Genetic and functional analysis reveals novel mutations in meiotic genes underlying non-obstructive azoospermia.

Objective: To identify novel pathogenic mutations in meiotic genes underlying non-obstructive azoospermia (NOA) through whole-exome sequencing analysis.

Methods: Whole-exome sequencing was performed on 31 NOA patients. Novel variants were identified through bioinformatic analysis and validated by Sanger sequencing. The pathogenicity of variants was assessed through functional studies including protein structural analysis, conservation analysis, and minigene splicing assays.

Results: We identified novel pathogenic mutations in four meiotic genes. Most significantly, we discovered the first human case of a homozygous nonsense mutation in MAEL (c.514C > T, p.Gln172Ter) in a patient from a consanguineous family. Additionally, we found novel compound heterozygous mutations in MSH5 (c.648-2A > G and c.1133T > C) and REC114 (c.659_706dup and c.123C > A), and a heterozygous splice-site mutation in DMRT1 (c.968-2A > G). Functional analyses revealed that these mutations disrupted critical meiotic processes through aberrant splicing, protein truncation, or structural alterations.

Conclusions: Our findings expand the mutation spectrum of meiotic genes in male infertility and provide new insights into the genetic basis of spermatogenic failure. The identification of novel mutations, particularly the first reported homozygous MAEL mutation, enhances our understanding of meiotic arrest in human spermatogenesis and provides valuable information for genetic counseling.