In addition, the role of circadian genes was investigated in prostate cancer by Zhu et al. in an American population-based case-control study among Caucasian men whereby 17 single nucleotide polymorphisms (SNP)s located in three core genes (i.e., ARNTL, CSNKIE, and NPAS2) were identified and significantly related to prostate cancer [28]. The gene discussed is NPAS2; the disease is Familial prostate cancer.