All four CpG sites (cg06480736, cg19774478, cg19788741 and cg22149516) on the SLCO4C1 promotor were significantly associated with BCR, and high methylation levels at the SLCO4C1 promotor predicted poor outcomes for PC by Kaplan-Meier analysis. The gene discussed is BCR; the disease is pachyonychia congenita.