Molecular Testing for Fragile X Syndrome (FRAXA/FRAXE)
Fragile X syndrome is the most common genetic disorder associated with intellectual disability. It is characterized by autistic-like behaviors, moderate to severe intellectual disability, and behavioral problems.
Almost exclusively transmitted from mother to son, it occurs at a frequency of 1 in 1,000–2,000 male births. This is an X-linked genetic abnormality in which the mother is a carrier and passes the disorder to her sons.
The genetic cause of the syndrome is the expansion of CGG trinucleotide repeats in the FMR1 gene located at the FRAXA site on the X chromosome (Xq27.3). A smaller number of individuals with moderate intellectual disability have expansions in the FMR2 gene at the FRAXE site on the X chromosome.
Affected males typically show moderate to severe intellectual disability, while females may also be affected, usually with mild intellectual disability. Behavioral problems and language delays are common features of the syndrome.
Additionally, in 6% of women with premature ovarian insufficiency (ovarian failure in women under 40 years old), a mutation in the FMR1 gene has been detected.
Sample Type: Peripheral blood
Turnaround Time: 2 weeks