Article

Hyperglycinemia: Innate Errors of Metabolism

Abstract

Innate errors of metabolism are biochemical disorders of genetic origin that cause a specific defect in the structure or function of the protein molecules involved in a metabolic pathway. Hyperglycinemia, or elevation of glycine in the blood, occurs in different metabolic diseases related to a disorder of the metabolism of the amino acid glycine. It is inherited with recessive autonomic character. Two varieties are distinguished: primary or nonketotic hyperglycemia and secondary or ketotic hyperglycemia. The so-called primary or non ketotic hyperglycemia corresponds to a congenital disorder of glycine metabolism and presents with an elevation of cerebral glycine, without an increase in ketoacids. It is the most common of the hyperglycinemia’s due to a congenital deficiency of the glycine converting enzyme. Ketotic hyperglycinemia is secondary to organ acidemias, thus differing from the previous ones in that there are ketoacids and glycine increases little in the nervous system. They occur due to a blockage of the glycine converting enzyme and are due to external inhibition.

Keywords: Inborn errors of metabolism, glycine, nonketotic hyperglycemia primary, and ketotic hyperglycinemia secondary.