Klinefelter syndrome is the most frequent sex chromosome anomaly. Affected
men characteristically present a tail stature, eunuchoid contours with femi
nine fat distribution, gynecomastia, hypogonadism, infertility, and behavio
ral and psychiatric disorders. Diagnosis is confirmed by karyotype, which d
emonstrates an extra X chromosome. Treatment is mainly directed toward appr
opriate defeminization. Current treatment consists of testosterone replacem
ent therapy and surgical correction of gynecomastia.