Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mild type of autosomal recessive, non-syndromic mental retardation (NSMR) is linked to loci on chromosome 3p. This report delimits the MRT2A minimal critical region to 4.2 Mb between loci D3S3630 and D3S1304. This interval contains nine genes (IL5RA, TRNT1, LRRN1, SETMAR, SUMF1, ITPR1, BHLHB2, EDEM, and MRPS36P1). The results suggest that a mutation does not exist in these genes and that an unknown transcript in the region contributes to the cognitive deficits in NSMR.
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PMID:Candidate genes for recessive non-syndromic mental retardation on chromosome 3p (MRT2A). 1515 10

A nonsense mutation (R419X) in the human cereblon gene [mutation (mut) CRBN] causes a mild type of autosomal recessive nonsyndromal mental retardation (ARNSMR). CRBN, a cytosolic protein, regulates the assembly and neuronal surface expression of large-conductance Ca(2+)-activated K(+) channels (BK(Ca)) in brain regions involved in memory and learning. Using the real-time quantitative polymerase chain reaction, we show that mut CRBN disturbs the development of adult brain BK(Ca) isoforms. These changes are predicted to result in BK(Ca) channels with a higher intracellular Ca(2+) sensitivity, faster activation, and slower deactivation kinetics. Such alterations may contribute to cognitive impairments in patients with mild ARNSMR.
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PMID:Dysregulation of large-conductance Ca2+-activated K+ channel expression in nonsyndromal mental retardation due to a cereblon p.R419X mutation. 1841 9

Recent studies have shown that autosomal recessive mental retardation (ARMR) is extremely heterogeneous, and there is reason to believe that the number of underlying gene defects goes into the thousands. To date, however, only four genes have been implicated in nonsyndromic ARMR (NS-ARMR): PRSS12 (neurotrypsin), CRBN (cereblon), CC2D1A, and GRIK2. As part of an ongoing systematic study aiming to identify ARMR genes, we investigated a large consanguineous family comprising seven patients with nonsyndromic ARMR in four sibships. Genome-wide SNP typing enabled us to map the relevant genetic defect to a 4.6 Mbp interval on chromosome 8. Haplotype analyses and copy-number studies led to the identification of a homozygous deletion partly removing TUSC3 (N33) in all patients. All obligate carriers of this family were heterozygous, but none of 192 unrelated healthy individuals from the same population carried this deletion. We excluded other disease-causing mutations in the coding regions of all genes within the linkage interval by sequencing; moreover, we verified the complete absence of a functional TUSC3 transcript in all patients through RT-PCR. TUSC3 is thought to encode a subunit of the endoplasmic reticulum-bound oligosaccharyltransferase complex that catalyzes a pivotal step in the protein N-glycosylation process. Our data suggest that in contrast to other genetic defects of glycosylation, inactivation of TUSC3 causes nonsyndromic MR, a conclusion that is supported by a separate report in this issue of AJHG. TUSC3 is only the fifth gene implicated in NS-ARMR and the first for which mutations have been reported in more than one family.
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PMID:A defect in the TUSC3 gene is associated with autosomal recessive mental retardation. 1845 89

The 3p deletion syndrome is a rare disorder caused by deletions of different sizes in the 3p25-pter region. It is characterized by growth retardation, developmental delay, mental retardation, dysmorphism, microcephaly, and ptosis. The phenotype of individuals with deletions varies from normal to severe. Most cases occur de novo, but a few familial cases have been reported. We describe two families with terminal 3p deletions and extremely variable clinical features. In family A, the mother and daughter were extremely mildly affected whereas the son had more severe clinical features. In family B, the mother was normal and her son was affected, having some symptoms that had not been described in the 3p deletion syndrome before. The deletions were characterized by genome-wide SNP array analysis and were 9 and 1.1 Mb in size. Sequencing analysis of the CHL1, CNTN4, and CRBN genes did not reveal any masked recessive alleles that might explain the more severe phenotypes in the probands. In family A, the 9 Mb deletion can be considered causal for the 3p deletion syndrome in the proband, but the extremely mild phenotype in the other family members remains unexplained. In family B, the 1.1 Mb terminal deletion encompasses only the CHL1 gene, which is insufficient to cause 3p deletion symptoms; thus the clinical features observed in this family may have a different cause. The variable penetrance of 3p deletions creates challenges in genetic counseling, as the phenotype of the offspring cannot be predicted based on chromosomal and/or genome-wide array analytical findings.
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PMID:Terminal 3p deletions in two families--correlation between molecular karyotype and phenotype. 2010 86

Cereblon is a protein encoded by the CRBN gene, which has been associated with human autosomal recessive nonsyndromic mental retardation. However, little is known about the regulation of CRBN expression. Following exposure of mouse neuroblastoma N2A cells to hypoxia/reoxygenation (H/R), mRNA and protein expression of CRBN were increased. To better understand how CRBN expression is regulated, the promoter region of the mouse CRBN gene was characterized functionally. Deletion mutations and site-directed mutagenesis led to the identification of a functional NF-E2-related factor 2 (Nrf2)-binding site. Electrophoretic mobility shift analysis indicated that Nrf2 binds to a putative binding site in the CRBN promoter. Nrf2 overexpression and tert-butylhydroquinone treatment enhanced CRBN protein expression. These results imply that Nrf2 stimulates CRBN gene transcription under H/R conditions in neuronal cells.
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PMID:Induction of cereblon by NF-E2-related factor 2 in neuroblastoma cells exposed to hypoxia-reoxygenation. 2069 58