Neonatal nonketotic hyperglycinemia: a case report and literature review / 中国新生儿科杂志

Objective:To study the phenotypes and genotypes of neonatal nonketotic hyperglycinemia (NKH).Methods:A neonate with severe NKH admitted to our hospital was retrospectively analyzed. Using keywords 'glycine cleavage enzyme', 'glycine decarboxylase', 'nonketotic hyperglycinemia' and 'glycine encephalopathy' (both in Chinese and English), multiple medical databases were searched until December 31, 2022. The clinical phenotypes and genotypes of neonatal NKH were summarized.Results:For our case, the neonate was lethargy and had no appetite on the second day of life, followed by recurrent seizures and irregular breathing, requiring mechanical ventilation. She died at 3 weeks of age. Two compound heterozygous variants were found in GLDC gene from whole exome sequencing , one was c.848C>G(p.A283G) of maternal origin and one was c.1607G>A(p.R536Q) of paternal origin. The former was a novel mutation. A total of 54 cases (including this case) were collected. The main clinical manifestations included poor feeding, decreased muscle tone, hiccups, progressive lethargy, irregular breathing, apnea and neonatal seizures. 42 cases (77.8%) had GLDC gene mutations, 9 cases (16.7%) had AMT gene mutations, 2 cases (3.7%) had LIAS gene mutations and 1 case (1.9%) had GCSH gene mutations. Conclusions:Neurological manifestations are most common in neonatal NKH with wide clinical variations. GLDC gene mutations are the predominant pathogenic mutations.

Advances in nonketotic hyperglycinemia / 国际儿科学杂志

Nonketotic hyperglycinemia(NKH), also known as glycine encephalopathy, is a rare and life-threatening autosomal recessive disease.Due to the insufficient activity of the glycine cleavage enzyme system(GCS), glycine can not be degraded and accumulates in the body.It leads to progressive damage to the nervous system.The clinical manifestations of the disease vary.Based on ultimate outcome, NKH is categorized into severe NKH and attenuated NKH.It is characterized by increased glycine level in cerebrospinal, and further confirmatory tests are molecular genetic testing and enzymatic testing.So far, no causal treatment of NKH has been discovered and the overall prognosis is still poor.The therapy is based on sodium benzoate and N-methyl-D-aspartate(NMDA)receptor site antagonists.This article reviews the progress of NKH, in order to help clinicians comprehensively identify NKH and take proactive measures to get the best results.

Phenotypic and genetic analysis of a family with nonketotic hyperglycinemia caused by AMT gene mutation / 中华神经科杂志

Nonketotic hyperglycinemia (NKH) is a rare congenital metabolic disorder with low diagnostic rate. This article reported a case of NKH caused by AMT gene mutation. The child started with suspected neonatal sepsis, and then the condition deteriorated rapidly, including apnea, hiccup, coma, convulsion, etc. Blood glucose, ketone body, blood gas analysis of electrolytes, blood ammonia and so on were generally normal. Blood and urine screening results showed that glycine was slightly higher, and the ratio of cerebrospinal fluid to serum glycine concentration increased. Electroencephalogram showed outburst suppression. High total exome sequencing results showed that the maternal exon 3 c.664C>T(p.Arg222Cys) of AMT gene was pathogenic, and the paternal exon 3 c.793C>T(p.Arg265Cys) was suspected to be pathogenic, which was an autosomal recessive genetic disease with complex heterozygosis. The clinical diagnosis and treatment of this child and the characteristics of gene mutation are summarized.

Hiperglicinemia no cetósica neonatal, fenotipo atenuado / Neonatal nonketotic hyperglycinemia, attenuated phenotype / Hiperglicinemia não-cetótica neonatal, fenótipo atenuado

