Beside FMR1, in families with X-linked mental retardation (XLMR), the ARX dysfunction was demonstrated to be among the most frequent causes of this heterogeneous group of disorders.
Our data indicate that the frequency of SLC6A8 mutations in the XLMR population is close to that of CGG expansions in FMR1, the gene responsible for fragile-X syndrome.
Fragile X syndrome, a form of X-linked mental retardation, results from the hyperexpansion of a CGG trinucleotide repeat located in the 5' untranslated region of the fragile X mental retardation (FMR1) gene.
Fragile-X syndrome is due to an expression of CGG trinucleotide repeats in the 5' untranslated region of the FMR1 gene and it is the most common cause of heritable X-linked mental retardation.
The fragile X syndrome is an X-linked mental retardation disorder caused by an expanded CGG repeat in the first exon of the fragile X mental retardation (FMR1) gene.