Optimizing diagnosis and management of patients with ENPP1 deficiency: an expert opinion

Purpose: Ectonucleotide pyrophosphate/phosphodiesterase family member 1 (ENPP1) deficiency is a rare genetic disorder caused by loss-of-function ENPP1 gene mutations. Characterized by abnormally low circulating inorganic pyrophosphate concentrations, bone hypomineralization, soft tissue calcification, and arterial stenosis, ENPP1 deficiency is associated with a phenotypic spectrum that includes generalized arterial calcification of infancy type 1 (GACI1) and autosomal recessive hypophosphatemic rickets type 2 (ARHR2). Despite phenotypic differences, patients with GACI1 and ARHR2 have a marked, lifelong physical and emotional burden, with a negative impact on quality of life. Methods: A scientific board, comprising seven specialist physicians (endocrinologists, nephrologists, and pediatricians) practicing in Italy, held two virtual meetings to exchange knowledge regarding real-world clinical experience of GACI1 and ARHR2 using case examples, and to discuss strategies on how to increase disease awareness and optimize the diagnosis and management of these patients. Results: Five real-world clinical cases are described. The specialist physicians also provide guidance for optimizing the management pathway for patients with ENPP1 deficiency. Early identification of the clinical signs of disease, in combination with comprehensive diagnostic and follow-up testing, is essential for effective patient management. Conclusion: Early and accurate identification of ENPP1 deficiency by healthcare providers and comprehensive diagnostic testing is essential for the effective management of patients with GACI1 and ARHR2. Consistent follow-up is key to preventing complications and adverse outcomes. Although treatment options are limited, novel therapies are currently under clinical development.