What is Carbamoyl Phosphate Synthetase I Deficiency (CPS-1)?

Jennifer and Rob were typical first-time parents. Though exhausted much of the time from caring for their baby boy, they doted on him and were thankful he appeared healthy and happy. It wasn't until their son was nearly three and Jennifer was once again pregnant that the toddler started acting lethargic, with little appetite. After several months of tests, his worried parents found out that he suffered from a condition known as carbamoyl phosphate synthetase-1 deficiency, commonly called CPS-1.

What is CPS-1?

This disorder is one example of a urea cycle defect, according to eMedicine. It's the result of a deficiency that creates an abundance of ammonia - a condition known as hyperammonia - in the body. Without the proper urea cycle, the body of an affected individual lacks the ability to properly dispose of waste nitrogen.

The body forms ammonia after breaking down proteins. If its levels get too high, the ammonia can become toxic.

CPS-1 is an inherited disease. Genetics Home Reference indicates that it follows an autosomal recessive pattern. This means that each parent of a child with this condition carries one copy of the defective gene but seldom shows any symptoms of the disorder. It also means that the disorder affects males and females equally. The illness is considered rare.

The specific gene responsible for CSP-1 is associated with chromosome 2. Experts have mapped it to band 2q35.

There are two types of carbamoyl phosphate synthetase-1 deficiency. The first affects newborns and is considered lethal. The less-severe, delayed-onset type can strike children or adults.

Signs and Symptoms of CPS-1

Although patients with CPS-1 exhibit a variety of symptoms, the one that appears to be common to nearly all of them is hyperammonia. Other symptoms can include anoxexia, labored or accelerated breathing, cerebral edema, irritability, combativeness and lethargy. Some patients vomit and experience disorientation, uncontrolled temperature, sleepiness, dullness and even coma. In rare cases, they might experience jerking movements known as asterixis.

Affected children typically experience poor growth. Papilledema, a swelling of the blind spot of the eye, might be present as the result of cerebral edema and raised pressure within the cranium. In the later stages of the disorder, patients sometimes experience apnea, respiratory failure and, in the case of the neonatal type, death.

Complications of CPS-1 can include developmental delays and intellectual disability. However, in some patients, particularly those with delayed-onset illness, signs can be less severe than those typically seen in newborns.

Treatment Options for CSP-1

Treatment for this condition involves careful monitoring, eMedicine also reports. The goal is to lower the patient's protein intake while preserving the level of energy intake. The treating doctor typically uses an intravenous (IV) infusion containing at least 10 percent glucose and lipids.

Some patients respond to IV sodium benzoate and sodium phenylacetate, along with arginine. This type of infusion is complex and is usually performed at a major medical center. It is also essential that physicians meticulously monitor the diet of a patient with CPS-1, as the requirements often change with age and as the result of other events.

When a patient has an unusually high level of ammonia in the blood, doctors order immediate hemodialysis, since this is considered a very serious condition.

Among the types of professionals most like to treat a patient suffering from carbamoyl phosphate synthetase-1 deficiency are medical geneticists, metabolic disease specialists and dietitians.

Sources:

http://emedicine.medscape.com/article/942159-overview

http://ghr.nlm.nih.gov/condition/carbamoyl-phosphate-synthetase-i-deficiency#resources

http://emedicine.medscape.com/article/942159-treatment