The azoospermia factor (AZF) region of the euchromatin long arm of the Y chromosome. Y chromosome microdeletions are clinically important because they are associated with severe male infertility, and the likelihood of treatment success can be determined by the location of the deletion. Microdeletions in the Y chromosome long arm (Yq) represent the most frequent molecular genetic cause of severe infertility, being detected in 10%–15% of nonobstructive azoospermic and in 5%–10% of severely oligozoospermic patients. Although the genetic pathways and mechanisms of spermatogenic impairment are still largely unknown, three regions, referred to as “azoospermic factors” (AZFa, b and c from proximal to distal), have been identified on Yq.
AZF deletions have a strong connetion with spermatogenic disorder, which may lead to infertility. However, the infertility status caused by AZF deletions may reflect the fact that nature fertilization is hard to occur with low sperm count. Because of that, it is more appropriate to consider AZF deletions as a cause of oligo/azoospermia rahter than a cause of ‘infertility’.
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