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)

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

TBL1XR1 is a member of the WD40 repeat-containing gene family. Mutations of TBL1XR1 have been reported in neurodevelopmental disorders (NDDs). Although the phenotypes of some patients have been described in single studies, few studies have reviewed the genotype and phenotype relationships using a relatively large cohort of patients with TBL1XR1 mutations. Herein, we report a new de novo frameshift mutation in TBL1XR1 (NM_024665.4, c.388_389delAC, p.T130Sfs*14) in a patient with autism spectrum disorder (ASD). To explore the correlations between genotypes and phenotypes for TBL1XR1 in NDDs, we manually curated and analyzed 38 variants and the associated phenotypes from 50 individuals with NDDs. TBL1XR1 mutations lead to a wide range of phenotypic defects. We conclude that the most common phenotypes associated with TBL1XR1 mutations were language and motor developmental delay, intellectual disabilities, facial deformity, hypotonia, and microcephaly. Our study provides a comprehensive spectrum of neurodevelopmental phenotypes caused by TBL1XR1 mutations, which is important for genetic diagnosis and precision clinical management.
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PMID:Genotype and Phenotype Correlations for TBL1XR1 in Neurodevelopmental Disorders. 3252 19