Klinefelter's Syndrome

Most common genetic cause of hypogonadism, only men affected

Aetiology

  • Genetic but not inherited - caused by nondisjunction
  • Usually genotype 47 XXY, can have 46 XY/47 XXY mosaicism

Clinical presentation

  • Presentation variable and therefore diagnosis can be missed or late
  • Affected men are typically infertile (due to tubular damage) and have small, firm testes

Investigations

  • Karyotyping

Complications

  • Increased incidence of cryptorchidism, learning disability and psychosocial issues
  • Increased risk of breast cancer and non-Hodgkin lymphoma