Triple H syndrome (hyperornithinemia, hyperammonemia, and homocitrullinuria) is a very rare autosomal recessive genetic disease due to defective transportation of ornithine into the mitochondria. Onset may be neonatal, infantile or juvenile (until adolescence). The initial clinical signs are coma due to hyperammonemia, convulsions, and hypotonia. The disease is Hyperornithinemia-hyperammonemia-homocitrullinuria (Orphanet_415). Also known as: HHH syndrome, Triple H syndrome.