A common sex chromosomal anomaly in males characterized mainly by small testes with tubular hyalinization, azospermia with infertility, slight breast enlargement, elevated urinary gonadotropins, and decreased urinary 17-ketosteroids. Dull mentality has been noted. The affected individuals appear normal after birth, except for small testes. Most characteristic features become evident at adolescence as hypogonadism, gynecomastia, incomplete virilization with variable eunuchoidism, and dull mentality. Without testosterone therapy, most adult patients may become obese. Occasional abnormalities may include cryptorchidism, hypospadias, ataxia, scoliosis during adolescence, and diabetes mellitus in adulthood.