Nutrition support for glutaric acidemia type I.

Glutaric acidemia type I is a rare, autosomal recessive, inborn error of lysine and tryptophan metabolism. This disorder is caused by a defect in the mitochondrial enzyme glutaryl-coenzyme A dehydrogenase, resulting in permanent or episodic elevations of glutaric acid. Despite clinical variability, untreated children often experience progressive neurologic damage that frequently leads to death. Recent evidence suggests that a lysine- and tryptophan-restricted diet and pharmacologic therapy with oral riboflavin and L-carnitine may arrest the neurologic deterioration. Several cases of normal growth and development have been reported in children diagnosed and treated before neurologic insult. In this article, we review previously published experience with dietary and pharmacologic therapy and provide guidelines for nutrition support based on our experience of treating four affected children. We suggest that dietary restriction of lysine and tryptophan is a safe and potentially effective therapy for individuals with glutaric acidemia type I.