Regular newborn screening enables detection of severe disorders in their asymptomatic early phase and thus allows the start of early treatment and prevention of long-term sequelae. This concept is in full accordance with care for so called rare diseases. Recently, the national NBS in Europe are under the supervision of ISNS and EUNENBS to ensure the quality control and unified approach. NBS in Slovak Republic has been provided for the whole population as a governmentally guaranteed activity since 1985. The first screened disorder was congenital hypothyroidism (CH). Patients have been screened for phenylketonuria (PKU) since 1995, for congenital adrenal hyperplasia (CAH) since 2003, and for cystic fibrosis (CF) since 2009. The organizational network of NBS ensures more than 98% coverage of the population of newborns. Between 1985 and 2011, the newborn screening centre (NSC SK) examined 3,239 068 newborn infants and confirmed 413 cases of CH (1: 4 128), 157 cases of PKU (1:5 908), 51 cases of CAH (1:8 677) and 26 CF cases (1:6 315). In 2012, the expanded NBS (ENBS) was introduced. It used tandem mass spectrometry (ms/ms) to detect other nine hereditary metabolic disorders (HMDs), defect of beta-oxidation of fatty acids, carnitine disorders, and organic acidurias. Four month pilot study revealed 12 positive cases in 25 000 screened newborns as well as other HMDs not included in the screening - in “peripheral view” of ms/ms. Since 1. January, ENBS has been performed as a regular NBS in the whole population. In January, fifteen new cases were detected (prevalence even 1:763).
A one-and-a-half year experience with expanded newborn screening (ENBS) in Slovakia provided by means of tandem mass spectrometry (LC-MS/MS) is presented.
Method ENBS was realised from dry blood samples of the regular NBS in National Screening Centre SK. The LC-MS/MS software used allowed evaluating even 73 analytes in MRM mode after cut-of limits in 99 percentile of daily values. The regular ENBS was oriented to 10 inherited metabolic disorders (IMDs), organic acids and carnitine defects (PKU/HPA, MSUD, GAI, IVA, MCAD, LCHAD, SCAD, CPT I, CPT II, CACT). Except these, many other variations of results were registered in perimeter of the method. They were individually evaluated until the confrmation or exclusion of the suspected diagnosis.
Results During the one-and-a-half years, 82 892 newborns were evaluated by ENBS and 34 positive cases of IMDs were detected and confrmed, which represents a screening prevalence of 1:2438 newborns. Out of these, 24 cases were from regular ENBS (PKU/HPA, MSUD, MCAD) with an incidence of 1:3 454, and 10 additional cases at the periphery of LC-MS/MS evaluation with a prevalence of 1:8 286.
Conclusion Preliminary experience and results with ENBS confrmed its high efectiveness not only in 10 IMDs included in regular ENBS, but also at perimeter of LC-MS/MS method, in which it is possible to detect additional IMDs not included in regular spectrum of ENBS. This group comprised 29% of all cases. In general, the prevalence is comparable with PKU and/or CAH.