Quantitative Trait Locus and Integrative Genomics Revealed Candidate Modifier Genes for Ectopic Mineralization in Mouse Models of Pseudoxanthoma Elasticum

Abstract Pseudoxanthoma elasticum (PXE), a prototype of heritable multi-system ectopic mineralization disorders, is caused by mutations in the ABCC6 gene encoding a putative efflux transporter, ABCC6. The phenotypic spectrum of PXE varies, and the correlation between genotype and phenotype has not been established. To identify genetic modifiers, we performed quantitative trait locus analysis in inbred mouse strains that carry the same hypomorphic allele in Abcc6 yet with highly variable ectopic mineralization phenotypes of PXE. Abcc6 was confirmed as a major determinant for ectopic mineralization in multiple tissues. Integrative analysis using functional genomics tools that included GeneWeaver, String, and Mouse Genome Informatics identified a total of nine additional candidate modifier genes that could influence the organ-specific ectopic mineralization phenotypes. Integration of the candidate genes into the existing ectopic mineralization gene network expands the current knowledge on the complexity of the network that as a whole governs ectopic mineralization in soft connective tissues.