Klinefelter’s syndrome is a genetic condition that only affects males. It is congenital, which means that the condition is present from birth. Klinefelter’s syndrome is one of the most common genetic disorders, affecting about one in 650 men, but it is believed that many men with Klinefelter’s syndrome are never diagnosed.

In this overview Professor Rob McLachlan discusses Klinefelter’s syndrome. He explains how it can present differently in each individual but a common feature is that all men with Klinefelter’s syndrome will have small testes.