiguously pathogenic mutation in the MED12. [ABSTRACT FROM AUTHOR]

Interstitial deletions encompassing chromosome bands 1p32.1p32.3 are rare. Only nine unrelated patients with partially overlapping 1p32.1p32.3 deletions of variable size and position have been reported to date. We report on a 17-month-old boy with choanal atresia, hearing loss, urogenital anomalies, and microcephaly in whom an interstitial de novo deletion of 6.4 Mb was detected in 1p32.1p32.3 (genomic position chr1:54,668,618-61,113,264 according to GRCh37/hg19). The deleted region harbors 31 RefSeq genes. Notable genes in the region are PCSK9, haploinsufficiency of which caused low LDL cholesterol plasma levels in the patient, and DAB1, which is a candidate gene for cognitive deficits, microcephaly, and cerebral abnormalities such as ventriculomegaly and agenesis of the corpus callosum. Choanal atresia, microcephaly, and severe hearing loss were previously not known to be associated with 1p32 deletions. Our reported patient thus broadens the spectrum of clinical findings in this chromosome region and further facilitates genotype-phenotype correlations. Additional patients with overlapping deletions and/or point mutations in genes of this region need to be identified to elucidate the role of individual genes for the complex clinical manifestations. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Isolated interstitial duplications of chromosome band 1q25 are apparently very rare; no patients with detailed molecular and clinical characterization of duplications restricted to this region have been published to date. We report on a 9-year-old girl with mild cognitive deficits, tall stature, macrocephaly and discrete dysmorphic features in whom a de novo interstitial 7.5 Mb duplication of 1q25.1q25.3 was detected by SNP array analysis (arr[hg19] 1q25.1q25.3(173,925,505-181,381,242)x3 dn). The duplicated region was inversely inserted into chromosome band 1q42.2: 46,XX,der(1)(pter→q42.2::q25.3→q25.1::q42.2→qter). Overexpression of one or several of the 87 genes in the duplicated interval was presumably the major causative factor for the clinical manifestations. Reports of additional patients with overlapping duplications will be needed to establish detailed karyotype-phenotype correlations and to gain a better understanding of the underlying pathomechanisms. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Interstitial deletions of chromosome band 14q24.1q24.3 are apparently very rare. We report on three unrelated patients with overlapping de novo deletions of sizes 5.4, 2.8, and 2.3 Mb in this region. While some clinical problems such as intestinal malrotation, cryptorchidism, and ectopic kidney were only observed in single patients, all three patients had mild intellectual disability, congenital heart defects (truncus arteriosus, pulmonary atresia, atrial septal defect, and/or ventricular septal defect), brachydactyly, hypertelorism, broad nasal bridge, and thin upper lips. Likely haploinsufficiency of one or several of the 19 genes in the common deleted interval ( ACTN1, DCAF5, EXD2, GALNTL1, ERH, SLC39A9, PLEKHD1, CCDC177, KIAA0247, LOC100289511, SRSF5, SLC10A1, SMOC1, SLC8A3, ADAM21P1, COX16, SYNJ2BP, SYNJ2BP-COX16, ADAM21) was responsible for these manifestations, but apart from SMOC1, mutations in which cause autosomal recessive Waardenburg anophthalmia syndrome, and ACTN1, mutations in which are associated with congenital macrothrombocytopenia, no disease associations have so far been reported for the other genes. Functional studies and a systematic search for mutations or chromosome aberrations in this region will elucidate the role of individual genes in the clinical manifestations and will provide insight into the underlying biological mechanisms. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

ABSTRACT Introduction: Complex forms of spastic paraplegia (SPG) are rare and genetically heterogeneous. In apparently sporadic cases, analysis of known SPG genes often fails to reveal a mutation. Methods: We report a 24-year-old patient with a syndrome of spastic paraplegia, ataxia, frontotemporal dementia, and lower motor neuron involvement. Results: Screening of the patient's genome for copy number variation identified a novel 276 kb deletion spanning the first exon of the GRID2 gene. MRI scan showed atrophy of the cerebellum, and electromyography revealed a chronic disorder of motor neurons or their axons. A deletion in GRID2, coding for the glutamate receptor delta-2 subunit precursor protein, was excluded in either parent, suggesting that the deletion in the index patient occurred de novo. Conclusions: We hypothesize that the deletion identified here is the cause of our patient's clinical presentation, due to the resemblance to the GRID2 mutation phenotype in mouse models. Muscle Nerve 49: 289-292, 2014 [ABSTRACT FROM AUTHOR]

