Consideration of connective tissue dysfunction in the fragile X syndrome.

Eleven cytogenetically documented patients with the fragile X syndrome were evaluated for hyperextensibility of the finger joints and the presence of other manifestations of connective tissue dysfunction. All of the patients had hyperextensibility of several finger joints and many had features such as flat feet, highly arched palate and the ability to voluntarily dislocate finger joints. These traits, particularly hyperextensibility of the joints, are a useful aid in the clinical diagnosis of the fragile X syndrome.