3-Hydroxy-3-methylglutaryl-coenzyme A lyase deficiency (HMGCLD) is a rare autosomal recessively inherited metabolic disorder. Patients suffer from avoidable neurologically devastating metabolic decompensations and thus would benefit from newborn screening (NBS). The diagnosis is currently made by measuring dry blood spot acylcarnitines (C5OH and C6DC) followed by urinary organic acid profiling for the differential diagnosis from several other disorders. Using untargeted metabolomics (reversed-phase UHPLC coupled to an Orbitrap Elite hybrid mass spectrometer) of plasma samples from 5 HMGCLD patients and 19 age-matched controls, we found 3-methylglutaconic acid and 3-hydroxy-3-methylglutaric acid, together with 3-hydroxyisovalerylcarnitine as the most discriminating metabolites between the groups. In order to evaluate the NBS potential of these metabolites we quantified the most discriminating metabolites from untargeted metabolomics in 23 blood spots from 4 HMGCLD patients and 55 controls by UHPLC tandem mass spectrometry. The results provide a tool for expanded NBS of HMGCLD using tandem mass spectrometry. Selected reaction monitoring transition 262/85 could be used in a first-tier NBS analysis to screen for elevated 3-hydroxyisovalerylcarnitine. In a positive case, a second-tier analysis of 3-hydroxy-3-methylglutaric acid and 3-methylglutaconic acid in a dry blood spot using UHPLC tandem mass spectrometry instruments confirms the diagnosis. In conclusion, we describe the identification of new diagnostic biomarkers for HMGCLD and their application in NBS in dry blood spots. By using second-tier testing, all patients with HMGCLD were unequivocally and correctly diagnosed.
- Publikační typ
- časopisecké články MeSH
Mucopolysaccharidoses (MPS) are severe, inherited metabolic disorders caused by storage of glycosaminoglycans (GAGs). Sanfilippo disease (mucopolysaccharidosis type III, MPS III) is described as severe neurological type of MPS, characterized by rapid deterioration of brain functions. No therapy for Sanfilippo disease is approved to date, however, a specific substrate reduction therapy (SRT), called gene expression-targeted isoflavone therapy (GET IT), has been used as an experimental therapy. In this report, we describe effects of treatment of six Sanfilippo disease patients with GET IT, in which the dose of genistein (5,7-dihydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one), an active compound of GET IT present in the soy isoflavone extract, has been increased to 10, and then to 15 mg/kg/day, contrary to the previously reported dose of 5 mg/kg/day. By measuring levels of urinary GAGs and assessing hair dysmorphology as biomarkers, and by considering clinical symptoms of patients, we obtained results suggesting that elevated doses of genistein may improve efficacy of GET IT for Sanfilippo disease.
- Publikační typ
- časopisecké články MeSH
