Four years of expanded newborn screening in Portugal with tandem mass spectrometry

• DOI: 10.1007/s10545-010-9048-z
• Publication Date: 2010-02-22T08:39:37Z
• Authors: Laura Vilarinho; Hugo Rocha; Carmen Sousa; Ana Marcão; Helena Fonseca; Mário Bogas; Rui Vaz Osório
• Keywords: Time Factors; Portugal; Infant, Newborn; Prognosis; 3. Good health; 03 medical and health sciences; Early Diagnosis; Neonatal Screening; Phenotype; 0302 clinical medicine; Predictive Value of Tests; Tandem Mass Spectrometry; Carnitine; Prevalence; Humans; False Positive Reactions; Genetic Predisposition to Disease; Amino Acids; Biomarkers; Metabolism, Inborn Errors; Program Evaluation

AbstractIntroductionThe Portuguese Neonatal Screening Programme (PNSP) was started in 1979 for phenylketonuria (2,590,700 newborns screened; prevalence 1:11,031) and, shortly after, for congenital hypothyroidism (2,558,455 newborns screened; prevalence 1:3,174). In 2004, expanded neonatal screening was implemented in the National Laboratory. The programme is not mandatory and has 99.8% coverage of the country (including Madeira and the Azores islands).Material and methodsIn the past 4 years, 316,243 neonates were screened with the use of tandem mass spectrometry (MS/MS) to test for selected amino acids and acylcarnitines.ResultsDuring this time, 132 patients were identified with 24 different inherited metabolic diseases (classic forms and variants). To date, the global frequency for all disorders integrated into the PNSP is estimated to be 1:1,380, with 1:2,396 for metabolic disorders. A total of 379 tests (0.12%) were classified as having false positive results, yielding an overall specificity of 99.9%. Despite the low frequency of several disorders, the positive predictive value of the overall MS/MS screening was found to be 26%, reflecting high diagnostic specificity of the method. Diagnostic sensitivity of extended screening for the different groups of disorders was 100%. Eight cases of maternal disorders [three glutaric aciduria type I, one carnitine transporter defect, and four 3‐methylcrotonyl coenzyme A (CoA) carboxylase deficiency] were also detected through newborn screening.ConclusionsOur data support the advantage of a centralised laboratory for screening an elevated number of samples and making decisions if relying on a clinical network able to provide fast treatment and a good outcome in the screened cases.