Neonatal onset Citrullinemia type 2
OMIM number: 605814
Comments closing date: 10/04/2026
Neonatal onset 'Citrullinemia type 2', is a rare genetic condition caused by deficiency of Citrin which develops in the neonatal or infantile period, usually within the first days to weeks of life. Citrin is a protein needed for a process in the body called the urea cycle which helps remove ammonia from the body. Ammonia is produced when the body breaks down proteins. In neonatal citrullinaemia type II the body is unable to remove ammonia properly. Citrin is also important in the function of the liver and helps the body break down carbohydrates to make energy. In neonatal citrullinaemia type II citrin is missing or is not made correctly. We know that if there is not enough working citrin protein, the urea cycle in their body does not work well and ammonia builds up to high levels (hyperammonaemia) which is toxic to the body. It can result in jaundice, failure to thrive, enlargement of the liver, low protein levels and ultimately liver failure. Liver transplantation may be required in those with a severe presentation and if untreated the outcome can be very poor even with treatment there may be significant effects
