pyrophosphate and Hearing-Loss

This review summarizes current understanding of generalized arterial calcification of infancy (GACI), emphasizing pathophysiology, clinical presentation, and approaches and controversies in management.. Identification of causative ENPP1 mutations revealed that GACI arises from deficiencies in inorganic pyrophosphate (leading to calcifications) and adenosine monophosphate (leading to intimal proliferation). Identification of genotypic and phenotypic overlap with pseudoxanthoma elasticum and autosomal recessive hypophosphatemic rickets further advanced understanding of GACI as a complex, multisystemic disease. Clinical data is limited to small, retrospective samples; it is therefore unknown whether commonly used medications, such as bisphosphonates and hypophosphatemia treatment, are therapeutic or potentially harmful. ENPP1-Fc replacement represents a promising approach warranting further study. Knowledge gaps in natural history place clinicians at high risk of assigning causality to interventions that are correlated with changes in clinical status. There is thus a critical need for improved natural history studies to develop and test targeted therapies.

Topics: Adenosine Monophosphate; Bone Density Conservation Agents; Calcinosis; Cardiovascular Agents; Chelating Agents; Diphosphates; Diphosphonates; Familial Hypophosphatemic Rickets; Genotype; Hearing Loss; Humans; Multidrug Resistance-Associated Proteins; Phenotype; Phosphoric Diester Hydrolases; Pseudoxanthoma Elasticum; Pyrophosphatases; Thiosulfates; Tooth Diseases; Vascular Calcification; Vitamin D