Urea cycle disorders (UCDs) are a group of rare inborn errors of metabolism caused due to genetic defects that affect the enzymes involved in the urea cycle. The urea cycle is a process in the liver which converts ammonia, a waste product of protein metabolism, into urea which gets excreted in urine. A defect in any of the six enzymes involved in this cycle results in elevated levels of ammonia in the blood (hyperammonemia), which can damage the brain and be life-threatening if not treated promptly.