Our diet supplies the amino acids and proteins that are very essential for normal growth and functions of our body. These amino acids and proteins contain nitrogen and when they are broken down, the nitrogen has to be disposed. The urea cycle is a pathway that is essential to get rid of excess waste nitrogen from the body. The enzymes (proteins that speed up the making or breaking of compounds) and the transporters (channels that allow proteins to move within the cells of the body) of the urea cycle help convert this waste nitrogen from ammonia (a toxic product produced by the body) into urea. In urea cycle disorders, there is a deficiency of one of the six enzymes (NAGS, CPS1, OTC, ASS1, ASL, and ARG1) or two transporters (ORNT1 and Citrin) required to make urea, and the inability to dispose of nitrogen leads to a toxic build up of ammonia. Children with severe forms of urea cycle disorders can present within the first few days of life whereas those with milder forms may present later in childhood, and some even in adulthood.