We received an official diagnosis today from his liver biopsy. The specific Urea Cycle Disorder is called Carbamoyl Phosphate Synthetase Deficiency (CPS).

“Carbamoyl phosphate synthetase (CPS) deficiency is a urea cycle defect that results from a deficiency in an enzyme that mediates the normal path for incorporation of ammonia” (Roth, 2007).

emedicine website Roth, K. (2007) retrieved from http://emedicine.medscape.com/article/942159-overview

United States

CPS deficiency is rare. As with all the urea cycle defects, as well as most of the inborn errors, citing incidence figures is impossible because new cases are generally diagnosed randomly without the benefit of population screening.

Mortality and morbidity rates are high. Untreated CPS deficiency is likely fatal.

The multiple primary causes of hyperammonemia, specifically those due to urea cycle enzyme deficiencies, vary in manifestation, diagnostic features, and management. For these reasons, the urea cycle defects are considered individually in this article; however, hyperammonemia is the common denominator and generally manifests clinically as a common constellation of signs and symptoms. As a consequence, the most striking clinical findings of each individual urea cycle disorder relate to this constellation of symptoms and rough temporal sequence of events.

Symptoms include the following:
Anorexia, Irritability, Heavy or rapid breathing, Lethargy, Vomiting, Disorientation, Somnolence,
Asterixis (rare), Combativeness, Obtundation, Coma, Cerebral edema, death

Other websites:

CPS http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=237300
National Urea Cycle Foundation http://www.nucdf.org/index.htm

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  1. Even though Lennon has had a transplant and no longer has CPS it must be a relief to have found out what he actually has. Is a liver biopsy the only way to diagnose CPS? If they had known he had CPS before would they have made any changes to his treatment that would have stabalized him more, or is this type of UCD pretty much unstable and impossible to manage? My brief readings show that this is a very severe form of UCD and I’m guessing having the diagnosis makes you feel more confident and assured that a liver transplant was the right way to go. It must be so difficult at this time of uncertainty … hang in there just like Lennon is doing.

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