Succinic semialdehyde dehydrogenase (SSADH) deficiency is a disorder of the catabolism of the neurotransmitter gamma-aminobutyric acid (GABA) with a very variable clinical phenotype ranging from mild intellectual disability to severe neurological defects. We report here on a large Iranian family with four affected patients presenting with severe intellectual disability, developmental delay and generalized tonic-clonic seizures. Molecular genetic analysis revealed a missense mutation c.901A>G (p.K301E, RefSeq number NM_001080) in ALDH5A1 co-segregating with the disease in the family. The missense mutation affects an amino acid residue that is highly conserved across the animal kingdom. Protein modeling showed that p.K301E most likely leads to a loss of NAD+ binding and a predicted decrease in the free energy by 6.67 kcal/mol furthermore suggests a severe destabilization of the protein. In line with these in silico observations, no SSADH enzyme activity could be detected in patient lymphoblasts. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Deletions of chromosome band 12q24.33 are rare. We report on a 17-year-old male patient with intellectual disability but no major malformations or dysmorphic features in whom a de novo interstitial 660 kb deletion in 12q24.33 was detected by SNP array analysis. This deletion was secondary to a translocation t(12;14)(q24.3;q13)dn that also led to a small deletion in 14q21.1 and a small duplication in 2p23.1. The deletion overlaps with two previously published larger deletions in patients who suffered from intellectual disability, obesity, and polycystic kidney disease, indicating that haploinsufficiency of one or several of the genes in the deleted interval of the patient reported here causes intellectual deficits, but not obesity or renal problems. The 14 RefSeq genes that are harbored by this deletion include P2RX2, which had previously been proposed as a candidate gene for intellectual disability. Thus, the patient reported here broadens our knowledge of the phenotypic consequences of deletions in 12q24.33 and facilitates genotype-phenotype correlations for chromosome aberrations of this region. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Genetic factors represent an important etiologic group in the causation of intellectual disability. We describe a Saudi Arabian family with closley related parents in which four of six children were affected by a congenital cognitive disturbance. The four individuals (aged 18, 16, 13, and 2 years when last examined) had motor and cognitive delay with seizures in early childhood, and three of the four (sparing only the youngest child) had progressive, severe cognitive decline with spasticity. Two affected children had ocular malformations, and the three older children had progressive visual loss. The youngest had normal globes with good functional vision when last examined but exhibited the oculodigital sign, which may signify a subclinical visual deficit. A potentially deleterious nucleotide change (c.1A>G; p.Met1Val) in the C12orf57 gene was homozygous in all affected individuals, heterozygous in the parents, and absent in an unaffected sibling and >350 normal individuals. This gene has no known function. This family manifests a autosomal recessive syndrome with some phenotypic variability that includes abnormal development of brain and eyes, delayed cognitive and motor milestones, seizures, and a severe cognitive and visual decline that is associated with a homozygous variant in a newly identified gene. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Mutations or deletions of ACSL4 ( FACL4, OMIM 300157) are a rare cause of non-syndromic X-linked intellectual disability. We report on a 10-year-old male patient with moderate intellectual disability, sensorineural hearing loss, facial dysmorphism, pyloric stenosis, and intestinal obstruction in whom a de novo Xq22.3-q23 deletion was detected by SNP array analysis. The deleted 1.56 Mb interval harbored ACSL4 and eight neighboring genes ( GUCY2F, NXT2, KCNE1L, TMEM164, MIR3978, AMMECR1, SNORD96B, and RGAG1). In contrast to previously reported patients with chromosome aberrations in the region of the AMME complex (Alport syndrome, intellectual disability, midface hypoplasia, and elliptocytosis, OMIM 300194), this deletion did not contain the Alport syndrome gene COL4A5, suggesting that loss of one or several of the other genes in this interval is responsible for the clinical problems. In summary, the patient reported here broadens our knowledge of the phenotypic consequences of deletions of chromosome region Xq22.3-q23 and provides further proof for ACSL4 as an X-linked intellectual disability gene. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The article discusses the mutations in patients with cranioectodermal dysplasia (CED). It states that CED is a rare autosomal recessive ciliopathy characterized by craniosynostosis, dolichocephaly, narrow chest, sparse hair, epicanthal folds, microdontia, brachyda. It mentions that patients with WDR35 mutations need to be identified to get more insight into the clinical variability of WDR35-associated CED and to establish comprehensive genotype-phenotype correlations.

