Editor—Pseudoxanthoma elasticum (PXE, MIM 264800) is an inherited disorder of connective tissue in which the elastic fibres of the skin, eyes, and cardiovascular system slowly become calcified, causing a spectrum of disease involving these three organ systems, with highly variable phenotypic expression.1 2Mutations in the ABCC6 gene (previously known as MRP6), encoding a 1503 amino acid membrane transporter, have recently been identified by our group and others3-7 as the genetic defect responsible for PXE. We subsequently designed a strategy for a complete mutational analysis of the ABCC6 gene, in order to provide accurate molecular and prenatal diagnosis of PXE. During this mutational screening, we have found evidence for the existence of at least one pseudogene highly homologous to the 5′ end ofABCC6. Sequence variants in thisABCC6-like pseudogene could be mistaken for mutations in the ABCC6 gene and consequently lead to erroneous genotyping results in pedigrees affected with pseudoxanthoma elasticum.