IQCF1 (IQ motif containing F1) is an acrosomal protein essential for male fertility through its involvement in sperm capacitation and the acrosome reaction. 1 IQCF1 is localized to the acrosome of spermatozoa and spermatids, where its expression correlates with spermatogenic capacity. 1 Mechanistically, IQCF1 interacts with calmodulin and participates in tyrosine phosphorylation of sperm proteins during capacitation, a critical process for fertilization competence. 1 IQCF1-knockout mice demonstrated significantly reduced fertility (p = 0.0057) due to impaired sperm motility (p = 0.0094) and diminished acrosome reaction capability (p = 0.0093). 1 Clinically, IQCF1 dysfunction is implicated in male infertility; altered IQCF1 expression (8-fold downregulation) was observed in men with Y chromosome 3 microdeletions and elevated sperm DNA fragmentation who experienced assisted reproductive technique failures. 2 Additionally, IQCF1 amplifications appear more frequent in prostate tumors from men of Middle Eastern ancestry compared to European ancestry populations, suggesting potential cancer-associated genomic variations. 3 These findings establish IQCF1 as a critical fertility determinant whose dysfunction directly contributes to reproductive failure.