15th April 2024

Background

Epidemiology

Klinefelter’s is the most common cause of congenital primary hypogonadism associated with chromosomal abnormalities occurring in 1 out of every 500-700 male neonates with a prevalence at adulthood of 1 out of 2500 males the lower prevalence of Klinefelter’s at adulthood is thought to be due to the condition being ignored or underdiagnosed.

Aetiology

Klinefelter’s occurs due to one or more extra X chromosomes as a result of either maternal or paternal meiotic non-disjunction, 90% of Klinefelter’s occurs due to the 47, XXY karyotype with the remaining 10% due to mosaic Klinefelter’s (47, XXY/46, XY) with some patients having more than one extra X chromosome (48, XXXY/49XXXXY).