About 30% of the mutations causing nonsyndromic X-linked mental retardation (MRX) are thought to be located in Xp11 and in the pericentromeric region, with a particular clustering of gene defects in a 7.4 Mb interval flanked by the genes ELK1 and ALAS2.
About 30% of the mutations causing nonsyndromic X-linked mental retardation (MRX) are thought to be located in Xp11 and in the pericentromeric region, with a particular clustering of gene defects in a 7.4 Mb interval flanked by the genes ELK1 and ALAS2.
This finding is in agreement with the hypothesis that the incidence of intermediate FMR1 alleles in MRX populations does not seem to be higher than in control populations, and it emphasizes the importance of FMRP detection as a diagnostic tool for fragile X syndrome.
RSK4 is completely deleted in eight patients with the contiguous gene syndrome including MRX, partially deleted in a patient with DFN3 and present in patients with an Xq21 deletion and normal intellectual abilities.
RSK4 is completely deleted in eight patients with the contiguous gene syndrome including MRX, partially deleted in a patient with DFN3 and present in patients with an Xq21 deletion and normal intellectual abilities.
DNA investigation established an interstitial deletion in Xp22.3 involving the Kallmann (KAL) gene, the steroid sulfatase (STS) gene and a putative mental retardation locus (MRX).
DNA investigation established an interstitial deletion in Xp22.3 involving the Kallmann (KAL) gene, the steroid sulfatase (STS) gene and a putative mental retardation locus (MRX).
Although an extension of the linkage analysis for MRX35 showed only a minimal overlap with MRX46, it cannot be excluded that the same gene is involved in several of these MRX disorders.
Mutations of oligophrenin 1, one of the first genes identified in nonspecific X-linked mental retardation (MRX), have been described in patients with moderate to severe cognitive impairment and predominant cerebellar hypoplasia, in the vermis.
DNA investigation established an interstitial deletion in Xp22.3 involving the Kallmann (KAL) gene, the steroid sulfatase (STS) gene and a putative mental retardation locus (MRX).
Although genotype-phenotype correlations in male patients with various types of nullisomy for Xp22.3 have assigned a locus for X-linked mental retardation (MRX) to an approximately 3-Mb region between DXS31 and STS, the precise location has not been determined.
Mutations in most of more than 20 known genes causing nonspecific form of X-linked MR (MRX) are very rare and may account for less than 0.5-1% of MR. Linkage studies in extended pedigrees followed by mutational analysis of known MRX genes in the linked interval are often the only way to identify a genetic cause of the disorder.
The 13 MRX genes identified to date account for less than one-fifth of all MRX, suggesting that numerous gene defects cause the disorder in other families.
These findings, with the compelling genetic evidence suggesting the presence in Xq28 of additional genes besides RabGDI1 and FMR2 involved in non-specific X-linked mental retardation (MRX), prompted us to investigate MECP2 in MRX families.
Elucidation of the function of the FMR2 protein as a transcription activator may place FMR2 within the molecular signalling pathways involved in nonspecific X-linked mental retardation (MRX).
These findings, with the compelling genetic evidence suggesting the presence in Xq28 of additional genes besides RabGDI1 and FMR2 involved in non-specific X-linked mental retardation (MRX), prompted us to investigate MECP2 in MRX families.
Elucidation of the function of the FMR2 protein as a transcription activator may place FMR2 within the molecular signalling pathways involved in nonspecific X-linked mental retardation (MRX).
So far, seven X-chromosomal genes mutated in nonspecific mental retardation (MRX) have been identified: FMR2, GDI1, RPS6KA3, IL1RAPL, TM4SF2, OPHN1 and PAK3 (refs 2-9).
So far, seven X-chromosomal genes mutated in nonspecific mental retardation (MRX) have been identified: FMR2, GDI1, RPS6KA3, IL1RAPL, TM4SF2, OPHN1 and PAK3 (refs 2-9).
On the other hand, given the considerable genetic heterogeneity in MRX, one should be extremely cautious in using interfamilial linkage data to narrow down the localisation of MRX genes.
A recurrent missense variant in SLC9A7 causes nonsyndromic X-linked intellectual disability with alteration of Golgi acidification and aberrant glycosylation.