Interstitial deletions of the short arm of chromosome 3 are rare. We report on a 3-year-old girl with intellectual disability, muscular hypotonia, strabismus, and facial anomalies in whom an interstitial 1.24 Mb deletion in 3p25.3-p26.1 was detected by SNP array analysis. The deleted region harbors 11 RefSeq genes including CAV3 and SRGAP3/MEGAP, which had been associated with muscle disorders and intellectual disability, respectively. The deletion overlaps with a slightly larger deletion in a girl with a more complex phenotype including congenital heart defect and epilepsy, which indicates that haploinsufficiency of one or several of the genes in the deleted interval causes intellectual deficits, but not heart defects or epilepsy. Thus, the patient broadens our knowledge of the phenotypic consequences of deletions in 3p25.3-p26.1 and facilitates genotype-phenotype correlations for chromosome aberrations of this region. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Interstitial deletions of chromosome bands 9q34.11-q34.13 are rare. We report on a 16-year-old female patient with severe intellectual disability, congenital hydrocephalus, cleft lip and palate, talipes equinovarus, epilepsy, kyphoscoliosis, convergent strabismus, severe short stature, dystrophy, and facial dysmorphic signs. Array analysis revealed a 3.7 Mb interstitial deletion in 9q34.11-q34.13. The deletion harbors more than 60 genes, including SPTAN1, DYT1/TOR1A, ABL1, ASS1, LAMC3, POMT1, DOLK, and GLE1, mutations in which have previously been associated with monogenic disorders. This is the first patient with a deletion of this size and position in 9q34.11-q34.13. Reports of additional patients with aberrations in this region will be needed to establish karyotype-phenotype correlations and to gain information on the contribution of individual genes for the clinical manifestations. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

