In its purified form, malonic acid is a white, crystalline substance, water-soluble and easily decomposed by heat. Chemically, it is an organic dicarboxylic acid with a methylene group separating the two carbonyl moieties. The diethyl ester of this chemical is used chiefly as an intermediate in the synthesis of barbiturates. It is also used to synthesize vitamins B1 and B6 as well as numerous other organic compounds. The free acid is rather unstable and has few uses other than being a biochemical diagnostic probe for intermediary metabolism. The calcium salt of malonic acid occurs in beetroot, but the acid itself is usually prepared by hydrolyzing diethyl malonate. It undergoes the usual reactions of carboxylic acids as well as facile cleavage into acetic acid and carbon dioxide. Malonic acid is a normal component of human urine, in small quantities, but a genetic disorder called methyl malonic aciduria (also known as malonic aciduria or Malonyl-CoA decarboxylase deficiency) causes high levels of methyl malonic acid in the blood serum and urine. Patients with this disorder suffer from severe metabolic acidosis and a metabolic block in the vitamin B12 dependent conversion of propionyl CoA to succinyl CoA. In infants, symptoms can include developmental delay, cardiomyopathy, mental retardation, and in its more severe forms, neonatal death. Malonyl-CoA decarboxylase deficiency is a condition that prevents the body from converting certain fats to energy. The signs and symptoms of this disorder typically appear in early childhood. Almost all affected children have delayed development. Additional signs and symptoms can include weak muscle tone (hypotonia), seizures, diarrhea, vomiting, and low blood sugar (hypoglycemia). A heart condition called cardiomyopathy, which weakens and enlarges the heart muscle, is another common feature of malonyl-CoA decarboxylase deficiency. Mutations in the MLYCD gene cause malonyl-CoA decarboxylase deficiency. The MLYCD gene provides instructions for making an enzyme called malonyl-CoA decarboxylase. Within cells, this enzyme helps regulate the formation and breakdown of a group of fats called fatty acids. Many tissues, including the heart muscle, use fatty acids as a major source of energy. Mutations in the MLYCD gene reduce or eliminate the function of malonyl-CoA decarboxylase. A shortage of this enzyme disrupts the normal balance of fatty acid formation and breakdown in the body. As a result, fatty acids cannot be converted to energy, which can lead to characteristic features of this disorder including low blood sugar and cardiomyopathy. By-Products of fatty acid processing build-up in tissues, which also contributes to the signs and symptoms of malonyl-CoA decarboxylase deficiency.

Resources:

- https://pubmed.ncbi.nlm.nih.gov/?term=12651823%2C16078122%2C24613099%2C3709568%2C9177981%2C7609455%5Buid%5D

- https://pubmed.ncbi.nlm.nih.gov/23177061/

- https://www.mdpi.com/2409-515X/3/1/5/htm

- https://ghr.nlm.nih.gov/condition/malonyl-coa-decarboxylase-deficiency