TDRD12 (tudor domain containing 12) is an ATP-binding RNA helicase essential for male fertility and germline integrity. Functionally, TDRD12 operates within the piRNA (PIWI-interacting RNA) metabolic pathway to silence transposable elements during spermatogenesis 1. The protein acts via the PET complex to facilitate secondary piRNA biogenesis and promote PIWIL-mediated transposon repression through DNA methylation 2. TDRD12 expression is developmentally regulated, showing particularly high levels during spermatogenesis stages 2. Clinically, TDRD12 mutations cause distinct male infertility phenotypes depending on which protein domain is affected 1. A frameshift mutation (c.3378dupG) lacking the cysteine-rich domain resulted in teratozoospermia with abnormal sperm morphology and reduced PIWIL1 expression, while a nonsense mutation (c.2463C>G) causing complete protein loss led to azoospermia with germ cell maturation arrest and elevated LINE-1 transposon activation 1. TDRD12 expression is significantly reduced in testicular samples from men with various azoospermia types, particularly in hypospermatogenesis 2. Beyond reproductive function, TDRD12 was identified as a candidate hypomethylated gene in salivary gland adenoid cystic carcinoma 3. These findings establish TDRD12's critical role in transposon silencing and spermatogenesis.