Klinefelter’s syndrome

Klinefelter’s syndrome is the most common sex chromosome disorder in man and a relatively common cause of male infertility and hypogonadism ( Anders Bojesen et al 2011 )

How common -Only men are affected First defined in 1942 by Harry Klinefelter in males who had small testes , gynaecomastia , and no ability for spermatogenesis ( Boston , Massachusetts ) Most common sex chromosome disorder due an extra X chromosome which can be inherited from either parent KS affects all racial groups and ethnicities equally KS has an estimated prevalence of between 1: 500 to 1: 1000 males Underdiagnosis is common and is widely reported in literature ( 50-60 % of cases ) Mean age of diagnosis is in mid 30s KS is responsible for 3 % of male infertility KS is common in infertile men with oligospermia or azoospermia ( 5 % to 10 % ) Most frequent form of male hypogonadism.

Karyotypes -47 , XXY usually called the classic type is the most common seen in 80 % to 90 % of KS cases.

Rest 10 % to 20 % may have 46 XY / 47 , XXY Mosaic form ( some cells have extra X chromosome and...