Diagnosing lysosomal storage diseases in a Brazilian non-newborn population by tandem mass spectrometry

Abstract

OBJECTIVES:High-throughput mass spectrometry methods have been developed to screen newborns for lysosomal storage disorders, allowing the implementation of newborn screening pilot studies in North America and Europe. It is currently feasible to diagnose Pompe, Fabry, Gaucher, Krabbe, and Niemann-Pick A/B diseases, as well as mucopolysaccharidosis I, by tandem mass spectrometry in dried blood spots, which offers considerable technical advantages compared with standard methodologies. We aimed to investigate whether the mass spectrometry methodology for lysosomal storage disease screening, originally developed for newborns, can also discriminate between affected patients and controls of various ages.METHODS:A total of 205 control individuals were grouped according to age and subjected to mass spectrometry quantification of lysosomal α-glucosidase, β-glucocerebrosidase, α-galactosidase, acid sphingomyelinase, galactocerebrosidase, and α−L-iduronidase activities. Additionally, 13 affected patients were analyzed.RESULTS:The median activities for each enzyme and each age group were determined. Enzyme activities were significantly lower in individuals aged older than 18 years compared with those in newborns. Affected patients presented enzymatic activities corresponding to less than 20% of the age-matched controls.CONCLUSIONS:Our data indicate that the mass spectrometry methodology can be used for the screening of lysosomal storage diseases in non-newborn patients. However, for some diseases, such as Fabry and mucopolysaccharidosis I, a combination of biochemical and clinical data may be necessary to achieve accurate diagnoses.

Validation of a Multiplex Tandem Mass Spectrometry Method for the Detection of Selected Lysosomal Storage Diseases in Dried Blood Spots

“…Although the number of normal samples analyzed in this work is small, our preliminary results showed that the median activities of these 6 enzymes for newborns and nonnewborn controls were comparable to those reported in the literature 22,23 and the assays enabled unambiguous differentiation between samples obtained from healthy individuals and patients, suggesting that the method was effective in detecting Pompe, Fabry, Gaucher, Niemann-Pick A/B, MPS-I, and Krabbe diseases. Corroborating with findings published by Brand et al, 24 our results also demonstrated that some lysosomal enzymes present a higher activity in newborns when compared to older individuals.…”

Contribution of tandem mass spectrometry to the diagnosis of lysosomal storage disorders

“…DBS sample is very useful for LSD screening/diagnosis in countries with few metabolic laboratories (Brand et al 2013); this type of sample can be easily collected and shipped. Sampling temperature and storage conditions are important, since enzyme activities in DBS are highly sensitive to heat and humidity (Elbin et al 2011).…”

International working group identifies need for newborn screening for mucopolysaccharidosis type I but states that existing hurdles must be overcome

“…A complete diagnostic evaluation for MPS I should include referring the patient to a metabolic specialist and geneticist, and performing a combination of tests. These include quantitative and qualitative urinary glycosaminoglycan assessments, enzyme assays to evaluate α ‐L‐iduronidase activity and genetic and molecular testing to determine disease severity and the appropriate treatment approach . Testing enzyme activity and genotype using the dried blood spot test provides a valuable fast approach to the diagnosis of MPS I , but the results must always be confirmed by traditional laboratory methods.…”

“…Pilot newborn screening projects for lysosomal storage disorders have been implemented for Fabry disease, Pompe disease, Gaucher disease and Niemann–Pick diseases type A and B . Moreover, newborn screening programmes that include MPS I have been piloted in Taiwan , the United States – namely Missouri , Illinois and Washington State – Brazil and some regions of Italy . All of these studies used dried blood spot sampling and α ‐L‐iduronidase enzyme assays, although there were differences in the methodological strategies employed, with mass spectrometry , fluorometry and digital microfluid methods being used.…”