Introduction
Fragile X syndrome is the most common cause of inherited mental retardation, seen in approximately one in 1,200 males and one in 2,500 females. Males with fragile X syndrome usually have mental retardation and often exhibit characteristic physical features and behavior [Hagerman and Silverman, 1991; Warren and Nelson, 1994]. Affected females exhibit a similar, but usually less severe phenotype.
The diagnosis of fragile X syndrome was originally based on the expression of a folate-sensitive fragile site at Xq27.3 (FRAXA) induced in cell culture under conditions of folate depriv…
