ABSTRACT
Nonketotic hyperglycinemia is an inborn error of amino acid metabolism in which large amounts of glycine accumulate in body fluids, and there is no demonstrable accumulation of organic acids. A majority of patients has the classic phenotype in which life-threatening illness begins in the early days of life, and most patients die if not maintained by the use of mechanical ventilation. Survivors usually display little cognitive development and often have virtually continuous seizures. The disease was first described by Gerritsen, Kaveggia and
Waisman in 1965 [1]. It was called nonketotic hyperglycinemia to distinguish it from other disorders, such as propionic acidemia (Chapter 2), in which hyperglycinemia occurs [2,3]. The high concentration of glycine in the cerebrospinal fluid (CSF) and the ratio of its concentration to that of the plasma provide the usual method of diagnosis. Analysis of organic acids of the urine is useful to exclude organic academia. Enzyme analysis is not generally available; the enzyme is fully expressed only in liver and brain.
