Neonatal-type nonketotic hyperglycinemia treatment remains unsatisfactory, even if started early. A review of six patients who underwent treatment for neonatal-type nonketotic hyperglycinemia in our hospital is presented. All patients were treated with a standardized protocol. Medical histories were retrieved from case notes. All six patients had elevated cerebrospinal fluid plasma glycine levels initially. All but one had received sodium benzoate and dextromethorphan from 1 month of age. All suffered from intractable seizures and severe mental retardation, and only two patients remain alive. One patient died at 5 days of age. No resuscitation was attempted in accordance with the family's wish after genetic counseling. The prognosis of neonatal nonketotic hyperglycinemia remains poor with current treatment. Genetic counseling helps parents cope with this devastating genetic disease.
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http://dx.doi.org/10.1177/08830738040190010702 | DOI Listing |
Nonketotic hyperglycinemia (NKH), also known as glycine encephalopathy, is a rare inherited neurometabolic disorder caused by a deficiency in the glycine cleavage enzyme system (GCS), leading to the pathological accumulation of glycine in blood and cerebrospinal fluid (CSF). This case report details a neonate presenting with central apnea, profound hypotonia, and refractory seizures, alongside prenatal findings of polyhydramnios and hiccup-like fetal movements, all strongly suggestive of severe NKH. Diagnostic evaluation confirmed markedly elevated glycine levels in serum and CSF, with a CSF-to-plasma glycine ratio exceeding 0.
View Article and Find Full Text PDFJA Clin Rep
December 2024
Department of Anesthesiology, Niigata University Medical and Dental Hospital, 1-754 Asahimachi-Dori, Chuo-Ku, Niigata, 951-8520, Japan.
Background: Non-ketotic hyperglycinemia (NKH) is a rare autosomal recessive disorder caused by defects in the glycine cleavage system, leading to elevated glycine levels in the central nervous system. NKH manifests in various forms, with the neonatal type being the most severe and often associated with high mortality and significant neurological impairment. This case report highlights the successful uses of desflurane and nitrous oxide for anesthetic management in a patient with NKH.
View Article and Find Full Text PDFMol Genet Metab
November 2024
Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado, Aurora, CO 80045, USA. Electronic address:
The recognition of glycine as an endogenous ligand at the allosteric activation site of the NMDA-type glutamatergic receptor led to the assumption that the excess glycine in nonketotic hyperglycinemia would result in overactivation of these receptors, and of the proposed use of inhibitors such as dextromethorphan or ketamine as a therapeutic agent. Years later it was recognized that these same receptors have an alternative endogenous activator d-serine, which is markedly decreased in nonketotic hyperglycinemia. This may result in underactivation of these NMDA-type glutamatergic receptors, challenging the earlier hypothesis.
View Article and Find Full Text PDFFront Genet
September 2024
Service de Neurologie Pédiatrique, CHU Bordeaux, University Bordeaux, CNRS, INCIA, UMR 5287, NRGen Team, Bordeaux, France.
Rev Neurol
September 2024
Hospital Universitario Miguel Servet, Zaragoza, España.
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