Nonketotic hyperglycinemia: a case report

*Correspondence: [e-mail].

Abstract

Case Presentation: A 2-month-old infant, born by c-section, 38 weeks, was diagnosed intrauterine with congenital clubfoot. He presented with episodes of drowsiness since birth and had an episode of bronchoaspiration, where he was referred to a referral hospital. He was diagnosed with grade I pulmonary hypertension and remained on mechanical ventilation for 13 days and non-invasive ventilation for 9 days. After mechanical ventilation was discontinued, irritability, continued somnolence, and myoclonic spasms were observed. He was again hospitalized, where oral automatisms were observed, and he was introduced to phenobarbital. A treatable disease panel was taken, which showed intragenic deletion of exons 1 to 2 in heterozygosity in the GLDC gene. He was introduced to sodium benzoate and L carnitine at two months of age and was referred to this service for follow-up with nutrology. In his first visit, difficult to control seizures were evidenced, and he was admitted for evaluation and management with neurology. On physical exam, he presented significant irritability, axial hypotonia with appendicular hypertonia, hyperreflexia, oral automatisms associated with upward ocular version events, and myoclonias. He is currently taking Levetiracetam, Clonazepam, Phenobarbital, and Topiramate, with an improvement in the seizure pattern, but without control.

Discussion: Nonketotic hyperglycinemia is characterized by an inborn error of metabolism that manifests itself by seizures that are difficult to control due to the lack of an enzyme that catalyzes the conversion of glycine into carbon dioxide and ammonia in the liver and brain. The mutations occur frequently in the GLDC and AMT genes and are responsible for severe neurological symptoms such as intractable epilepsy, delayed neuropsychomotor development, and hypotonia. This patient did not need a glycine test to confirm the disease because he had already undergone a genetic test, which confirmed the diagnosis. The prognosis of the disease is poor, and the use of sodium benzoate has a positive effect on the treatment by reducing the levels of glycine in the blood. The use of L carnitine occurs because of the frequent deficiency of it, caused by the therapy with sodium benzoate.

Final Comments: Thus, greater investment is needed in formulations accessible to the population for the treatment of a disease that is difficult to control and manage, as well as multidisciplinary monitoring of patients to prevent complications related to the disease.

 

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Artikel online veröffentlicht:
12. Mai 2025