Gecz J
Department of Cytogenetics and Molecular Genetics, Centre for Medical Genetics, Women's and Children's Hospital, North Adelaide, SA, Australia.
Ann Hum Genet. 2000 Mar;64(Pt 2):95-106. doi: 10.1017/S0003480000007983.
FRAXE fragile site associated mental retardation remains unique among X-linked mental retardation phenotypes due to its very mild to borderline nature (50< IQ< 85). It is the most prevalent form of non-specific X-linked mental retardation so far delineated, with an estimated incidence of at least 1/50-100,000 males, and with more than 50 families known worldwide. The FRAXE site is within, or immediately adjacent to, the 5' untranslated region of the FMR2 gene. Hyperexpansion of the FRAXE CCG repeat silences transcription of the gene. The structure of FMR2 has been characterized, but its function remains unknown. Gene localizations for numerous (> 75) large families with non-specific X-linked mental retardation (MRX) have been determined so far. Recently the molecular basis for some of them has been unravelled by identification of the responsible genes, which participate in complex common signalling pathways. This review summarises the new data on FRAXE associated mental retardation and the FMR2 gene in the light of the recent discoveries of new genes responsible for other forms of non-specific X-linked mental retardation.
FRAXE脆性位点相关的智力发育迟缓在X连锁智力发育迟缓表型中仍然独具特色，因为其症状非常轻微至临界状态（智商50<85）。它是迄今为止所描述的最常见的非特异性X连锁智力发育迟缓形式，估计发病率至少为1/50 - 100,000男性，全球已知超过50个家系。FRAXE位点位于FMR2基因的5'非翻译区内或紧邻该区域。FRAXE CCG重复序列的过度扩增会使该基因的转录沉默。FMR2的结构已得到表征，但其功能仍然未知。到目前为止，已经确定了众多（>75个）患有非特异性X连锁智力发育迟缓（MRX）的大家庭的基因定位。最近，通过鉴定参与复杂常见信号通路的致病基因，其中一些疾病的分子基础已被揭示。鉴于最近发现了导致其他形式非特异性X连锁智力发育迟缓的新基因，本综述总结了关于FRAXE相关智力发育迟缓及FMR2基因的新数据。
