Fragile X chromosome in institutionalized male adults with mental retardation

A clinical and cytogenetical study of mentally retarded male adults with an IQ of below 35 has been carried out in the Ranzan Colony for Mental Retardates, Saitama, Japan. The study showed one fragile X-positive retardate with IQ 23 in the 53 residential retarded patients, giving a hemizygote prevalence of 1.9% (1/53). Macroorchidism and elongated ears, practical markers for the clinical diagnosis of fragile X-linked mental retardation, were also detected in this 43-year-old subject with fra(X)(q27.3). He is amiable and no autistic behavior has been observed. The subject, however, has been suffering from epilepsy since childhood and has cataract in both eyes.