Mutations in ABCC6, a gene encoding for the ABC transporter protein 6 of subfamily C, formerly known as multidrug resistance-associated protein 6 (MRP6), are the cause of pseudoxanthoma elasticum (PXE; Kool et al., 1999; Bergen et al., 2000; Le Saux et al., 2000; Ringpfeil et al., 2000; Miksch et al., 2005; Schulz et al., 2006). This evidence concerns the gene ABCC6 and pseudoxanthoma elasticum (inherited or acquired).