AR and Familial prostate cancer: The androgen receptor (AR) is a ligand-dependent transcription factor and belongs to the family of steroid receptors, which is consisted of DNA-binding domain (DBD), carboxy-terminal ligand-binding domain (LBD), NTD (N-terminal domain) and hinge region of the AR In prostate cancer, the LBD is the most frequent site of gain-of function mutations.