Introducción. La Hiperglicinemia no Cetósica (HNC) es un error innato del metabolismo de herencia autosómica recesiva, cuya principal característica es la acumulación de glicina en los fluidos corporales, producido por una falla en el complejo de clivaje enzimático de este aminoácido. Presentación del caso. Presentamos el caso de un recién nacido de 36 semanas, con adaptación neonatal espontánea, sin historia de noxa perinatal ni hipoglicemia documentada, quien tras un corto período de 24 horas presentó deterioro neurológico progresivo, rápida alteración del estado de conciencia hasta el coma y falla ventilatoria. Llamó la atención al ingreso la hipotonía severa generalizada, hiporreflexia, ausencia de reflejos primitivos, con episodios de hipo aislado y movimientos oculares anormales. Ante la sospecha de un error innato del metabolismo se realizó el perfil de aminoácidos donde se evidenció elevación significativa de la glicina, 1417 mmol/L (referencia 94-553 umol/L). Se solicitaron aminoácidos en líquido cefalorraquídeo, glicina muy elevada 1263 mmol/L (referencia 3-7 umol/L), con lo que se confirma la sospecha de hiperglicinemia no cetósica. Se decidió iniciar manejo con benzoato de sodio y dextrometorfano. La resonancia magnética inicial fue normal, en estudio control se encontraron al igual que en el electroencefalograma hallazgos reportados previamente en la literatura para esta patología. Discusión. La mayoría de los niños con HNC se presentan en el período neonatal o en la primera infancia, y solo los casos más leves se presentan al final de la infancia o la niñez. En las presentaciones de inicio neonatal, el 85% tiene HNC grave y el 15% tiene forma atenuada, como este caso. El diagnóstico de la HNC se hace con base en la sospecha clínica, confirmada por los hallazgos de laboratorio, con la alteración característica de la glicina tanto en plasma como en el LCR y soportada por los hallazgos de las neuroimágenes y electroencefalograma (EEG). Conclusiones. La HNC no es una condición tan inusual, aunque sí posiblemente subdiagnosticada por la forma de presentación tan catastrófica, además porque no produce grandes desarreglos metabólicos de rápido diagnóstico. Por este motivo, ante un paciente con cuadro clínico sugestivo, con coma, alteración respiratoria y convulsiones de difícil manejo, y muy característicamente hipo, debe solicitarse el estudio de aminoácidos en plasma, neuroimágenes y EEG, con el fin de instaurar un manejo temprano.

Introduction. Nonketotic hyperglycinemia (NKH) is an autosomal recessive innate error of metabolism, whose main characteristic is the accumulation of glycine in body fluids, produced by a failure in the enzymatic cleavage complex of this amino acid. Case Presentation. We present the case of a 36-week-old newborn, with spontaneous neonatal adaptation, no history of perinatal noxa or documented hypoglycemia, who after a short period of 24 hours presented progressive neurological deterioration, rapid alteration of consciousness to coma and ventilatory failure. At admission the patient was noted for severe generalized hypotonia, hyporeflexia, absence of primitive reflexes, with episodes of isolated hiccups and abnormal eye movements. In view of the suspicion of an innate error of metabolism, an amino acid profile was performed, showing a significant elevation of glycine, 1417 umol/L (reference 94-553 umol/L). Amino acids were requested in cerebrospinal fluid, glycine very elevated 1263 umol/L (reference 3-7 umol/L), confirming the suspicion of nonketotic hyperglycinemia. It was decided to start treatment with sodium benzoate and dextromethorphan. The initial MRI was normal; in the control study, findings previously reported in the literature for this pathology were found, as well as in the electroencephalogram. Discussion. Most children with NKH will display it in the neonatal period or early infancy, with only the mildest cases presenting in late infancy or childhood. In neonatal-onset cases, 85% have severe NKH and 15% have attenuated form, as in this case. The diagnosis of NKH is made based on clinical suspicion, confirmed by laboratory findings, with the characteristic alteration of glycine in both plasma and CSF and supported by neuroimaging and electroencephalogram (EEG) findings. Conclusions. NKH is not such an unusual condition, although it is possibly underdiagnosed because of its catastrophic presentation and because it does not produce major metabolic disorders that are quickly diagnosed. For this reason, in a patient with a suggestive clinical condition, with coma, respiratory alteration and unmanageable seizures, and very characteristically hiccups, the study of amino acids in plasma, neuroimaging and EEG should be requested, in order to establish early treatment.

