Diagnosis of the fragile X syndrome (Martin-Bell syndrome). Clinical findings in 27 males with the fragile site at Xq28.

The results of a clinical investigation of 27 males with the fragile X are reported; the age range was from 1 to 77 years. The medical history in pre-, peri- and early post-natal life was unremarkable. Birth weights tended to be above average. In infancy hypotonia and a large head were often found, together with retarded development. Macroorchidism was almost uniformly found after puberty, but apparently not often before. The facial features in the grown-up males were characteristic, confirming previous reports. Minor abnormalities of feet and hands were seen. Mental retardation was often in the moderate range, but all degrees were seen. Psychiatric symptoms were frequently seen, and one child was diagnosed as autistic. A developmental profile is outlined.