Cutaneous features of pseudoxanthoma elasticum in a patient with generalized arterial calcification of infancy due to a homozygous missense mutation in the ENPP1 gene

Background Pseudoxanthoma elasticum (PXE) manifests with cutaneous lesions consisting of yellowish papules coalescing into plaques of inelastic skin. Histopathology demonstrates accumulation of pleiomorphic elastic structures with progressive mineralization. The classic form of PXE is caused by mutations in the ABCC6 gene. Objectives A 2-year-old patient with PXE of the neck, inguinal folds and lower abdomen, and with extensive tissue mineralization, was evaluated for the underlying mutations in candidate genes known to be involved in ectopic mineralization disorders. Methods The patient's genotype was studied by sequencing ABCC6, MGP and ENPP1 genes, encoding proteins which harbour mutations in ectopic mineralization disorders. Results No pathogenetic mutations were found in the ABCC6 or MGP genes. Sequencing of ENPP1 disclosed a homozygous missense mutation, p.Y513C, associated with generalized arterial calcification of infancy. Conclusions This study demonstrates the presence of the cutaneous features of PXE in a genetically distinct disease, generalized arterial calcification of infancy, and thus expands the spectrum of PXE-related disorders.