[XYY syndrome. Report of a case].

A sixteen year old boy was admitted to our department for delayed puberty. The personal history was not significant and physical examination revealed only a genital hypogonadism. The endocrinology study of the patient showed a hypogonadotropic hypogonadism. The IQ was low. The personality showed infantilism and aggressive impulses. A karyotype revealed 47,XYY. We discuss here the clinical implications of the case.