Citrullinemia is a rare inherited disorder caused by either a deficiency or absence of the enzyme argininosuccinate synthetase (ASS). There are three forms: an acute form that begins at birth, a later-onset form with milder symptoms, and an asymptomatic form.
ASS helps remove nitrogen from the body. Citrullinemia causes the accumulation of nitrogen in the form of ammonia in the body.
Common signs and symptoms of citrullinemia include:
With there being three different forms of citrullinemia, these symptoms can manifest immediately after birth or may manifest later, with children who have the milder type alternating between periods of feeling well and unwell. Any form of citrullinemia can put life at risk if left untreated.
Some pregnant women may display these same symptoms when the child they’re carrying has citrullinemia.
Citrullinemia is caused by a genetic mutation in the ASS1 gene that makes the ASS protein. It is inherited in an autosomal recessive pattern, meaning both parents need to pass abnormal copies of the ASS1 gene to their children for the child to get citrullinemia. If you have a family history of citrullinemia or other metabolic disorders and are considering having a family, you may consider genetic testing.
A family history of citrullinemia is the only risk factor.
Citrullinemia is often diagnosed at birth. However, a comprehensive family history, overview of symptoms, and blood tests can give your healthcare provider a clear idea of whether or not your child has citrullinemia. It’s recommended that siblings of a child with citrullinemia get tested to see if they carry the gene.
Complications of citrullinemia include liver failure, neurological delays, and coma.
Treatment requires a quick diagnosis and quick control of the high ammonia levels in the blood to prevent the brain from being affected. Medications can help remove excess nitrogen. Dietary restrictions and supplements can help reduce the amount of protein the body is required to metabolise while ensuring children still receive the nutrients they need to grow.
Aggressive treatment may sometimes be needed if there is too much ammonia in the blood. This may look like hospitalisation, dialysis, and even liver transplant.