non-ketotic hyperglycinemia

Non-ketotic hyperglycinemia is a metabolic disorder characterized by elevated levels of the neurotransmitter glycine in the central nervous system. This condition arises from a defect in the enzyme system responsible for cleaving the amino acid glycine. Symptoms typically include seizures, low muscle tone, hiccups, breath-holding, and severe developmental impairment. While there is no cure, treatments such as drugs that block glycine's action, a low-protein diet, and glycine-scavenging medications may help alleviate symptoms. This disorder is one of several affecting amino acid metabolism, which are generally inherited in an autosomal recessive pattern.12