In 40–60% of early prostate cancer patients, genomic aberrations are observed, such as fusion in TMPRSS2-ERG, whereas 5–15% of patients exhibited loss of function mutation in SPOP genes, and 3–5% of patients showed gain-of-function mutations in FOXA1. The androgen receptor gene (AR) alterations are also rarely observed in early prostate cancer [71]. The gene discussed is AR; the disease is prostate cancer.