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

Linkage studies and cytogenetically visible deletions associated with nonspecific X-linked mental retardation (XLMR) and a specific form of deafness (DFN3) have indicated that the genes responsible for these disorders are located at Xq21. Using DNA probes from this region, we have studied several overlapping deletions spanning different parts of Xq21. This has enabled us to assign the DFN3 gene and a gene for nonspecific XLMR to an interval that encompasses the locus DXS232 and that is flanked by DXS26 and DXS121.
 ...
PMID:Physical fine mapping of genes underlying X-linked deafness and non fra (X)-X-linked mental retardation at Xq21. 151 79

We have found that the microsatellite marker AFM207zg5 (DXS995) maps to all previously described deletions which are associated with X-linked mixed deafness (DFN3) with or without choroideremia and mental retardation. Employing this marker and pHU16 (DXS26) we have identified two partially overlapping yeast artificial chromosome clones which were used to construct a complete 850 kb cosmid contig. Cosmids from this contig have been tested by Southern blot analysis on DNA from 16 unrelated males with X-linked deafness. Two novel microdeletions were detected in patients which exhibit the characteristic DFN3 phenotype. Both deletions are completely contained within one of the known DFN3-deletions, but one of them does not overlap with two previously described deletions in patients with contiguous gene syndromes consisting of DFN3, choroideremia, and mental retardation. Assuming that only a single gene is involved, this suggests that the DFN3 gene spans a chromosomal region of at least 400 kb.
 ...
PMID:X-linked mixed deafness (DFN3): cloning and characterization of the critical region allows the identification of novel microdeletions. 798 85

X-linked syndromes associated with developmental delay and sensorineural hearing loss (SNHL) have been characterized at the molecular level, including Mohr-Tranebjaerg syndrome and Norrie disease. In this study we report on a novel X-linked recessive, congenital syndrome in a family with developmental delay and SNHL that maps to a locus associated with mental retardation (MR) for which no causative gene has been identified. The X-linked recessive inheritance and congenital nature of the syndrome was confirmed by detailed clinical investigation and the family history. Linkage mapping of the X-chromosome was conducted to ascertain the disease locus and candidate genes were screened by direct sequencing and STRP analysis. The recessive syndrome was mapped to Xp11.3-q21.32 and a deletion was identified in a regulatory region upstream of the POU3F4 gene in affected family members. Since mutations in POU3F4 cause deafness at the DFN3 locus, the deletion is the likely cause of the SNHL in this family. The choroideremia (CHM) gene was also screened and a novel missense change was identified. The alteration changes the serine residue at position 89 in the Rab escort 1 protein (REP-1) to a cysteine (S89C). Prenylation of Rab proteins was investigated in patients and the location of REP-1 expression in the brain determined. However, subsequent analysis revealed that this change in CHM was polymorphic having no effect on REP-1 function. Although the causative gene at the MR locus in this family has not been identified, there are a number of genes involved in syndromic and nonsyndromic forms of MR that are potential candidates.
 ...
PMID:Molecular characterization of a novel X-linked syndrome involving developmental delay and deafness. 1793 54