ABSTRACT
Fragile X-associated disorders are a family of X-linked disorders caused by expansions of a CGG repetitive sequence in the Fragile X Mental Retardation 1 (FMR1) gene, which codes for the Fragile X Mental Retardation Protein (FMRP). The FMR1 gene and it expansions can be classified according to CGG repeat sizes. The FMR1 PM confers health risks that are distinct from fragile X syndrome. Genetic testing for an FMR1 premutation was undertaken at the age of 60 years when his grandson was diagnosed with fragile X syndrome. A number of studies suggest that structural and functional brain changes observed in carriers of the PM may be associated with FMR1 molecular measures including greater CGG repeat length and elevated FMR1 mRNA levels. Fragile X-associated tremor ataxia syndrome is an inherited neurodegenerative disorder affecting up to 45% of men and 8–16% of women who carry premutation expansions of the FMR1 gene.
