Dystrophia myotonica in a 47, XXY male.

Classical clinical manifestations of dystrophia myotonica were apparently unaltered by aneuploidy in a 47, XXY male. His extremely eunuchoid habitus may represent a contribution by the point mutation to his Klinefelter's syndrome. Association of the two disorders may be due to factors other than chance. The danger of overlooking Klinefelter's syndrome in males with dystrophia myotonica can be avoided by cytologic studies.