In summary, the IHC analysis of 13,189 prostate cancers revealed that MTAP deficiency is exceedingly rare, that high MTAP expression is a strong and statistically independent marker for poor prognosis in ERG negative cancers, and that ERG activation fully reverses these MTAP effects even linking high MTAP expression to favorable outcome. The gene discussed is MTAP; the disease is Familial prostate cancer.