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.
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).
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).
Cognitive impairment in Gdi1-deficient mice is associated with altered synaptic vesicle pools and short-term synaptic plasticity, and can be corrected by appropriate learning training.
Our data further confirm the importance and usefulness of linkage studies for gene mapping in MRX families and demonstrate that IL1RAPL1 plays an important role in the etiology of MRX.
Our data further confirm the importance and usefulness of linkage studies for gene mapping in MRX families and demonstrate that IL1RAPL1 plays an important role in the etiology of MRX.