While PXE is considered a PPi-deficiency syndrome due to decreased ABCC6-mediated efflux of ATP into the systemic circulation, resulting in decreased catalysis to PPi by the ENPP1 enzyme, future studies should investigate the contribution of decreased mitochondrial oxidative phosphorylation and therefore reduced ATP production to the PPi deficit. The gene discussed is ABCC6; the disease is Pseudoxanthoma elasticum.