Klinefelter syndrome is characterized by small, firm testes, azoospermia (no sperm count), gynecomastia, in men with two or more X chromosomes. The common karyotype is 47,XXY . They have elevated levels of plasma gonadotropins. They have male psychosexual orientation and function sexually as normal men.
It is the most frequent major abnormality of sexual differentiation. This condition exists in roughly 1 out of 1000 males. 1 in 500 males have an extra chromosome but may not have the syndrome.
The syndrome was named after Dr. Harry Klinefelter, who worked with Fuller Albright and first described it in the year 1942.
The principal effects are development of small testicles and reduced fertility.
Before puberty the testes appear normal but are small.
Gynecomastia (enlargement of breasts ) develops during adolescence, is generally bilateral and painless.
Mean body weight is increased due to longer legs.
Obesity and varicose veins occur in one-third to one-half.
Mild mental deficiency, social maladjustment.
Abnormal of thyroid functions, diabetes mellitus, and pulmonary disease may be present.
The risk of breast cancer is 20 times that of normal men (but only about a fifth that in women)
Treatment : Gynecomastia may need surgical treatment. Testosterone injections are needed.