Case Of Nonketotic Hyperglycinemia Research Articles

Identification of Two Novel Mutations in Aminomethyltransferase Gene in Cases of Glycine Encephalopathy.

In this study, we report three cases of nonketotic hyperglycinemia (NKHG) diagnosed biochemically and molecularly. Clinical exome analysis in two families revealed two novel mutations in the aminomethyltransferase (AMT) gene, that is, c.14_15insT (p.Ser6LysfsTer22) and c.259-2A > T, both of them adversely affecting the protein. This is the first report of AMT gene mutations in NKHG from India. Prenatal diagnosis in the first family showed an unaffected fetus in the third pregnancy. The role of AMT protein is pivotal for the synthesis of 5,10-methylene tetrahydrofolate, the first metabolite in one-carbon metabolism that regulates DNA synthesis, repair, and methylation.

Bridging the gap between metabolic profile determination and visualization in neurometabolic disorders: a multivariate analysis of proton magnetic resonance in vivo spectra

The purpose of this work was to check the degree of overlap between rare inborn errors of metabolism and other neurological disorders using principal component analysis of proton magnetic resonance spectroscopy (1H MRS) in vivo data. We examined 60 patients (median age of 22 months). Fourteen of them were diagnosed with neurometabolic disorders (three cases of metachromatic leukodystrophy, two cases of Canavan disease, two cases of megalencephalic leukoencephalopathy with subcortical cysts, three cases of mitochondrial cytopathy, one case of nonketotic hyperglycinemia, one case of globoid leukodystrophy, one case of congenital disorders of glycosylation, and one case of ethylmalonic encephalopathy). The remaining 46 patients were diagnosed with epilepsy, cerebral palsy, and developmental delay. Results obtained from principal component analysis of complete unresolved 1H MRS in vivo spectra were interpreted parallelly with LCModel‐derived metabolite levels. The main attention was paid to the following metabolites: N‐acetylaspartate, glutamate + glutamine, creatine, choline, myo‐inositol signal with an uncertain contribution of glycine, and glucose. 1H MRS in vivo coupled with multivariate analysis is an efficient tool in visualization of metabolic abnormalities in several inborn errors of metabolism (metachromatic leukodystrophy, globoid leukodystrophy, megalencephalic leukoencephalopathy with subcortical cysts, and Canavan disease). Copyright © 2013 John Wiley & Sons, Ltd.

Diagnostic tools of metabolic and structural brain disturbances in neonatal non‐ketotic hyperglycinemia

Non-ketotic hyperglycinemia (NKH) is a rare autosomal recessive disorder of glycine metabolism. We report a newborn case of NKH and discuss the effects of this rare disease on brain metabolism and structure together with amplitude-integrated electroencephalography, cranial magnetic resonance and magnetic resonance spectroscopy findings which are very rarely reported together so far.

Nonketotic hyperglycinemia: A case report and brief review

In encephalopathic infants, cerebrospinal fluid hyperglycinemia and elevated cerebrospinal fluid to plasma glycine ratio are considered pathognomonic of nonketotic hyperglycinemia (NKH). We present a case of NKH complicated by neonatal intractable seizures. Increased ratio of cerebrospinal fluid to plasma glycine concentrations of 0.28 was seen as a strong diagnostic indicator of nonketotic hyperglycinemia. Evaluating sick neonates with hypotonia, encephalopathy, and/or seizures is a diagnostic challenge. NKH should be considered; elevated cerebrospinal fluid/plasma glycine ratio will allow correct identification and treatment more often in the future.

Nonketotic Hyperglycinemia

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).

Cardiac Involvement in Nonketotic Hyperglycinemia

Nonketotic hyperglycinemia is an autosomal recessive disorder of glycine metabolism characterized by the accumulation of glycine in the serum and cerebrospinal fluid with elevated cerebrospinal fluid to serum glycine ratio. The disease primarily affects the central nervous system, and has not been previously associated with myocardial involvement. In this article, the authors report an infant with nonketotic hyperglycinemia, who was found to have progressive left ventricular hypertrophy and dysfunction. His older sibling, who had a similar neurologic presentation, died of dilated cardiomyopathy as stated by the parents. The authors speculate that glycine may have a role in the development of cardiac dysfunction. The incidence of cardiac involvement may be under-diagnosed. They suggest the need for a cardiac evaluation in confirmed cases of nonketotic hyperglycinemia.

Nonketotic hyperglycinemia in Suleimaniah Children’s Hospital, Riyadh, Saudi Arabia

Nonketotic hyperglycinemia in Suleimaniah Children’s Hospital, Riyadh, Saudi Arabia

Identification of a common mutation in Finnish patients with nonketotic hyperglycinemia.

Nonketotic hyperglycinemia (NKH) is an autosomal recessive metabolic disorder caused by the defects in the glycine cleavage system (GCS; EC 2.1.2.10), a multienzyme system that consists of four individual components. NKH is a rare disorder in many countries, but with a very high incidence in northern Finland. To understand the genetic background of this high incidence, we examined the GCS in a typical case of NKH at the molecular level. The activity of P protein, a component of the GCS, was not detected in the lymphoblasts of the patient, while P protein mRNA of a normal size and level was present in the cells. Structural analysis of P protein mRNA from the patient revealed a single nucleotide substitution from G to T in the protein coding region, which resulted in an amino acid alteration from Ser564 to Ile564. No P protein activity was detected when the mutant P protein with this amino acid substitution was expressed in COS 7 cells. The patient was homozygous for this mutation. Furthermore, this mutation was present in 70% (14 of 20) of P protein gene alleles in Finnish patients with NKH, whereas it was not found in 20 alleles of non-Finnish patients. The results suggest that this mutation is responsible for the high incidence of NKH in Finland.

The clinical findings in a patient with nonketotic hyperglycinemia.

A new case of nonketotic hyperglycinemia is reported. Hyperglycinemia, hyperglycinuria and mental retardation without neutropenia, thrombocytopenia, acidosis, ketosis, and the in vitro study of glycine-serine conversion in liver homogenate confirmed the diagnosis. Using electronmicroscopy osmiophobe, crystalline inclusions were found in lysosomes of liver parenchymal cells. These inclusions could be hippuric acid produced by increased conjugation of glycine.