CMTM5, a member of the human CKLF-like MARVEL transmembrane domain containing family, has recently been recognized as a novel tumour suppressor, as evidenced by reduced or silenced expression in most cancers including cervical carcinoma [8], pancreatic cancer [9], myeloid leukemia [10], ovarian cancer [11], OSCC [12] and prostate cancer [13]. This evidence concerns the gene CMTM5 and Familial prostate cancer.