From OMIM
Ornithine transcarbamylase deficiency is an X-linked inborn error of metabolism of the urea cycle, which causes hyperammonemia. The disorder is treatable with supplemental dietary arginine and low protein diet. Urea cycle disorders are characterized by the triad of hyperammonemia, encephalopathy, and respiratory alkalosis. Five disorders involving different defects in the biosynthesis of the enzymes of the urea cycle have been described: OTC deficiency, carbamyl phosphate synthetase deficiency (237300), argininosuccinate synthetase deficiency, or citrullinemia (215700), argininosuccinate lyase deficiency (207900), and arginase deficiency (207800).  http://www.omim.org/entry/311250

From MedlinePlus Genetics
Ornithine transcarbamylase deficiency is an inherited disorder that causes ammonia to accumulate in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if the levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

Ornithine transcarbamylase deficiency can become evident at any age. The most severe form occurs in the first few days of life. This neonatal-onset form of the disorder usually affects males; it is very rare in females. An infant with the neonatal-onset form of ornithine transcarbamylase deficiency may be lacking in energy (lethargic) or unwilling to eat, and have a poorly-controlled breathing rate or body temperature. Infants with this disorder may be described as "floppy" and can experience seizures or coma. Complications from ornithine transcarbamylase deficiency may include developmental delay and intellectual disability. Progressive liver damage may also occur.

In some affected individuals, signs and symptoms of ornithine transcarbamylase deficiency may be less severe, and may not appear until later in life. The late-onset form of the disorder occurs in both males and females. People with late-onset ornithine transcarbamylase deficiency may experience episodes of altered mental status, such as delirium, erratic behavior, or a reduced level of consciousness. Headaches, vomiting, aversion to protein foods, and seizures can also occur in this form of the disorder.  https://medlineplus.gov/genetics/condition/ornithine-transcarbamylase-deficiency