Fragile X syndrome (FXS/FXTAS/FXPOI). CGG expansions in the FMR1 gene [1 gene]

Fragile X syndrome occurs in individuals with a complete mutation of the FMR1 gene or another loss-of-function variant and it is almost always characterized in affected males by developmental delay and intellectual disability along with a variety of behavioral problems (autism spectrum disorder is present in 50%-70%). Affected males may have characteristic craniofacial features and medical problems including hypotonia, gastroesophageal reflux, strabismus, seizures, sleep disorders, joint laxity, flat feet, scoliosis, and recurrent otitis media. Adults may have mitral valve prolapse or aortic root dilatation.

1/2,400 to 1/6,000 (ORPHA:908).

Service is recommended to rule out Fragile X syndrome since >99% of affected individuals have an expansion in the 5′ UTR region of CGG trinucleotides (more than 200 repeats), detectable by this service.

The benefits derived from a genetic diagnosis in this context are especially aimed at closing the diagnosis and family genetic counseling.

Service indicated when considering the diagnosis of Fragile X syndrome when evaluating a patient with intellectual disabilities.