title: Effect of temperature on lysosomal enzyme activity during preparation and storage of dried blood spots.
abstract: BACKGROUND
  The use of dried blood spots (DBS) for the assay of lysosomal enzymes has facilitated the implementation of pilot studies for newborn screening for lysosomal storage disorders in various developed countries. The aim of the study was to determine the influence of ambient temperature during DBS preparation and storage on lysosomal enzyme activity in a developing, tropical country.
  
  
  METHODS
  Blood samples from 12 healthy subjects collected on a S&S 903 filter paper were dried and stored at different temperatures for different periods of time. Activities of five lysosomal enzymes (acid α-glucosidase, acid α-galactosidase, acid β-glucocerebrosidase, acid sphingomyelinase, and galactocerebrosidase) were determined by tandem mass spectrometric and fluorimetric (acid α-glucosidase and acid β-glucocerebrosidase only) assays.
  
  
  RESULTS
  The mean activities of all five enzymes decreased significantly when DBS was dried at temperatures above 24°C (P<.0001). DBS stored at 4°C, 24°C, 30°C, 37°C, and 45°C for 10 days and more, also showed significant reduction in activities of all five enzymes (P<.0001).
  
  
  CONCLUSIONS
  The results highlight the importance of maintaining the correct ambient temperature during DBS preparation and storage to avoid false positive results when screening for lysosomal storage disorders.
authors.affiliation: Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
authors.forename: Manjunath
authors.initials: M
authors.lastname: Supriya
authors.affiliation: Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
authors.forename: Tanima
authors.initials: T
authors.lastname: De
authors.affiliation: Department of Neurochemistry, National Institute of Mental Health and Neuro Sciences, Bangalore, India.
authors.forename: Rita
authors.identifier: http://orcid.org/0000-0002-0024-4748
authors.initials: R
authors.lastname: Christopher
mesh_terms: D001800:Blood Specimen Collection / Q000379:methods / Q000592:standards; D059788:Dried Blood Spot Testing / Q000379:methods / Q000592:standards; D004795:Enzyme Stability; D005470:Fluorometry; D006026:Glycoside Hydrolases / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008247:Lysosomes / Q000201:enzymology*; D053719:Tandem Mass Spectrometry; D013696:Temperature
chemical_list: D006026:Glycoside Hydrolases
keywords: ambient temperature; dried blood spot; fluorimetry; lysosomal enzymes; tandem mass spectrometry