MCMDC2 (minichromosome maintenance domain containing 2) is an atypical MCM protein that plays a critical role in meiotic recombination and DNA double-strand break repair 1. The gene is substantially expressed during spermatogenesis 2 and is essential for maintaining fertility in both sexes. Mechanistically, MCMDC2 functions in meiotic processes, including meiotic recombination and associated DNA repair pathways 3. Loss-of-function variants in MCMDC2 disrupt normal meiosis progression 4. Clinical relevance is substantial in reproductive medicine. Biallelic MCMDC2 variants cause meiotic arrest and non-obstructive azoospermia (NOA) in males, with deleterious variants producing either meiotic arrest or hypospermatogenesis depending on the specific mutation 2. In females, pathogenic variants in MCMDC2 contribute to premature ovarian insufficiency (POI), a major cause of early loss of ovarian function and female infertility 3. Notably, all NOA patients with meiotic gene defects, including MCMDC2 mutations, showed unsuccessful sperm retrieval, indicating genetic diagnosis could help avoid unsuccessful surgical interventions 4. Additionally, MCMDC2 has been identified in novel fusion transcripts in adenoid cystic carcinoma, suggesting broader roles in genomic stability 5.