STABLE-ISOTOPE DILUTION ANALYSIS OF D-2-HYDROXYGLUTARIC AND L-2-HYDROXYGLUTARIC ACID - APPLICATION TO THE DETECTION AND PRENATAL-DIAGNOSIS OF D-2-HYDROXYGLUTARIC AND L-2-HYDROXYGLUTARIC ACIDEMIAS

A stable-isotope dilution assay has been developed for quantitation of D- and L-2-hydroxyglutaric acids in physiologic fluids. D- and L-2-hy droxyglutaric acids are separated as the 0-acetyl-di-(D)-2-butyl ester s. The method uses D,L-13,3,4,4-H-2(4)]-2-hydroxyglutaric acid as inte rnal standard with ammonia chemical ionization, selected ion monitorin g gas chromatography-mass spectrometry. For 13 patients with L-2-hydro xyglutaric aciduria, the concentrations of L-2-hydroxyglutaric acid we re urine, 1283 +/- 676 mmol/mol creatinine (range, 332-2742; n = 12 pa tients); plasma, 47 +/- 13 mumol/L (range, 27-62; n = 8); cerebrospina l fluid, 62 +/- 30 mumol/L (range, 34-100; n = 6). In a child with D-2 -hydroxyglutaric aciduria, the levels of D-2-hydroxyglutaric acid were urine, 1565 +/-847 mmol/mol creatinine (range, 729-2668; n = 4); plas ma, 61 +/- 14 mumol/L (range, 46-73; n = 3); cerebrospinal fluid, 15 a nd 25 mumol/L (n = 2). Control concentrations of D- and L-2-hydroxyglu taric acids were (D:L): urine (n = 18), 6.0 +/- 3.6 mmol/mol creatinin e (range, 2.8-17): 6.0 +/- 5.4 (range, 1.3-19); plasma (n = 10), 0.7 /- 0.2 mumol/L (range, 0.3-0.9): 0.6 +/- 0.2 (range, 0.5-1.0); cerebro spinal fluid (n = 10), 0.1 +/- 0.1 mumol/L (range, 0.07-0.3): 0.7 +/- 0.6 (range, 0.3-2.3). Investigation of control amniotic fluid (n = 10) revealed the following values (D:L): 1.2 +/- 0.4 mumol/L (range, 0.6- 1.8): 4.0 +/- 0.7 (range, 3.1-5.2), suggesting the feasibility of pren atal diagnosis in families at risk.