Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026827 (hypotonia)
 5,860 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently WAC was reported as a candidate gene for intellectual disability (ID) based on the identification of a de novo mutation in an individual with severe ID. WAC regulates transcription-coupled histone H2B ubiquitination and has previously been implicated in the 10p12p11 contiguous gene deletion syndrome. In this study, we report on 10 individuals with de novo WAC mutations which we identified through routine (diagnostic) exome sequencing and targeted resequencing of WAC in 2326 individuals with unexplained ID. All but one mutation was expected to lead to a loss-of-function of WAC. Clinical evaluation of all individuals revealed phenotypic overlap for mild ID, hypotonia, behavioral problems and distinctive facial dysmorphisms, including a square-shaped face, deep set eyes, long palpebral fissures, and a broad mouth and chin. These clinical features were also previously reported in individuals with 10p12p11 microdeletion syndrome. To investigate the role of WAC in ID, we studied the importance of the Drosophila WAC orthologue (CG8949) in habituation, a non-associative learning paradigm. Neuronal knockdown of Drosophila CG8949 resulted in impaired learning, suggesting that WAC is required in neurons for normal cognitive performance. In conclusion, we defined a clinically recognizable ID syndrome, caused by de novo loss-of-function mutations in WAC. Independent functional evidence in Drosophila further supported the role of WAC in ID. On the basis of our data WAC can be added to the list of ID genes with a role in transcription regulation through histone modification.
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PMID:De novo loss-of-function mutations in WAC cause a recognizable intellectual disability syndrome and learning deficits in Drosophila. 2675 81

We present a 7-year old male with severe delays, hypotonia and dysmorphic features who had striking, deep palmar and plantar creases and pillowing of the soft tissues of the palms and soles. His facial features included a high anterior hairline, small eyes with narrowed palpebral fissures, a bulbous nasal tip with a short columella, and a large mouth with a thin upper vermilion, and small chin. He had a submucous cleft palate, bilateral cryptorchidism and hydronephrosis. Cranial imaging demonstrated an Arnold Chiari malformation that was also present in his maternal uncle by report. Exome sequencing revealed a de novo heterozygous sequence variant, p.Tyr446Cys, in TBL1XR1 that has previously been reported in six patients with Pierpont syndrome. This sequence variant occurs in the carboxy-terminal, WD40 domain of the protein. As TBL1XR1 is a critical component of the NCoR/SMRT co-repressor complex and the WD40 repeats are hypothesized to interact with histone H2B and H4, the mutation may impact protein interactions necessary for stabilizing the complex with chromatin. De novo missense and frameshift mutations and deletions involving TBL1XR1 have been described in patients with intellectual disability and autism, but without any of the dysmorphic findings or malformations associated with Pierpont syndrome, implying a mutation-specific mechanism for the pathogenicity of p.Tyr446Cys. Our case is the first individual with this mutation to have a submucous cleft palate and hydronephrosis, although his severe delays, hypotonia, dysmorphic findings and emerging scoliosis appear consistent with previous reports. His distinctive facial and digital features are further evidence that p.Tyr446Cys results in a clinically recognizable, syndromic form of intellectual disability in contrast to other TBL1XR1 mutations.
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PMID:Pierpont syndrome associated with the p.Tyr446Cys missense mutation in TBL1XR1. 2868 24