Introdução. A hiperglicinemia não-cetótica (HNC) é um erro inato do metabolismo de herança autossômica recessiva, cuja principal característica é o acúmulo de glicina nos fluidos corporais, produzido por uma falha no complexo de clivagem enzimática deste aminoácido. Apresentação do caso. Apresentamos o caso de um recém-nascido de 36 semanas, com adaptação neonatal espontânea, sem história de noxa perinatal nem hipoglicemia documentada, que após um curto período de 24 horas apresentou deterioração neurológica progressiva, alteração rápida de consciência até coma e falha ventilatória. Na admissão, eram notáveis a hipotonia grave generalizada, hiporreflexia, ausência de reflexos primitivos, com episódios de soluços isolados e movimentos oculares anormais. Diante da suspeita de erro inato no metabolismo, foi realizado o perfil de aminoácidos, onde foi constatada elevação significativa da glicina, 1417umol/L (referência 94-553 umol/L). Foram solicitados aminoácidos no líquido cefalorraquidiano, glicina muito alta 1263umol/L (referência 3-7 umol/L), confirmando a suspeita de hiperglicinemia não-cetótica. Foi decidido iniciar o tratamento com benzoato de sódio e dextrometorfano. A ressonância magnética inicial foi normal, tanto em estudo controle quanto no eletroencefalograma, foram encontrados achados previamente relatados na literatura para esta patologia. Discussão. A maioria das crianças com HNC estão no período neonatal ou na primeira infância, e apenas os casos mais leves ocorrem na infância ou na infância tardia. Nas apresentações de início neonatal, 85% têm HNC grave e 15% têm forma atenuada, como neste caso. O diagnóstico de HNC é feito com base na suspeita clínica, confirmada por achados laboratoriais, com alteração característica da glicina tanto no plasma quanto no LCR e apoiado por achados de neuroimagem e eletroencefalograma (EEG). Conclusões. A HNC não é uma condição tão incomum, embora possivelmente seja subdiagnosticada por sua apresentação catastrófica, também por não produzir grandes distúrbios metabólicos que possam ser diagnosticados rapidamente. Por esse motivo, em um paciente com quadro clínico sugestivo, com coma, distúrbios respiratórios e convulsões de difícil manejo, e soluços muito característicos, deve ser solicitado um estudo de aminoácidos no plasma, neuroimagem e EEG a fim de estabelecer um tratamento rápido.

Características electroclínicas en pacientes menores de 18 años con errores innatos del metabolismo (EIM) y epilepsia / Electro clinical characteristics in pediatric patients with inborn errors of metabolism (IEM) and epilepsy

INTRODUCCIÓN: Los errores innatos del metabolismo (EIM) son un grupo de enfermedades de origen genético, que entre el 40 % y el 60 % pueden manifestar crisis convulsivas. OBJETIVO: En este estudio se establecieron las características clínicas y electroencefalográficas en una muestra de 20 niños con diagnóstico de EIM y epilepsia. MATERIALES Y METODOS: La metodología utilizada fue un estudio descriptivo de series de casos retrospectivo. RESULTADOS: El 65 % de los pacientes de la muestra eran niños, el EIM de moléculas pequeñas fue el más frecuente (70 %). En cuanto a las variables clínicas, 90 % tenían encefalopatía, 75 % epilepsia refractaria y 55 °% crisis generalizadas. En electroencefalografía (EEG), 90 % de los pacientes tenían ritmo de fondo anormal, 80 % grafoelementos del sueño mal estructurados, 36 % de los afectados por EIM de moléculas pequeñas tenían patrón EEG multifocal y 100 % de los pacientes con déficit de producción de energía tuvieron patrón EEG focal. CONCLUSION: El tipo de EIM más frecuente en el estudio fue de moléculas pequeñas, con grados variables de encefalopatía y epilepsia refractaria. La anormalidad electroencefalográfica más frecuente fue el ritmo de fondo anormal debido a grafoelementos de sueño mal estructurados, en tanto que el patrón eléctrico fue dependiente de la edad y el tipo de EIM.

