ABSTRACT
Worldwide, infertility affects 10%–15% of couples, with 30%–40% being due to the male partner. Idiopathic infertility makes up approximately 15% of male-infertility cases. Among infertile men, the most common sex-chromosome abnormality (affecting 3%–4%) is Klinefelter syndrome (KS). KS can be characterized by azoospermia (the complete absence of sperm within the ejaculate), seminiferous tubule dysgenesis, small testes, elevated serum gonadotrophin concentrations, and hypogonadism. The prevalence of KS is estimated to be 1 in every 650 newborn males, with 10% detected prenatally, 3% detected due to behavioral problems or developmental delays, 2% detected due to gynecomastia or delayed puberty, and 17% diagnosed in adulthood due to infertility or hypogonadism. Males with KS are generally described as having a tall stature; long legs with a comparatively short trunk; small, firm testes; hypogonadism; and azoospermia or severe oligozoospermia. The first presentation of men with KS is most commonly infertility.
