PTPRN2 and Infertility: A study of 14 heavy-smoking infertile patients, compared to 14 non-smoking fertile men, showed that there was a significant difference in DNA methylation at the level of several CpGs in amplicons related to the PGAM family member 5 (PGAM5), protein tyrosine phosphatase receptor type N2 (PTPRN2), and tyro3 protein tyrosine kinase (TYRO3) genes.