Klinefelter syndrome

Klinefelter syndrome (47,XXY) is a common genetic cause of non-obstructive azoospermia, often diagnosed during fertility investigation. Sperm can be retrieved by micro-TESE in a meaningful proportion of men, particularly at younger ages. Testosterone therapy suppresses any remaining production, so fertility should be discussed before starting it.

Also known as: 47 XXY, XXY

Last reviewed: 10 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.