Carbamoyl phosphate synthetase I (CPS1) deficiency is a rare type of urea cycle disorder (UCD) that results from a genetic disorder of the CPS1 enzyme. This disorder follows the autosomal recessive mode of inheritance and often leads to multiple episodes of hyperammonemia, toxic levels of ammonia in the blood. The neonatal-onset patient with CPS1D usually appears healthy at birth but quickly deteriorates into severe symptoms. It is expected to impact one in every 300,000 to one in every 1.3 million babies.
UCDs are a set of nitrogen detoxification inborn abnormalities that affect around one in every 35,000 people, making them rare diseases, sometimes known as orphan diseases. UCDs can result in serious illness, including life-threatening hyperammonemia and changes in the usual amounts of intermediate metabolites.
CPS1D is caused by mutations in the CPS1 gene, which is a gene that gives instructions on how to make the carbamoyl phosphate synthetase I enzyme. This enzyme controls the first step of the urea cycle that involves incorporating excess nitrogen molecules into the cycle to be digested. However, in CPS1D, the carbamoyl phosphate synthetase I enzyme is weak or missing, preventing the urea cycle from functioning normally.
CPS1D can be diagnosed through mutation analysis, clinical presentation, biochemical tests, and genetic testing. It is currently being treated in accordance with the recommendations for UCDs, which is mostly focused on lowering dietary protein intake, detoxifying hyperammonemia, reversing endogenous catabolism, and reestablishing anabolism. For patients with neonatal-onset CPS1D, early liver transplantation can correct metabolic problems, but not neurological consequences.
In conclusion, CPS1 deficiency is a rare type of urea cycle disorder that arises from an inborn error of metabolism. Proper diagnosis and treatment are crucial in managing the symptoms and preventing central nervous system damage or even death.
