Functional Assessment of Missense Variants in the ABCC6 Gene Implicated in Pseudoxanthoma Elasticum, a Heritable Ectopic Mineralization Disorder.

Pseudoxanthoma elasticum, a heritable multisystem ectopic mineralization disorder, is caused by inactivating mutations in the ABCC6 gene. The encoded protein, ABCC6, a transmembrane transporter, has a specialized efflux function in hepatocytes by contributing to plasma levels of inorganic pyrophosphate, a potent inhibitor of mineralization in soft connective tissues. Reduced plasma inorganic pyrophosphate levels underlie the ectopic mineralization in pseudoxanthoma elasticum. In this study, we characterized the pathogenicity of three human ABCC6 missense variants using an adenovirus-mediated liver-specific ABCC6 transgene expression system in an Abcc6