Adult Reye's syndrome: a review with new evidence for a generalized defect in intramitochondrial enzyme processing.

A 42-year-old woman developed a flu-like illness and died 8 days later with Reye's syndrome (RS). There are 26 other cases of adult-onset RS reported. Biochemical, immunologic, and molecular studies of liver, brain, and skeletal muscle revealed a non-uniform decrease in several mitochondrial residual enzyme activities in liver and brain. Pyruvate carboxylase activity was negligible. Cross-reacting material was present in normal abundance in isolated liver mitochondria for several enzymes that had reduced catalytic activity including pyruvate carboxylase. Subunit II (encoded by mitochondrial DNA) and subunit IV (encoded by nuclear DNA) of cytochrome c oxidase also were present in normal abundance with normal electrophoretic mobility. These observations, combined with pertinent findings of other investigators, allow us to speculate that the intramitochondrial matrix chemical environment is disturbed by preceding pathophysiologic events resulting in a lowered ATP/ADP ratio. The lowered intramitochondrial energetic state interferes with the refolding and assembly of imported mitochondrial proteins, causing a loss of the catalytic efficiency of these enzymes. This explains the selective vulnerability of mitochondria in RS and the non-uniform, disproportionate loss of enzyme activity.