In mammals, the Y chromosome directs the development of the testes and plays an important role in spermatogenesis. A high percentage of infertile men have deletions that map to regions of the Y chromosome. The DAZ (deleted in azoospermia) gene cluster maps to the AZFc region and is deleted in many azoospermic and severely oligospermic men. It is thought that the Y chromosomal DAZ gene cluster arose from the transposition, amplification, and pruning of the ancestral autosomal gene DAZL. This gene encodes a RNA-binding protein with two RNP motifs that was originally identified by its interaction with the infertility factors DAZ and DAZL.[7]
