Late-onset form of β-electron transfer flavoprotein deficiency

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Multiple acyl-CoA-dehydrogenase deficiency (MADD) or glutaric aciduria type II (GAII) are a group of metabolic disorders due to deficiency of either electron transfer flavoprotein (ETF) or electron transfer flavoprotein ubiquinone oxidoreductase (ETF-QO). We report the clinical features and biochemical and molecular genetic analyses of a patient with a mild late-onset form of GAII due to β-ETF deficiency. Biochemical data showed an abnormal urine organic acid profile, low levels of free carnitine, increased levels of C 10:1 n−6 , and C 14:1 n–9 in plasma, and decreased oxidation of [9,10- 3 H ]palmitate and [9,10- 3 H ]myristate in fibroblasts, suggesting MAD deficiency. In agreement with these findings, mutational analysis of the ETF/ETFDH genes demonstrated an ETFB missense mutation 124T>C in exon 2 leading to replacement of cysteine-42 with arginine (C42R), and a 604_606AAG deletion in exon 6 in the ETFB gene resulting in the deletion of lysine-202 (K202del). The present report delineates further the phenotype of mild β-ETF deficiency and illustrates that the differential diagnosis of GAII is readily achieved by mutational analysis.