Abstract
Urea cycle disorders (UCDs) are inborn errors of ammonia detoxification/arginine synthesis
due to defects affecting the catalysis of the Krebs-Henseleit cycle (five core enzymes,
one activating enzyme and two transporters). The hallmark of urea cycle (UC) dysfunction
is hyperammonemia, due to the impossibility of detoxifing ammonia derived from dietary
protein intake, muscle catabolism or bacterial production within the intestine. Beside
primary defects of one of the enzymes or transporters, other genetic or acquired conditions
can secondary affect, by different mechanisms, UC function, hereby leading to hyperammonemia.
Aim of this paper is to review the most important genetic conditions responsible of
UC function impairment, to highlight the connection with UC enzymes and to provide
the clue for differential diagnosis.
Keywords
UCD - urea cycle - hyperammonemia - secondary hyperammonemia
