Estimation of ENPP1 deficiency genetic prevalence using a comprehensive literature review and population databases

Abstract

Abstract Background ENPP1 Deficiency—caused by biallelic variants in ENPP1—leads to widespread arterial calcification in early life (Generalized Arterial Calcification of Infancy, GACI) or hypophosphatemic rickets in later life (Autosomal Recessive Hypophosphatemic Rickets type 2, ARHR2). A prior study using the Exome Aggregation Consortium (ExAC)—a database of exomes obtained from approximately 60,000 individuals—estimated the genetic prevalence at approximately 1 in 200,000 pregnancies. Methods We estimated the genetic prevalence of ENPP1 Deficiency by evaluating allele frequencies from a population database, assuming Hardy–Weinberg equilibrium. This estimate benefitted from a comprehensive literature review using Mastermind ( https://mastermind.genomenon.com/ ), which uncovered additional variants and supporting evidence, a larger population database with approximately 140,000 individuals, and improved interpretation of variants as per current clinical guidelines. Results We estimate a genetic prevalence of approximately 1 in 64,000 pregnancies, thus more than tripling the prior estimate. In addition, the carrier frequency of ENPP1 variants was found to be highest in East Asian populations, albeit based on a small sample. Conclusion These results indicate that a significant number of patients with ENPP1 Deficiency remain undiagnosed. Efforts to increase disease awareness as well as expand genetic testing, particularly in non-European populations are warranted, especially now that clinical trials for enzyme replacement therapy, which proved successful in animal models, are underway.

Keywords

• ENPP1 deficiency
• Generalized arterial calcification of infancy (GACI)
• Autosomal recessive hypophosphatemic rickets type 2 (ARHR2)
• Population database
• Prevalence