Molecular pathology of the fragile X syndrome.
Fragile X syndrome is the most common form of familial mental retardation (one in 1250 males and one in 2500 females, characterized by prominent dysmorphic features, macro-orchidism, and varying degrees of mental retardation. Diagnosis of this syndrome has relied on cytogenetic demonstration of the fragile site at position Xq27.3. A gene associated with the fragile X syndrome, FMR-1, has been isolated and mapped to the region of the X chromosome that corresponds to the region of the fragile site. Expansion of a trinucleotide repeat, CGG, and abnormal methylation of a CpG island account for the majority of mutations identified in FMR-1. These molecular characteristics have greatly enhanced the identification of affected individuals and carriers of the premutation who were not detected cytogenetically.
Tsongalis
G J
GJ
Department of Hospital Laboratories and Pathology, University of North Carolina Hospitals, Chapel Hill.
Silverman
L M
LM
D015139:Blotting, Southern; D003582:Cytogenetics; D005260:Female; D005600:Fragile X Syndrome / Q000175:diagnosis / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree