CTLA4 and pachyonychia congenita: The additive gene models for COX2-765, HIF-1α rs11549467, and TP53 rs9895829, the recessive gene model for VDR rs2228570 and TP53 rs9895829, the recessive gene model for VDR rs2228570, as well as dominant gene models for VDR rs2228570, CTLA-4 rs231775 and MTHFR rs1801133 were the most optimal for determining PC susceptibility.