Background: Adult-onset type II citrullinemia (CTLN2) is an autosomal recessivedisorder caused by mutations of SLC25A13 gene encoding citrin and is characterized by recurrent encephalopathywith hyperammonemia. Factors affecting disease progression remain unknown. We report a case with CTLN2,whose clinical course was rapidly worsened by the administration of Glyceol[sup]®[/sup], a hyperosmotic diureticsolution consisting of 10% glycerol and 5% fructose in saline. Case Report: A 34-year-old man was admittedin coma after repeated episodes of altered consciousness. His plasma ammonia level was markedly elevatedwithout any evidence of liver diseases. Brain MRI revealed high signal intensities at the bilateral cingulategyri and insular cortices, suggesting hepatic encephalopathy. We administered Glyceol[sup]®[/sup]. intravenouslyto alleviate brain edema, however, he developed intractable seizures along with steep increase in plasmaammonia levels (from 808 to 2210 microg/dL) and died. The diagnosis of CTLN2 was confirmed by elevationsof plasma citrulline level (384.3 nmol/mL; normal 17-43 nmol/mL) and serum pancreatic secretory trypsininhibitor (PSTI) (110 ng/mL; normal 4.6-12.2 ng/mL), decrease in hepatic argininosuccinate synthetaseactivity (5.5% of control), lack of hepatic citrin protein expression and mutations in SLC25A13 gene(compound heterozygote with S225X and Ex1-1G>A). Conclusions: Physicians should take CTLN2 into considerationas a differential diagnosis in Asian patients with a history of repeated unconsciousness with hyperammonemiaand use D-mannitol but not glycerol to treat brain edema in patients with CTLN2.

Keywords: Citrullinemia - therapy, Brain Edema - therapy, Diagnosis, Differential, Fatal Outcome, Fructose - administration & dosage, Glycerol - administration & dosage, Hypertonic Solutions - adverse effects, Membrane Transport Proteins - genetics, Mitochondrial Membrane Transport Proteins, Mitochondrial Proteins - genetics, Mutation