Advances in non-essential testis-enriched genes for human and mouse spermatogenesis

Spermatogenesis is a highly complex cellular differentiation process. Recent advances employing knockout or knock-in mouse models have functionally characterized more than 700 genes as essential for male fertility maintenance. Paradoxically, emerging evidence reveals that a substantial proportion of the continuously expanding catalog of testis-enriched genes exhibits biological dispensability for normal sperm production. To systematically catalog non-essential testis-enriched genes in murine spermatogenesis, we performed a comprehensive PubMed literature review encompassing studies published up to 1 August 2025. Through stringent inclusion criteria, this analysis consolidates data from 83 publications that identified 261 testis-enriched genes demonstrated to be non-essential for spermatogenesis. We further categorize these genes by their familial relationships and explore potential explanations for the fertile phenotype observed in these knockout models, including genetic redundancy, compensatory mechanisms, differences in knockout strategies, and environmental influences. This review provides a valuable resource to avoid unnecessary expenditures and effort by research teams.