Y-chromosome microdeletion

Y-chromosome microdeletions are small missing segments of the Y chromosome in regions called AZFa, AZFb and AZFc that contain genes important for sperm production. They are found in a proportion of men with severe oligozoospermia or non-obstructive azoospermia and are tested for using a specific genetic blood test, usually alongside karyotype testing. The region affected matters for planning: deletions in AZFa or AZFb are generally associated with a very low chance of finding sperm on surgical retrieval, while men with AZFc deletions more often have sperm found on testicular sperm extraction, though this is not guaranteed. If sperm are retrieved and used for ICSI, any resulting sons will inherit the same microdeletion, so genetic counselling is recommended before proceeding.

Also known as: AZFa, AZFb, AZFc, Y chromosome deletion

Last reviewed: 9 September 2026. Written by the Antega Editorial Team. General information only — always follow the advice of your own clinic, doctor or pharmacist.