Biochemical and clinical studies of a new case of alpha-aminoadipic aciduria

A mentally retarded, 10-year-old female with obesity, hypotonia, clumsiness and mild ocular abnormalities excreted in her urine large amounts of alpha-aminoadipic acid. Amino acid analyser studies and gas-liquid chromatography--mass spectrometry (GC--MS) confirmed the presence of alpha-aminoadipic acid in both urine and plasma but, in contrast to most other patients with this disorder, failed to demonstrate significant levels of alpha-ketoadipic acid in urine. Other known causes of alpha-aminoadipic aciduria were eliminated by showing that levels of lysine, saccharopine and pipecolic acid in plasma and urine were normal and that the activity of glutaryl-CoA dehydrogenase was also normal. Loading with L-lysine and L-tryptophan both increased the concentration of alpha-aminoadipic acid in blood and urine compatible with the primary deficiency of alpha-ketoadipate dehydrogenase, in spite of the absence of alpha-ketoadipic aciduria. Dietary restriction of lysine and administration of vitamins B1 and B6 were unsuccessful in correcting the biochemical abnormality.