IL1B and Pseudoxanthoma elasticum: Further prioritization based on these three processes led to four candidate modifier genes of the severity of the cardiovascular PXE phenotype: NLRP1, SELE, CSF1R, and TRPV1. Interestingly, these four genes share a common denominator as they can all signal through IL1B, a member of the IL1 family, which also consists of IL1alpha and IL1-ra, the latter being an endogenous IL1 inhibitor.