Marker X syndrome in an oriental family with probable transmission by a normal male

We report an oriental family with sex-linked mental retardation, macroorchidism, and a marker or fragile site on the X chromosome–mar(X)(q28). The three affected males resemble clinically most previously reported affected Caucasians. The marker was present in four females 40–70 years old, including one with normal intelligence. Transmission of the disorder appears to have taken place through a clinically normal male to his grandson.