TXNDC2 and Azoospermia: TXNDC2, along with protamine 1 and 2 (PRM1 and PRM2), was significantly decreased in patients with different patterns of NOA compared to OA patients, suggesting that TXNDC2, PRM1, and PRM2 have a robust power to predict sperm retrieval and are correlated with phenotypes of severe azoospermia [78].