Azoospermia Factor a (AZFa) sub-region of human Y-chromosome: A review

•This review paper aims to describe Y-linked AZFa sub-region genes.•Deletion mechanism and genotype phenotype correlation of AZFa is highlighted.•AZFa sub-region microdeletions are rare but have severe consequences.•AZFa sub-region micodeletions is associated with Sertoli-Cell Only syndrome.

Yq microdeletion is one of the well-known genetic causes of infertility in males which results in spermatogenetic impairment. Among the three regions (AZFa, AZFb and AZFc), deletion in Azoospermia Factor a (AZFa) sub-region of the human Y-chromosome considered to have most severe outcome and may cause spermatogenic failure where Sertoli-Cell Only (SCO) syndrome occur in clinically tested testis. Because of the deletion, men may not form or able to keep up the nascent germ cells cohort during adolescence and after that. The AZFa sub-region contains mainly three candidate genes, USP9Y (Ubiquitin specific peptidase 9, Y-linked), DBY (DEAD/H Box 3, Y-linked) and UTY (Ubiquitously Transcribed Tetratricopeptide Repeat Containing, Y-Linked) whose defined role are unknown. This review article makes understand about the deletion mechanism and all the three genes of AZFa sub-region related to infertility in men.