Parviz Samaneh, Hooshyar Dariush
Department of Pediatrics, Clinical Research Development Center of Children's Hospital Hormozgan University of Medical Science Bandar Abbas Iran.
Student Research Committee, Faculty of Medicine Hormozgan University of Medical Sciences Bandar Abbas Iran.
Clin Case Rep. 2025 Jan 6;13(1):e70035. doi: 10.1002/ccr3.70035. eCollection 2025 Jan.
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.
非酮症高甘氨酸血症（NKH），也称为甘氨酸脑病，是一种罕见的遗传性神经代谢紊乱疾病，由甘氨酸裂解酶系统（GCS）缺乏引起，导致血液和脑脊液（CSF）中甘氨酸病理性蓄积。本病例报告详细描述了一名新生儿，出现中枢性呼吸暂停、严重肌张力低下和难治性癫痫发作，同时产前检查发现羊水过多和类似打嗝的胎儿运动，所有这些都强烈提示严重的NKH。诊断评估证实血清和脑脊液中甘氨酸水平显著升高，脑脊液与血浆甘氨酸比值超过0.08，并排除了高甘氨酸血症的其他原因。脑部磁共振成像（MRI）显示出特征性畸形，进一步证实了严重NKH的诊断。治疗包括使用抗惊厥药物控制癫痫发作、苯甲酸钠降低甘氨酸水平，以及使用N-甲基-D-天冬氨酸（NMDA）受体拮抗剂（氯胺酮和右美沙芬）调节神经毒性。尽管采取了这些治疗措施，患者的神经发育结局仍较差，并迅速进展为严重损伤。本病例强调了早期识别、准确诊断和全面护理策略在NKH管理中的重要性，旨在改善患者结局和生活质量。
