ABCC6 and autosomal recessive inherited pseudoxanthoma elasticum: Non-disease-causing polymorphisms have been identified; interestingly, an individual who was homozygous for an ABCC6 p.Arg1268Gln polymorphism did not have symptoms of PXE, and the Gln1268 (Q1268) allele had a frequency of 0.19 in healthy controls [50].