If the treatment of prostate cancer fails, it progresses to a new form known as castration-resistant prostate cancer (CRPC) that is a problematic issue in clinical course and some major genes including androgen receptor (AR), TP53, RB1, PTEN and DNA damage repair (DDR) undergo mutations in this form of prostate cancer [12–14]. The gene discussed is PTEN; the disease is Familial prostate cancer.