X-linked intellectual disability (XLID) is a heterogeneous disorder, and mutations in more than 90 genes have been associated with XLID to date. We report on a large multi-generational German family in which the affected male family members had nonsyndromic intellectual disability, that is, they had neither abnormal body measurements nor any other significant clinical problems. Molecular genetic analysis revealed a frameshift mutation in GDI1 (c.1185_1186delAG; Ser396ProfsX15) that co-segregated with the disease. GDI1 encodes for the GDP-dissociation inhibitor alpha (αGDI), a protein involved in the regulation of the activity of Rab GTPases. Only three families with GDI1 mutations have been reported so far. The present family supports the lack of additional phenotypic features in patients with GDI1 mutations, rendering a clinical diagnosis of GDI1-associated XLID impossible. Thus, this family not only broadens the spectrum of GDI1 mutations but also emphasizes the need for parallel testing of all known genes associated with ID in patients with an unspecific phenotype. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Interstitial deletions of chromosome band Xq26.3 are rare. We report on a 2-year-old boy in whom array comparative genomic hybridization analysis revealed an interstitial 314 kb deletion in Xq26.3 affecting SLC9A6 and FHL1. Mutations in SLC9A6 are associated with Christianson syndrome (OMIM 300243), a syndromic form of X-linked mental retardation (XLMR) characterized by microcephaly, severe global developmental delay, ataxia and seizures. FHL1 mutations cause Emery-Dreifuss muscular dystrophy (OMIM 310300), X-linked myopathy with postural muscle atrophy (XMPMA, OMIM 300696), scapuloperoneal myopathy (OMIM 300695), or reducing body myopathy (OMIM 300717, 300718). The clinical problems of the patient reported here comprised severe intellectual disability, absent speech, ataxia, epilepsy, and gastroesophageal reflux, and could mostly be attributed to SLC9A6 insufficiency. In contrast to the majority of reported Christianson syndrome patients who were microcephalic, this patient was normocephalic, but his head circumference had decelerated from the 50th centile at birth to the 25th centile at the age of $2{\raise0.5ex\hbox{$\scriptstyle 2$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle {12}$}}$ years. Muscle problems due to the FHL1 deletion are not to be expected before late childhood, which is the earliest age of onset for FHL1 associated Emery-Dreifuss muscular dystrophy. This patient broadens the spectrum of SLC9A6 mutations and contributes to the clinical delineation of Christianson syndrome. This is also the first patient with a deletion affecting both SLC9A6 and the complete FHL1 gene. © 2011 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The genetic basis of autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to suspect that the number of underlying gene defects may well go beyond 1,000. To date, however, only less than 10 genes have been implicated in non-specific/non-syndromic ARMR (NS-ARMR). As part of an ongoing systematic study aiming to identify further ARMR genes, we investigated a consanguineous family with three patients with NS-ARMR. By linkage analysis and subsequent mutation screening we identified a novel nonsense mutation (c.163C > T [p.Q55X]) in the second exon of the TUSC3 gene. This is the third MR causing defect in TUSC3 to be described and the second independent mutation in this gene in a cohort of more than 200 ARMR families from the Iranian population. This argues for a more prominent role of TUSC3 in the etiology of this genetically heterogeneous disorder as compared to most of the other so far identified ARMR genes. © 2011 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]

Budny B, Badura-Stronka M, Materna-Kiryluk A, Tzschach A, Raynaud M, Latos-Bielenska A, Ropers HH. Novel missense mutations in the ubiquitination-related gene UBE2A cause a recognizable X-linked mental retardation syndrome. Recently, a truncating mutation of the UBE2A gene has been observed in a family with X-linked mental retardation (XLMR) (1) . The three affected males had similar phenotypes, including seizures, obesity, marked hirsutism and a characteristic facial appearance. Here, we report on two families with a total of seven patients and a clinically very similar syndromic form of XLMR. Linkage analysis was performed in the larger of these families, and screening several positional candidate genes revealed a G23R missense mutation in the UBE2A gene. Subsequent UBE2A screening of a phenotypically similar second family revealed another missense mutation, R11Q, again affecting an evolutionarily conserved amino acid close to the N-terminus of the protein. SIFT and PolyPhen analyses suggest that both mutations are pathogenic, which is supported by their absence in 168 healthy controls. Thus, both missense and truncating mutations can give rise to a specific, syndromic form of XLMR which is identifiable in a clinical setting. [ABSTRACT FROM AUTHOR]

We report on a 30-year-old man with azoospermia, primary hypogonadism and minor dysmorphic features who carried a balanced insertional chromosome translocation inv ins (2p24;4q28.3q31.22) de novo. Molecular cytogenetic analyses of the chromosome breakpoints revealed the localization of the breakpoint in 4q28.3 between BACs RP11-143E9 and RP11-285A15, an interval that harbours the PCDH10 gene. In 4q31.22, a breakpoint-spanning clone (RP11-6L6) was identified which contains the genes LSM6 and SLC10A7. On chromosome 2, BACs RP11-531P14 and RP11-360O18 flank the breakpoint in 2p24, a region void of known genes. In conclusion, the chromosome aberration of this patient suggests a gene locus for primary hypogonadism in 2p24, 4q28.3 or 4q31.2, and three possible candidate genes ( LSM6, SLC10A7 and PCDH10) were identified by breakpoint analyses. [ABSTRACT FROM AUTHOR]

A letter to the editor about the molecular characterization of a balanced chromosome translocation in psoriasis vulgaris is presented.