Citrullinemia, Type I (CIT-I)



Citrullinemia, type I (also known as classic citrullinemia or CIT) usually becomes evident in the first few days of life. Affected babies typically appear normal at birth, but as ammonia builds up they experience a progressive lack of energy (lethargy), poor feeding, vomiting, seizures, and loss of consciousness. Some affected individuals develop serious liver problems. The health problems associated with CIT are life-threatening in many cases. Less commonly, a milder form of CIT can develop later in childhood or adulthood. This later-onset form is associated with intense headaches, blind spots (scotomas), problems with balance and muscle coordination (ataxia), and lethargy. Some individuals with gene mutations that cause CIT never experience symptoms of the condition.

Condition Type:

Core Conditions


Citrullinemia, type I (CIT) affects about 1 in 57,000 people worldwide.

More Information for Parents:
Also known as:
  • Citrullinuria (type I)
  • Citrullinemia (type I)
  • Argininosuccinic acid synthetase deficiency (type I)
  • ASAS (Type I)
  • Argininosuccinate synthase deficiency (type I)
  • CIT
  • Classic citrullinemia

Core Conditions