Citrullinemia type I

Citrullinemia type I (CTLN1) presents as a clinical spectrum that includes an acute neonatal form (the "classic" form), a milder late-onset form (the "non-classic" form), a form without symptoms or hyperammonemia, and a form in which women have onset of severe symptoms during pregnancy or post partum. Distinction between the clinical forms is based on clinical findings and is not clear-cut. Infants with the acute neonatal form appear normal at birth. Shortly thereafter, they develop hyperammonemia and become progressively lethargic, feed poorly, often vomit, and may develop signs of increased intracranial pressure (ICP). Without prompt intervention, hyperammonemia and the accumulation of other toxic metabolites (e.g., glutamine) result in increased ICP, increased neuromuscular tone, spasticity, ankle clonus, seizures, loss of consciousness, and death. Children with the severe form who are treated promptly may survive for an indeterminate period of time, but usually with significant neurologic deficits. The late-onset form may be milder than that seen in the acute neonatal form, for unknown reasons. The episodes of hyperammonemia are similar to those seen in the acute neonatal form, but the initial neurologic findings may be more subtle because of the older age of the affected individuals.

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