Expanded Newborn Screening for Inherited Metabolic Diseases

Abstract

Expanded newborn screening in Sicily began as a pilot project in 2011, supported by the Sicilian Region in Eastern andWestern Sicily, with the aim of screening an estimated 50,000 newborns per year. Newborns are screened for fatty acid oxidation, organic acid, urea cycle and amino acid disorders. Blood collection is performed between 48 and 72 h of life, and dried blood spots are sent by courier to laboratory. Analyte measurement are extracted fromdried blood spots with a solution containing stable-isotope labeled internal standard and analyzed by tandem mass spectrometry. In Eastern Sicily (Catania city and surroundings) during the pilot project, cut-off values for all analytes were established after evaluation of 5000 healthy newborns. Up to now, blood spots from up to 19100 infants have been analyzed and 35 recalls have been made with 9 affected patients identified (maternal Methylcrotonyl-CoA carboxylase, Phenylketonuria, Hyperphenylalaninemia, Hypermetioninemie, Methylmalonic aciduria with homocystinuria, Citrullinemie I). Screening results show sensitivity: 100%; specificity: 99,9%; predictive positive value: 25,7%; and predictive negative value: 100%. Diagnosed newborns are currently followed at the regional referral center and laboratory of inherited metabolic disease. Continuance of expanded newborn screening in Sicily enhances prevention and care of IMD in south Mediterranean countries.