Concerning the role of X-inactivation and DNA methylation in fragile X syndrome.
Elucidation of the role of DNA methylation in X chromosome inactivation along with recent studies of the fragile X mutation suggests that DNA methylation is likely to be a late event in the pathogenesis of the fragile X syndrome. Thus far, the evidence does not support suggestions that an impediment to X reactivation and failure to demethylate the inactive X in oocytes is responsible for silencing the fragile X. The role of DNA methylation is probably secondary to amplification of the CGG repeat to a critical size whether on active or inactive X. Further studies are needed to determine if late replication of the inactive X predisposes the locus on that chromosome to more extensive amplification.
Migeon
B R
BR
Department of Pediatrics, The Johns Hopkins University School of Medicine, Baltimore, Maryland.
D004247:DNA / Q000737:chemistry / Q000235:genetics; D004303:Dosage Compensation, Genetic; D005260:Female; D005600:Fragile X Syndrome / Q000209:etiology / Q000235:genetics*; D006801:Humans; D008297:Male; D008745:Methylation; D008957:Models, Genetic; D009866:Oogenesis / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid
D004247:DNA