Enzyme assay for diagnosis of guanidinoacetate methyltransferase deficiency.
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Cells, Cultured↗
Biomedical subjects
Nanda M Verhoeven
Publications and source records attributed to Nanda M Verhoeven.
Lack of creatine in muscle and brain in an adult with GAMT deficiency.
Guanidinoacetate methyltransferase deficiency, which so far has been exclusively detected in children, was diagnosed in a 26-year-old man. The full-blown spectrum of clinical symptoms already had been present since infancy without progression of symptoms during adolescence. Cranial magnetic resonance imaging showed normal findings. Ophthalmological examination showed no retinal changes. Besides creatine deficiency in the brain, a distinct lack of phosphocreatine in skeletal muscle was proved by (31)P magnetic resonance spectroscopy. Creatine substitution combined with a guanidinoacetate-lowering diet introduced first at the age of 26 years was shown to be effective by an impressive improvement of epileptic seizures, mental capabilities, and general behavior and by normalization of the (31)P spectrum in the skeletal muscle.
Adult↗
Diagnostic enzyme assay that uses stable-isotope-labeled substrates to detect L-arginine:glycine amidinotransferase deficiency.
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Amidinotransferases↗
Disease-related metabolites in culture medium of fibroblasts from patients with D-2-hydroxyglutaric aciduria, L-2-hydroxyglutaric aciduria, and combined D/L-2-hydroxyglutaric aciduria.
BACKGROUND: D-2-Hydroxyglutaric aciduria (D-2-HGA), L-2-hydroxyglutaric aciduria (L-2-HGA), and the combined D/L-2-hydroxyglutaric aciduria (D/L-2-HGA) are poorly understood organic acidurias. To investigate the usefulness of cultured human skin fibroblasts for both diagnostic and research purposes, we measured disease-related metabolites in the cell culture medium. METHODS: We measured D-2-hydroxyglutarate (D-2-HG), L-2-hydroxyglutarate (L-2-HG), succinate, 2-ketoglutarate, and citrate in fibroblast cell medium by stable-isotope-dilution gas chromatography-mass spectrometry and glutamine, glutamic acid, and lysine with an amino acid analyzer. We used six cell lines from patients with D-2-HGA, two from patients with L-2-HGA, three from patients with D/L-2-HGA, and seven control cell lines. Culture medium was analyzed after a 96-h incubation period. RESULTS: Culture media from cell lines from D-2-HGA patients contained D-2-HG at concentrations 5- to 30-fold higher than media from controls, whereas the concentration of L-2-HG in media was not increased. Media from L-2-HGA cell lines showed a fivefold increase in L-2-HG compared with controls. Media containing fibroblasts from D/L-2-HGA patients contained moderately increased amounts of both D-2-HG and L-2-HG. For all cell lines, succinate concentrations in the blank medium were higher than after 96 h of incubation with the exception of two of three D/L-2-HGA cell lines. Media of D-2-HGA cell lines had 2-ketoglutarate concentrations that were 40% of that for controls. Glutamic acid concentrations in media of these cell lines were 60% lower than in controls. CONCLUSIONS: Cell culture media from fibroblasts from patients with D-2-HGA, L-2-HGA, or D/L-2-HGA contain increased amounts the corresponding 2-HGs, demonstrating the suitability of fibroblasts for both diagnosis of and research concerning 2-HGAs.
Biomarkers↗
Profiling of pentose phosphate pathway intermediates in blood spots by tandem mass spectrometry: application to transaldolase deficiency.
BACKGROUND: Recently, several patients with abnormal polyol profiles in body fluids have been reported, but the origins of these polyols are unknown. We hypothesized that they are derived from sugar phosphate intermediates of the pentose phosphate pathway (PPP), and we developed a semiquantitative method for profiling of pentose phosphate pathway intermediates. METHODS: Sugar phosphates in blood spots were simultaneously analyzed by liquid chromatography-tandem mass spectrometry using an ion-pair-loaded C(18) HPLC column. The tandem mass spectrometer was operated in the multiple-reaction monitoring mode. Enzymatically prepared D-[(13)C(6)]glucose 6-phosphate was used as internal standard. The method was used to study sugar phosphates abnormalities in a patient affected with a deficiency of transaldolase (TALDO1; EC 2.2.1.2). RESULTS: In control blood spots, dihydroxyacetone phosphate, pentulose 5-phosphates, pentose 5-phosphates, hexose 6-phosphates, and sedoheptulose 7-phosphate were detected. Detection limits ranged from approximately 100 to approximately 500 nmol/L. Glyceraldehyde 3-phosphate and erythrose 4-phosphate were undetectable. Intra- and interassay imprecision (CVs) were 10-17% and 12-21%, respectively. In blood from the TALDO1-deficient patient, sedoheptulose 7-phosphate was increased. CONCLUSIONS: The new method allows investigation of patients in whom a defect in the PPP is suspected. Measurements of sugar phosphate intermediates of the PPP may provide new insights into metabolic defects underlying the accumulating polyols.
Adolescent↗
L-2-Hydroxyglutaric aciduria in Staffordshire Bull Terriers.
L-2-Hydroxyglutaric aciduria is an inborn error of metabolism, which has been recognized in humans since 1980. The metabolic defect responsible for the disease is unknown, but the disorder can be diagnosed in humans by elevations of the organic acid, L-2-hydroxyglutaric acid in the cerebrospinal fluid (CSF), plasma, and urine of affected patients. The disorder produces a variety of clinical neurological defects in humans including psychomotor retardation, seizures, and ataxia. There have previously been no recognized animal models of the disease. However, 6 Staffordshire Bull Terriers were recently identified with the disorder. The animals presented with a variety of clinical signs, most notably seizures, ataxia, dementia, and tremors. They were all screened for organic acid abnormalities in urine, and CSF and plasma (when available). Levels of L-2-hydroxyglutaric acid were elevated in all body fluids evaluated. The clinical, clinicopathologic, and magnetic resonance imaging (MRI) characteristics associated with L-2-hydroxyglutaric acid in Stafforshire Bull Terriers is reported herein and represents the first veterinary model of this inborn error of metabolism.
Animals↗