title: Nonketotic hyperglycinemia: a cause of encephalopathy in children.
abstract: Nonketotic hyperglycinemia is a rare metabolic disorder with severe, frequently fatal, neurologic manifestations. Reliable and accurate diagnosis depends on careful interpretation of laboratory findings. The clinical suspicion should lead to determination of glycine in plasma and cerebrospinal fluid. Amino acid analysis presents diagnostic values for classic nonketotic hyperglycinemia, but it also should be performed in suspected cases of atypical nonketotic hyperglycinemia and in children with seizures, failure to thrive, behavior problems, and uncoordinated movements. Clinical assessment should be reinforced by demonstration of elevated cerebrospinal fluid-to-plasma glycine ratio. Confirmatory diagnosis requires enzymatic and genetic investigation of glycine cleavage system. An early diagnosis, though not affecting clinical outcome, allows proper genetic counseling, with the possibility of prenatal diagnosis. We report 3 cases of nonketotic hyperglycinemia, 2 typical neonatal and 1 atypical, diagnosed in Pediatric Hospital of Coimbra, Portugal, and investigated at Laboratory of Biochemical Genetics in 2004 to 2010 (incidence 1:47 455; prevalence 1:782 951).
authors.affiliation: Centro de Neurociências e Biologia Celular, Universidade de Coimbra, Laboratório de Bioquímica Genética, Coimbra, Portugal.
authors.forename: Carla
authors.initials: C
authors.lastname: Veríssimo
authors.forename: Paula
authors.initials: P
authors.lastname: Garcia
authors.forename: Marta
authors.initials: M
authors.lastname: Simões
authors.forename: Conceição
authors.initials: C
authors.lastname: Robalo
authors.forename: Raquel
authors.initials: R
authors.lastname: Henriques
authors.forename: Luísa
authors.initials: L
authors.lastname: Diogo
authors.forename: Manuela
authors.initials: M
authors.lastname: Grazina
mesh_terms: D002648:Child; D005260:Female; D005998:Glycine / Q000097:blood / Q000134:cerebrospinal fluid; D006801:Humans; D020158:Hyperglycinemia, Nonketotic / Q000097:blood / Q000134:cerebrospinal fluid / Q000150:complications*; D008607:Intellectual Disability / Q000097:blood / Q000134:cerebrospinal fluid / Q000209:etiology*; D065768:Lennox Gastaut Syndrome; D008297:Male; D013036:Spasms, Infantile / Q000097:blood / Q000134:cerebrospinal fluid / Q000209:etiology*
chemical_list: D005998:Glycine