SUMMARY INTRODUCTION: Inborn errors of metabolism (IEM) are a group of diseases of genetic origin and they may manifest with seizures at some point of their evolution such as 40 to 60 percent of cases. SUBJECT: In this study, the clinical and electroencephalographic characteristics were established in a sample of 20 children diagnosed with IEM and epilepsy. METHODS: The methodology was a descriptive way of retrospective case series. RESULTS: The group was constituted 65 % by males. The EIM of small molecules was the most frequent (70 %). Regarding the clinical variables, 90 % had encephalopathy, 75 % refractory epilepsy and 55 % generalized epilepsy. About the electroencephalographic facts, 90 % had an abnormal basal activity, 80 % poorly structured sleep elements. The most frequent electroencephalographic pattern in small molecules disease's patients was multifocal (36 %) but in deficit of energy production's patients was focal (100 %). CONCLUSION: The type of IEM that predominated in this study was small molecules, with varying degrees of encephalopathy and refractory epilepsy. The most frequent electroencephalographic variable was abnormal background rhythm, with poorly structured sleep graphoelements. The electroencephalographic pattern depends on the age and type of IEM.

Hiperlisinemia Como Hallazgo Sugestivo De Acidemia Propiónica. Reporte De Caso / Hyperlisinemia As A Suggestive Finding Of Propionic Acidemia. Case Report

RESUMEN Introducción: La acidemia propiónica (AP) es una acidemia orgánica (AO) con presentación clínica de inicio neonatal o de forma tardía. Causada por deficiencia de la enzima propionil-CoA carboxilasa que ocasiona acumulación de ácido propiónico y metabolitos relacionados con propionil-CoA en los tejidos. Es característica la hiperglicinemia, pero puede presentarse hiperlisinemia. Este trabajo describe un caso clínico de AP de inicio neonatal con desenlace fatal y alteración llamativa de los aminoácidos. Caso clínico: Recién nacido (RN) femenina ingresa a unidad neonatal al tercer día de vida por hipoactividad, vómito y letargia. Posterior dificultad respiratoria y realiza paros cardiacos, falleciendo antes de establecer un diagnóstico bioquímico. Paraclínicos iniciales evidenciaron acidosis metabólica, leucopenia, hipoglicemia, posteriormente se documenta hiperglicininemia, hipercistinemia y severa hiperlisininemia. La cromatografía de ácidos orgánicos en orina identificó ácido 3-hidroxi-propionico, metilcitrato y propionilglicina entre otros metabolitos tóxicos, confirmando el diagnóstico. Conclusiones: La AP es un error innato del metabolismo autosómico recesivo de baja incidencia. La presencia de acidosis metabólica severa, pancitopenia, hipoglicemia y antecedentes familiares deben alertar sobre este diagnóstico. Adicionalmente, aunque el diagnóstico bioquímico definitivo son los ácidos orgánicos en orina, la presencia de hiperamonemia, hiperglicinemia e hiperlisinemia pueden ser altamente sugestivas de este trastorno.

ABSTRACT Introduction: Propionic acidemia (AP) is an organic acidemia (AO) with clinical presentation of neonatal onset or late. Caused by deficiency of the enzyme propionil-CoA carboxilasa that causes accumulation of propionic acid and metabolites related to propionyl-CoA in tissues. Hyperglycinemia is characteristic, but hyperlysinemia may occur. This work describes a clinical case of AP of neonatal onset with fatal outcome and striking alteration of amino acids. Clinical case: Female newborn (RN) admitted in the neonatal unit on the third day of life due to hypoactivity, vomiting and lethargy. Subsequent respiratory distress and cardiac arrest occurred, dying before a biochemical diagnosis was established. Initial paraclinics evidenced metabolic acidosis, leukopenia, hypoglycemia, later documented hyperglycinemia, hypercystinemia and severe hyperlysinemia. The organic acid chromatography in urine identified 3-hydroxy-propionic acid, methyl citrate and propionylglycine among other toxic metabolites, confirming the diagnosis. Conclusions: AP is an inborn error of autosomal recessive metabolism of low incidence. The presence of severe metabolic acidosis, pancytopenia, hypoglycemia and family history should alert about this diagnosis. Additionally, although the definitive biochemical diagnosis is organic acids in urine, the presence of hyperammonemia, hyperglycinemia and hyperlysinemia can be highly suggestive of this disorder.

