TMPRSS2 and Familial prostate cancer: About 50% of all prostate cancers carry a gene fusion linking the androgen‐regulated serine protease TMPRSS2 with the ETS‐transcription factor ERG resulting in an androgen‐related overexpression of ERG (Brase et al., 2011; Tomlins et al., 2005; Weischenfeldt et al., 2013).