SPEM1 (spermatid maturation 1) is essential for proper cytoplasm removal and sperm maturation during spermatogenesis. The protein functions in late-stage spermiogenesis, where it interacts with junction plakoglobin to facilitate proper sperm morphology and motility 1. SPEM1 is involved in flagellar assembly and sperm individualization, processes critical for producing functional spermatozoa 2. SPEM1 dysfunction causes teratozoospermia characterized by morphological defects including coiled sperm tails and excessive residual cytoplasm 34. A heterozygous SPEM1 mutation (c.826C>T, Arg276Trp) has been identified as a pathogenic variant causing coiled sperm tail defects 3. SPEM1 mRNA expression is tightly regulated during spermatid development, with phosphorylated GRTH playing a role in stabilizing SPEM1 transcripts within chr17 bodies 5. Clinically, SPEM1 has significant diagnostic value in male infertility assessment. Among testis-specific markers, SPEM1 shows superior predictive power (96% sensitivity, 85% specificity) for predicting sperm retrieval success in azoospermic men undergoing testicular sperm extraction 6. SPEM1 appears as a robust protein marker for evaluating sperm quality and understanding the molecular basis of male infertility phenotypes 27.