Whole exome sequencing identified three ABCC6 variants in two Pakistani families with pseudoxanthoma elasticum phenotype.

Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder of ectopic mineralization and fragmentation of elastic fibers in skin, eyes, cardiovascular and digestive system. PXE is caused by sequence variants in ABCC6, which encodes multidrug resistance-associated protein 6 (MRP6, also known as the ABCC6 protein). MRP6 is an important regulator of inorganic plasma pyrophosphate that acts as an inhibitor of ectopic mineralization observed in PXE patients with low inorganic plasma pyrophosphate levels.