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Development and implementation of a novel assay for l ‐2‐hydroxyglutarate dehydrogenase ( l ‐2‐HGDH) in cell lysates: l ‐2‐HGDH deficiency in 15 patients with l ‐2‐hydroxyglutaric aciduria
Author(s) -
Kranendijk M.,
Salomons G. S.,
Gibson K. M.,
AktugluZeybek C.,
Bekri S.,
Christensen E.,
Clarke J.,
Hahn A.,
Korman S. H.,
MejaskiBosnjak V.,
SupertiFurga A.,
VianeySaban C.,
Knaap M. S.,
Jakobs C.,
Struys E. A.
Publication year - 2009
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/s10545-009-1282-x
Subject(s) - lymphoblast , dehydrogenase , enzyme , microbiology and biotechnology , biochemistry , glutamate dehydrogenase , biology , cell culture , chemistry , glutamate receptor , genetics , receptor
Summary l ‐2‐hydroxyglutaric aciduria ( l ‐2‐HGA) is a rare inherited autosomal recessive neurometabolic disorder caused by mutations in the gene encoding l ‐2‐hydroxyglutarate dehydrogenase. An assay to evaluate l ‐2‐hydroxyglutarate dehydrogenase ( l ‐2‐HGDH) activity in fibroblast, lymphoblast and/or lymphocyte lysates has hitherto been unavailable. We developed an l ‐2‐HGDH enzyme assay in cell lysates based on the conversion of stable‐isotope‐labelled l ‐2‐hydroxyglutarate to 2‐ketoglutarate, which is converted into l ‐glutamate in situ. The formation of stable isotope labelled l ‐glutamate is therefore a direct measure of l ‐2‐HGDH activity, and this product is detected by liquid chromatography‐tandem mass spectrometry. A deficiency of l ‐2‐HGDH activity was detected in cell lysates from 15 out of 15 l ‐2‐HGA patients. Therefore, this specific assay confirmed the diagnosis unambiguously affirming the relationship between molecular and biochemical observations. Residual activity was detected in cells derived from one l ‐2‐HGA patient. The l ‐2‐HGDH assay will be valuable for examining in vitro riboflavin/FAD therapy to rescue l ‐2‐HGDH activity.