nonketotic hyperglycinemia /nonkētot′ik/ , a usually fatal autosomal-recessive aminoacidopathy with accumulation of glycine in body fluids, particularly the blood, urine, and cerebrospinal fluid. It has neonatal onset and is characterized by lethargy, metabolic acidosis with ketosis, absence of cerebral development, seizures, myoclonic jerks, and frequently coma and respiratory failure. It is caused by a defect in one or more of the enzymes involved in the cleavage of glycine. Also called methylmalonicacidemia, propionicacidemia.
