CLCN2 and Azoospermia: Moreover, in light of the previously identified association of human CLCN2 gene mutations with male reproductive disorders (Di Bella et al. 2014, Jeworutzki et al. 2021), our findings provide strong evidence suggesting that, in these patients, loss-of-function mutations in the ClC-2 chloride channel result in testosterone deficiency, which may be mechanistically linked to their clinical manifestation of azoospermia and infertility.