DAZ4 is an RNA-binding protein essential for spermatogenesis, functioning as a translation regulator by binding to the 3'-UTR of mRNAs to stabilize and activate their translation 1. DAZ4 exists as one of four paralogous copies (DAZ1-DAZ4) on the Y chrY's AZFc region, with functional redundancy among copies 2. Loss of DAZ4 alone through partial deletions shows variable effects on fertility: DAZ4 deletion in isolation is relatively frequent in both fertile and infertile men, though removing DAZ4 appears more common in oligospermic than normospermic men 1. However, simultaneous deletion of both DAZ2 and DAZ4 copies significantly associates with male infertility 1, suggesting synergistic effects. In contrast, DAZ1/DAZ2 deletions constitute higher risk factors for spermatogenic failure 34, while DAZ3/DAZ4 deletions alone have minimal fertility impact 24. Complete AZFc deletions removing all DAZ copies cause severe oligozoospermia or azoospermia 3. DAZ4 deletions are classified as spermatogenic failure Y-linked 2 when pathogenic. Clinical significance lies in genetic screening of infertile men, particularly identifying combined DAZ2/DAZ4 loss as a risk factor warranting counseling.