However, sperm chromatin fragmentation (SCF) assessment by the TUNEL assay showed elevated SCF, suggesting that PRB1 alterations carried by spermatozoa from infertile men with obstructive azoospermia, acquired by vasectomy, may affect their ability to withstand the action of oxygen free radicals, subsequently impairing embryo development and precluding these patients from achieving pregnancy [47]. This evidence concerns the gene KITLG and Azoospermia.