[SP6-3D-5] Diagnosis and treatment of two Chinese boys with Hyperornithinemia-Hyperammonemia-Homocitrullinuria syndrome
[Objective] Hyperornithinemia-Hyperammonemia-Homocitrullinuria (HHH) Syndrome is a very rare disease of urea cycle defects. In this study, two Chinese cases with progressive encephalopathy and liver dysfunction had been experienced. [Methods] Two boys came from unrelated Chinese families. They were hospitalized because of developmental delay, liver damage and hyperammonemia. HHH syndrome was confirmed by the biochemical and gene testing. [Results] Both of the two boys disliked protein-rich foods from the infant period. Decreased blood arginine and elevated urinary orotic acid and uracil were noticed in the two boys. Cranial MRI showed basal ganglia region. In Case 1, a novel homozygous missense mutation c.416A>G (p.E139G) was identified from the SLC25A15 gene. In Case 2, a known pathogenic homozygous nonsense mutation c.535C>T (p.R179X) was found. Liver transplantation had been performed successfully for Case 1 at the age of 6 years. Rapidly clinical and biochemical improvement were observed after liver transplantation. Case 2 is treated by protein-restricted diet with the supplement of arginine, L-carnitine and other nutrients. [Conclusions] HHH syndrome is a rare autosomal recessive disorder caused by impaired ornithine transport due to mutations in SLC25A15 gene. Till now, 111 patients were reported worldwide. Only a Belgian patient underwent liver transplantation. In this study, two Chinese cases of HHH syndrome were firstly reported in Mainland China. Liver transplantation had been performed successfully for one Case.