Klinefelter's syndrome: a condition identified by a chromosomal anomaly in morphologic males with the pathognomonic symptoms of a small penis, small testes, sterility, and in some cases gynecomastia. The basic genetic defect is an extra sex chromosome with a total count of 47,XXY. Variants of the syndrome are characterized by more than one extra X chromosome, e.g., 48,XXXY. The secondary sex characteristics are usually weakly developed and do not respond well to treatment with male sex hormone.

Dictionary of Sexology Project: Main Index