Fragile X Syndrome is the most common inherited cause of mental retardation, and is associated with autism. The fragile X syndrome is a genetic disorder caused by mutation of the FMR1 gene on the X chromosome. Mutation at that site is found in 1 out of about every 4000 males and 1 out of about every 6000 females.
Aside from mental retardation, prominent characteristics of the syndrome include an elongated face, large or protruding ears, large testicles (macroorchidism), and low muscle tone. Behavioral characteristics may include stereotypic movements (e.g., hand-flapping) and atypical social development, particularly shyness and limited eye contact. Some individuals with the fragile X syndrome also meet the diagnostic criteria for autism.
Recent studies have focused on a number of critical areas. The role of FMRP's RNA partners, many of which have now been validated through in vitro assays, is of primary importance. Also being examined is the function the various domains of FMRP, an RNA-binding protein, which is still relatively unknown.
While there is no current cure for the syndrome, there is hope that further understanding of its underlying causes would lead to new therapies. Currently, the syndrome can be treated through behavioral therapy, special education, medication, and when necessary, treatment of physical abnormalities. Persons with the fragile X syndrome in their family histories are advised to seek genetic counseling to assess the likelihood of having children who are affected, and how severe any impairments may be in affected descendants.