CSF1R and Pseudoxanthoma elasticum: Using whole exome sequencing of extreme phenotypes and mixture of effects analyses, SKAT-O and C-alpha, a panel of 86 novel candidate modifier genes were identified, among which four candidate genes, i.e., NLRP1, SELE, CSF1R, and TRPV1, could be prioritized for the cardiovascular phenotype of PXE.