Final answer:
Maple syrup urine disease is a metabolic disorder characterized by high levels of branched chain amino acids like valine, leucine, and isoleucine in the blood and CSF, due to a deficiency in a specific decarboxylase enzyme.
Step-by-step explanation:
In Maple syrup urine disease (MSUD), which is a metabolic disorder, there are elevated levels of branched chain amino acids in the body. These amino acids are valine, leucine, and isoleucine. The disease is due to a deficiency in the enzyme decarboxylase, which is necessary for the proper metabolism of these amino acids. As a result, an accumulation of them occurs in the blood and cerebrospinal fluid (CSF), and their corresponding keto acids are formed upon transamination, giving urine the characteristic sweet smell similar to maple syrup. This metabolic block also leads to diminished synthesis of proteins and lipoproteins, which can result in severe neurological damage due to the rapid degradation of brain tissue.