Results of liver cell transplantation in urea cycle disorders

The urea cycle is the final pathway for the metabo- lism of waste nitrogen in humans. As many inborn errors of metabolism, urea cycle disorders are based in the liver, but do not damage the liver itself. Indeed, an anomaly of this pathway leads to an accumulation of ammonia, with several deleterious effects to the brain including neurological damage and cognitive deficits. Management by strict diet protein restriction and use of ammonium scavengers are not always sufficient to con- trol the disease and, eventually, the liver remains the tar- get of curative treatment. Orthotopic liver transplanta- tion (OLT) becomes then the ultimate solution to avoid repeated encephalopathic episodes and irreversible brain damage. Rapid transplantation is however limited by the organ shortage and the waiting time is long, during which irreversible brain damage may occur and jeopar- dize the long-term psychomotor development1 (2).