Studies on a case of HHH-syndrome (hyperammonemia, hyperornithinemia, homocitrullinuria)

Neuropediatrics. 1986 Feb;17(1):48-52. doi: 10.1055/s-2008-1052499.


A patient with the hyperornithinemia, hyperammonemia, homocitrullinuria syndrome is described. This patient represents the 12th documented case of this rare, presumably autosomal recessive condition. Increased levels of ammonia, ornithine and homocitrulline were demonstrated in blood and cerebrospinal fluid. The blood ammonia concentration could be lowered by supplementation of the diet with low doses of arginine. High doses of arginine precipitated seizures, although plasma levels of arginine and ornithine were not altered. The uptake of ornithine by the particulate fraction of the patient's fibroblasts was lower than that of controls, but still measurable. It is suggested that HHH patients have a partial impairment of the uptake of ornithine by mitochondria.

Publication types

  • Case Reports
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Metabolism, Inborn Errors / metabolism*
  • Amino Acids / metabolism*
  • Ammonia / metabolism*
  • Biological Transport
  • Child, Preschool
  • Citrulline / analogs & derivatives*
  • Citrulline / urine
  • Fibroblasts / metabolism
  • Follow-Up Studies
  • Humans
  • Kinetics
  • Male
  • Ornithine / metabolism*
  • Psychomotor Disorders / metabolism
  • Seizures / metabolism
  • Syndrome


  • Amino Acids
  • homocitrulline
  • Citrulline
  • Ammonia
  • Ornithine