Newborn screening for hyperphenylalanine
Institute of Medical genetics of Hospital Italiano
Keywords:
PHENYLKETONURIA, PHENYLALANINE, FLUOROMETRYAbstract
Newborn detection of metabolic congenital abnormalities by newborn screening consists of systematic searching of affections that could be treated in early stages. Since November 1993, quantification of phenylalanine was obtained by filter paper blood spots collected from newborns by fluorometric technique for hyperphenylalanine. Reagents were prepared in the laboratory, accuracy of the method was controlled by an external quality control program (reference method).
Cutoff for the population (n=190) was 2.5 mg/dl of phe-nylalanine. The fluorometric technique used was assessed. Regression analysis for the results obtained by fluorometric technique and the reference method showed lineal association among those techniques (n=93; r=0.94; y=0.87x + 0.519) and reliance on the proposed technique based on the equivalence of the techniques. Phe stability was analysed using filter paper blood spots storaged at 4°C. Amino acid profiles retrieved after five years of storage (83% to 100%) and the statistic test used showed that the amino acid is stable when storaged under these conditions.
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