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ENPP1 Deficiency is a genetic condition caused by loss-offunction mutations in the ENPP1 gene. Infants can manifest with ectopic arterial calcifications (Fig 1A), stenoses (Fig 1B) and cardiac complications, usually diagnosed as generalized arterial calcification of infancy (GACI). 1 Approximately 50% of infants with GACI do not survive the first 6 months of life. Paradoxically, children and adults with ENPP1 Deficiency often develop autosomal recessive hypophosphatemic rickets type 2 (ARHR2), due to inappropriately high FGF23 levels. 1, 2 The presentation of ENPP1 Deficiency rickets can mimic the femoral bowing and metaphyseal irregularities of other hypophosphatemic rickets (Fig 1C)