Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management

ABSTRACT 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 repor...

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Main Authors: Samaneh Parviz, Dariush Hooshyar
Format: Article
Language:English
Published: Wiley 2025-01-01
Series:Clinical Case Reports
Subjects:
Online Access:https://doi.org/10.1002/ccr3.70035
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author Samaneh Parviz
Dariush Hooshyar
author_facet Samaneh Parviz
Dariush Hooshyar
author_sort Samaneh Parviz
collection DOAJ
description ABSTRACT 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 0.08, and ruled out alternative causes of hyperglycinemia. Brain MRI revealed characteristic malformations, corroborating the diagnosis of severe NKH. Treatment included anticonvulsants for seizure management, sodium benzoate for glycine reduction, and NMDA receptor antagonists (ketamine and dextromethorphan) to modulate neurotoxicity. Despite these therapies, the patient demonstrated poor neurodevelopmental outcomes, with rapid progression to severe impairment. This case highlights the significance of early identification, precise diagnosis, and a comprehensive care strategy in managing NKH, aiming to enhance patient outcomes and quality of life.
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spelling doaj-art-5aabd5008a1f469994c6779f93a10c452025-01-24T05:08:46ZengWileyClinical Case Reports2050-09042025-01-01131n/an/a10.1002/ccr3.70035Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and ManagementSamaneh Parviz0Dariush Hooshyar1Department of Pediatrics, Clinical Research Development Center of Children's Hospital Hormozgan University of Medical Science Bandar Abbas IranStudent Research Committee, Faculty of Medicine Hormozgan University of Medical Sciences Bandar Abbas IranABSTRACT 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 0.08, and ruled out alternative causes of hyperglycinemia. Brain MRI revealed characteristic malformations, corroborating the diagnosis of severe NKH. Treatment included anticonvulsants for seizure management, sodium benzoate for glycine reduction, and NMDA receptor antagonists (ketamine and dextromethorphan) to modulate neurotoxicity. Despite these therapies, the patient demonstrated poor neurodevelopmental outcomes, with rapid progression to severe impairment. This case highlights the significance of early identification, precise diagnosis, and a comprehensive care strategy in managing NKH, aiming to enhance patient outcomes and quality of life.https://doi.org/10.1002/ccr3.70035antiepileptic drugsglycine encephalopathyhiccup‐like movementsneonatal nonketotic hyperglycinemiaprenatal indicators
spellingShingle Samaneh Parviz
Dariush Hooshyar
Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
Clinical Case Reports
antiepileptic drugs
glycine encephalopathy
hiccup‐like movements
neonatal nonketotic hyperglycinemia
prenatal indicators
title Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
title_full Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
title_fullStr Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
title_full_unstemmed Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
title_short Neonatal Nonketotic Hyperglycinemia: A Severe Case With Prenatal Indicators and Comprehensive Review of Recognition and Management
title_sort neonatal nonketotic hyperglycinemia a severe case with prenatal indicators and comprehensive review of recognition and management
topic antiepileptic drugs
glycine encephalopathy
hiccup‐like movements
neonatal nonketotic hyperglycinemia
prenatal indicators
url https://doi.org/10.1002/ccr3.70035
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