Klinefelter syndrome

Klinefelter syndrome affects n1:660 men, making it the most common sex=chromosome disorder in man, and is a common cause of infertility. The syndrome was named after Harry F. Klinefelter.

It is a chromosomal disorder (47XXY and variants, e.g. 46XY/47XXY mosaicism), i.e. a male with an extra X chromosome. There is both a loss of Leydig cells and seminiferous tubular dysgenesis.

 The presence of Y chromosome explains the male gonadal differentiation with subsequent testosterone and AMH production and the therefore the individual are phenotypically male.

Patients usually present in adolescence with poor sexual development, small or undescended testes, gynaecomastia or infertility.

Teenagers and young men with Klinefelter’s syndrome have a variety of problems, the most severe of which are a tendency toward the body shape of a woman, lack of muscle mass, abnormal breast development, behavioral problems and is some cases, reduced intelligence.
 Klinefelter syndrome