To study how the detected differences in AR variant expression between PC stages are translated to the protein level, we performed immunohistochemistry against AR-V7 with tumour microarrays of hormone-naïve PC from prostatectomies (n = 146), locally recurrent CRPCs (n = 97) and metastatic CRPC samples (103 metastases in total from 31 patients; 1–5 metastases per patient). The gene discussed is AR; the disease is pachyonychia congenita.