Zmynd15, zinc finger MYND-type containing 15, acts as a histone deacetylase-dependent transcriptional repressor. It controls the normal temporal expression of haploid cell genes during spermiogenesis, which is a crucial process in spermatogenesis where spermatids develop into spermatozoa. Zmynd15 is essential for male fertility as it may regulate spermatogenesis by interacting with key molecules like DPY19L2, AKAP4, and FSIP2 involved in sperm development, and might also mediate the expression of the autophagy-associated protein SPATA33 to maintain sperm individualisation and unnecessary cytoplasm removal [4,1].

In mouse models, inactivation of Zmynd15 results in early activation of transcription of numerous important haploid genes such as Prm1, Tnp1, Spem1, and Catpser3, depletion of late spermatids, and male infertility, indicating its essential role in sperm production [4].

In human studies, sequencing in infertile men has identified various Zmynd15 variants. For example, in a cohort of infertile Chinese men, 31 Zmynd15 variants were found in 227 patients, with 3 deleterious biallelic variants detected in 3 affected individuals with oligoasthenoteratozoospermia, showing a biallelic pathogenic mutation frequency of 1.3% [1]. Three novel homozygous truncating variants in Zmynd15 were identified in 1.37% of unrelated patients with severe oligozoospermia [2]. A homozygous loss-of-function variant in Zmynd15 was found in a subject with severe oligozoospermia and a phenotypic diagnosis of macrozoospermia [3]. Also, truncating mutations in Zmynd15 were identified in a family with idiopathic azoospermia [5].

In conclusion, Zmynd15 is essential for spermiogenesis and male fertility. Its inactivation in mouse models and identification of variants in human infertile patients highlight its significance in male reproductive diseases. The study of Zmynd15 using gene knockout models has provided insights into the genetic basis of male infertility, potentially guiding genetic counseling and diagnosis [1,2,3,4,5].