Dos mutaciones novedosas en el gen de glicina descarboxilasa en un niño con hiperglicinemia no cetósica clásica: a propósito de un caso / Two novel mutations in the glycine decarboxylase gene in a boy with classic nonketotic hyperglycinemia: case report

La hiperglicinemia no cetósica es una encefalopatía por glicina autosómica recesiva y hereditaria sumamente rara, causada por una deficiencia en el sistema enzimatico de división de la glicina mitocondrial, que provoca síntomas clínicos graves. La hiperglicinemia no cetósica se caracteriza por fenotipos diversos y complejos, por ejemplo, hipotonía, convulsiones, deterioro cognitivo, retrasos del desarrollo y espasmos mioclónicos que podrían causar apnea e incluso la muerte. En este artículo, presentamos el caso de un niño de 1 año con convulsiones mioclónicas, hipotonía y coma, con aumento de la concentración de glicina en el plasma y el líquido cefalorraquídeo y con un índice de glicina en líquido cefalorraquídeo/plasma de 0,24. Existen dos mutaciones heterocigotas novedosas que confirman el diagnóstico de hiperglicinemia no cetósica. Una es una mutación de aminoácido, c.2516A>G (p.Y839C), y la otra es una mutación en los sitios de corte y empalme, c.2457+2T>A, en el gen GLDC.

Nonketotic hyperglycinemia is an extremely rare autosomal recessively inherited glycine encephalopathy caused by a deficiency in the mitochondrial glycine cleavage system, which leads to severe clinical symptoms. Nonketotic hyperglycinemia is characterized by complex and diverse phenotypes, such as hypotonia, seizures, cognitive impairment, developmental delays and myoclonic jerks that may lead to apnea and even death. Here we report a 1-year-old boy with myoclonic seizures, hypotonia and coma; he had elevated plasma and cerebrospinal fluid glycine levels, and cerebrospinal fluid/plasma glycine ratio was 0.24. Two novel heterozygous mutations confirm the diagnosis of nonketotic hyperglycinemia. One is a missense mutation c.2516A>G (p.Y839C) and the other one is a splicing mutation c.2457+2T>A in the GLDC gene.

Caracterización clínica, bioquímica e imagenológica en una cohorte de pacientes diagnosticados con hiperglicinemia no cetósica clásica: estudio ambispectivo 2000-2014, Medellín, Colombia / Clinical, biochemical and imaging characterization in a cohort of patients diagnosed with classical nonketotic hyperglycinemia: ambispective study 2000-2014, Medellin-Colombia

Introducción: La hiperglicinemia no cetósica (HGNC) es un error innato del metabolismo del grupo de las aminoacidopatías, de carácter autosómico recesivo, causado por un defecto en el sistema de clivaje de la glicina. Es una entidad rara y no se conoce su incidencia en Colombia. Objetivo: Describir características clínicas, bioquímica e imagenológicas en una cohorte de pacientes diagnosticados con hiperglicinemia no cetósica clásica Materiales y métodos: Estudio de tipo descriptivo, ambispectivo, en el periodo enero 2000-2014, en varios centros de Medellín. Resultados: Se incluyeron 20 pacientes que cumplían criterios de inclusión, de los 35 pacientes que cumplían con el criterio de búsqueda, en su mayoría de sexo femenino y con un Apgar adecuado al nacer. El promedio de inicio de los síntomas fue de 2,6 días; somnolencia, hipoactividad, apnea, convulsiones y singulto fueron los principales síntomas, y las convulsiones de tipo focal las más frecuentes. La relación glicina LCR/plasma en promedio fue 0,42. El patrón estallido-supresión en el electroencefalograma y la ausencia o retraso en la mielinización de la sustancia blanca supratentorial en la resonancia magnética fueron hallazgos comunes. Conclusión: La HGNC es frecuente en nuestro medio, por lo cual es necesario que se disponga de pruebas bioquímicas y moleculares necesarias para diagnóstico oportuno, manejo integral y asesoría genética.

