Based on comprehensive epigenetic analyses of benign and malignant prostate tissue samples from multiple independent patient cohorts, we have previously identified and validated CCDC181 (C1orf114) and HAPLN3 as novel diagnostic and/or prognostic promoter hypermethylation candidate biomarkers for PC (Haldrup et al., 2013). The gene discussed is HAPLN3; the disease is pachyonychia congenita.