Many rare inherited metabolic disorders, for example fatty acid oxidation defects and urea cycle disorders, are now known to cause an illness similar to Reye's syndrome.
The early treatment of these "Reye-like illnesses" is similar to that of Reye's syndrome but some require special drugs or diets for treatment and to prevent recurrence of illness.
Special laboratory tests are required to make certain that such disorders are excluded in all children in whom a diagnosis of Reye's syndrome is considered.
Furthermore other children in the family may also have the genetic disorder in a latent form.
These disorders may also rarely manifest for the first time in teenagers or older adults.