Prenatal screening of sialic acid storage disease and confirmation in cultured fibroblasts by LC-MS/MS

Hans Bosch, Linda Oemardien, Gosia Srebniak, M Piraud, Jan Huijmans, Frans Verheijen, George Ruijter

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Sialic acid storage disease (SASD) is an inborn error resulting from defects in the lysosomal membrane protein sialin. The SASD phenotypical spectrum ranges from a severe presentation, infantile sialic acid storage disease (ISSD) which may present as hydrops fetalis, to a relatively mild form, Salla disease. Screening for SASD is performed by determination of free sialic acid (FSA) in urine or amniotic fluid supernatant (AFS). Subsequent diagnosis of SASD is performed by quantification of FSA in cultured fibroblasts and by mutation analysis of the sialin gene, SLC17A5. We describe simple quantitative procedures to determine FSA as well as conjugated sialic acid in AFS, and FSA in cultured fibroblasts, using isotope dilution ((13)C(3)-sialic acid) and multiple reaction monitoring LC-ESI-MS/MS. The whole procedure can be performed in 2-4 h. Reference values in AFS were 0-8.2 mu mol/L for 15-25 weeks of gestation and 3.2-12.0 mu mol/L for 26-38 weeks of gestation. In AFS samples from five fetuses affected with ISSD FSA was 23.9-58.9 mu mol/L demonstrating that this method is able to discriminate ISSD pregnancies from normal ones. The method was also validated for determination of FSA in fibroblast homogenates. FSA in SASD fibroblasts (ISSD; 20-154 nmol/mg protein, intermediate SASD; 12.9-15.1 nmol/mg, Salla disease; 5.9-7.4 nmol/mg) was clearly elevated compared to normal controls (0.3-2.2 nmol/mg). In conclusion, we report simple quantitative procedures to determine FSA in AFS and cultured fibroblasts improving both prenatal diagnostic efficacy for ISSD as well as confirmatory testing in cultured fibroblasts following initial screening in urine or AFS.
Original languageUndefined/Unknown
Pages (from-to)1069-1073
Number of pages5
JournalJournal of Inherited Metabolic Disease
Issue number5
Publication statusPublished - 2011

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