TSNAXIP1 (translin associated factor X interacting protein 1) is a testis-expressed protein that plays a critical role in male fertility and spermatogenesis. Located on chromosome 16, TSNAXIP1 functions as a binding partner of TRAX (translin-associated factor X) in the cytoplasm 1. The protein colocalizes with TRAX at perinuclear organelles during germ cell development 1. TSNAXIP1 is essential for proper sperm head morphogenesis and male fertility; knockout mice demonstrate reduced testis size, lower sperm counts, and characteristic sperm head malformations including abnormal flower-shaped head morphology and defective neck anchorage 2. TSNAXIP1 is highly conserved between mouse and human, suggesting relevance to human infertility 2. Beyond reproductive function, TSNAXIP1 has been implicated in psychiatric genetics—a gene cluster on chromosome 16 containing TSNAXIP1 showed significant multivariate gene-environment interactions with polysubstance dependence and suicidal ideation (p = 2.13 × 10-7) 3. These findings establish TSNAXIP1 as a potential causative gene for human male infertility and suggest broader biological roles in cellular processes.