Y chromosome and male fertility: the AZF genes and their deletion

: The Y chromosome plays a crucial role in male fertility as it carries genes that are essential for testis development and spermatogenesis. The Yq gene content can be disrupted by microdeletions of AZoospermia Factor (AZF) regions, leading to impaired sperm production and influencing the likelihood of successful testicular sperm extraction (TESE) in azoospermic men. Here, we review the available evidence on TESE outcomes according to deletion type and integrate it with our original data. Our findings confirm that among complete AZF deletions, only AZFc deletions are associated with positive TESE outcomes, resulting in an overall success rate of 58.85%. Conversely, the semen and testicular phenotypes vary considerably in cases of partial AZFa and AZFb deletions. For this reason, accurately defining the extent of these deletions-and thereby distinguishing between complete and partial deletions-is of pivotal importance. AZF screening is the only currently available pre-TESE predictive test. Finally, we address the clinical implications of the various AZF deletions, including genetic counselling.