Ornithine Transcarbamoylase (OTC) deficiency is a disruption of the urea cycle. The urea cycle is the means through which the body gets rid of the surplus ammonium produced as a byproduct of aminoacid metabolism.
As indicated by its name, OTC introduces a carbamoyl subgroup into ornithine, and thus a new compound is synthesized, which is citrulline, the first molecule in the cycle of urea. The carbamoyl subgroup results from the combination of ammonium with carbon dioxide. As a result, when OTC is deficient, ammonium piles up (constitutional laboratory finding in OTC deficiency -- choice A is correct), as well as other intermediate products of urea cycle (such as ornithine and arginine), but this finding is not invariably evident (choice C is not correct).
OTC deficiency provokes an apparent malfunction of the urea cycle, consequently urea is UNDERproduced (choice B is incorrect).
As already mentioned, OTC produces citrulline from carbamoyl phosphate & ornithine, thus OTC deficiency causes low levels of citrulline (choice D is incorrect).
Putrescin is a molecule also deriving from the catabolism of aminoacids in decaying tissues and is notorious for the odors produced in bacterial vaginosis, bad breath and decomposing corps. In this case, the surplus ammonium, instead of combining with carbon dioxide, it attaches to an aliphatic carbon chain. If I am correct, OTC does not take part in this process (choice E is incorrect).
Waiting impatiently for your comments and corrections!