Introduction: Nonketotic Hyperglycinemia is an inborn error of metabolism in a group of aminoacidopathies, autosomal recessive, caused by a defect in the system of the glycine cleavage. It is rare, and the incidence is unknown in Colombia. Objective:To describe clinical, biochemical and imaging characteristics in a cohort of patients diagnosed with classical nonketotic hyperglycinemia. Materials and methods: This is a descriptive-ambispective study during the period January 2000 - 2014 in some centers of Medellin. Results: There were 35 patients who met the search criteria and finally 20 patients who met inclusion criteria. We found in this cohort more girls than boys, and most of them with a good APGAR. The average onset of symptoms was 2.6 days, with drowsiness, hypoactivity, apnea, seizures and singultus the main symptoms. The focal seizures were the most frequent type. The average value of CSF glycine to plasma glycine ratio was 0.42. The burst suppression pattern in the EEG and the absence or delayed myelination in the supratentorial white matter on MRI were common findings. All patients received dextromethorphan as part of their treatment and the vast majority of sodium benzoate. Conclusion: HGNC is common in our environment. It´s necessary to have available biochemical and molecular evidence for timely diagnosis, comprehensive management and genetic counseling.

A novel association between cerebral sinovenous thrombosis and nonketotic hyperglycinemia in a neonate / 소아과

Lethargy in newborns usually indicates central nervous system dysfunction, and many conditions such as cerebrovascular events, infections, and metabolic diseases should be considered in the differential diagnosis. Nonketotic hyperglycinemia is an autosomal recessive error of glycine metabolism, characterized by myoclonic jerks, hypotonia, hiccups, apnea, and progressive lethargy that may progress to encephalopathy or even death. Cerebral sinovenous thrombosis is a rare condition with various clinical presentations such as seizures, cerebral edema, lethargy, and encephalopathy. Here, we report the case of a newborn infant who presented with progressive lethargy. An initial diagnosis of cerebral venous sinus thrombosis was followed by confirmation of the presence of nonketotic hyperglycinemia.

Sequential magnetic resonance spectroscopic changes in a patient with nonketotic hyperglycinemia / 소아과

Nonketotic hyperglycinemia (NKH) is a rare inborn error of amino acid metabolism. A defect in the glycine cleavage enzyme system results in highly elevated concentrations of glycine in the plasma, urine, cerebrospinal fluid, and brain, resulting in glycine-induced encephalopathy and neuropathy. The prevalence of NKH in Korea is very low, and no reports of surviving patients are available, given the scarcity and poor prognosis of this disease. In the current study, we present a patient with NKH diagnosed on the basis of clinical features, biochemical profiles, and genetic analysis. Magnetic resonance spectroscopy (MRS) allowed the measurement of absolute glycine concentrations in different parts of the brain that showed a significantly increased glycine peak, consolidating the diagnosis of NKH. In additional, serial MRS follow-up showed changes in the glycine/creatinine ratios in different parts of the brain. In conclusion, MRS is an effective, noninvasive diagnostic tool for NKH that can be used to distinguish this disease from other glycine metabolism disorders. It may also be useful for monitoring NKH treatment.

Early myoclonic encephalopathy.

Early myoclonic encephalopathy (EME) is a rare malignant epileptic syndrome. The erratic myoclonus with or without focal motor seizures, onset before 3 months of age, and persistent suppression-burst pattern in electroencephalograph (EEG) are accepted as the diagnostic criteria for EME. We report an 11 month-old infant with EME which was secondary to non-ketotic hyperglycinemia.

A Case of Korean Patient with Noketotic Hyperglycinemia: Diagnosed Based on CSF Amino Acid Analysis and Magnetic Resonance Spectroscopy

Nonketotic hyperglycinemia is an extremely rare congenital metabolic disorder, which is caused by the lack of a glycine cleavage system. The onset of hyperglycinemic symptom is during the neonatal or early infant period. Progressing grave neuromotor dysfunction is one of the main symptoms. They include myoclonic seizure, hiccup, apnea, decreased deep tendon reflex, lethargy and coma. The prognosis is mostly very poor. Furtherrnore, there aren't any effective treatments for nonketotic hyperglycinemia. To our knowledge, there has been no reported case of nonketotic hyperglycinemia in Korea. We experienced a case of nonketotic hyperglycinemia in a three-day- old boy, who had manifested with intractable seizure, mental alteration, apnea, hiccup and feeding intolerance. Unfortunately, he died of intractable seizure and neuromotor dysfunction at 20 days after birth. We could make an early diagnosis on the basis of clinical suspicion and high glycine signal in both cerebral white matter and basal ganglias with magnetic resonance spectroscopy (MRS), before amino acid analyses of serum and cerebrospinal fluid(CSF) were obtained. We report a Korean case of nonketotic hyperglycinemia with a brief review of literatures.