Two Novel GLDC Mutations in a Neonate with Nonketotic Hyperglycinemia.
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ABSTRACT:
SUBMITTER: Nickerson SL
PROVIDER: S-EPMC4999328 | biostudies-literature | 2016 Sep
REPOSITORIES: biostudies-literature
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Two Novel GLDC Mutations in a Neonate with Nonketotic Hyperglycinemia.
Nickerson Sarah L SL Balasubramaniam Shanti S Dryland Philippa A PA Love Jennifer M JM Kava Maina P MP Love Donald R DR Prosser Debra O DO
Journal of pediatric genetics 20160615 3
Nonketotic hyperglycinemia, also known as glycine encephalopathy (OMIM #605899), is an autosomal recessive disorder of glycine metabolism resulting from a defect in the glycine cleavage system. We report two novel mutations of the glycine decarboxylase (GLDC) gene observed in a compound heterozygous state in a neonate of mixed Maori and Caucasian parentage: c.395C>T p.(Ser132Leu) in exon 3, and c.256-?_334+?del p.(Ser86Valfs*119), resulting in an out-of-frame deletion of exon 2. Additionally, we ...[more]
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Project description:Nonketotic hyperglycinemia (NKH) is an autosomal recessive hereditary disease caused by a defect in the glycine cleavage system and is classified into typical and atypical NKH. Atypical NKH has complex manifestations and is difficult to diagnose in clinical practice. This article reports a family of NKH. The parents had normal phenotypes, and the older brother and the younger sister developed this disease in the neonatal period. The older brother manifested as intractable epilepsy, severe spastic diplegia, intellectual disability, an increased level of glycine in blood and cerebrospinal fluid, an increased glycine/creatinine ratio in urine, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. The younger sister manifested as delayed language development, ataxia, chorea, mental and behavior disorders induced by pyrexia, hypotonia, an increased level of glycine in cerebrospinal fluid, and an increased ratio of glycine concentration in cerebrospinal fluid and blood. High-throughput sequencing found a maternal missense mutation, c.3006C>G (p.C1002W), and a paternal nonsense mutation, c.1256C>G (p.S419X), in the GLDC gene in both patients. These two mutations were thought to be pathogenic mutations by a biological software. H293T cells transfected with these two mutants of the GLDC gene had a down-regulated activity of glycine decarboxylase. NKH has various phenotypes, and high-throughput sequencing helps to make a confirmed diagnosis. Atypical NKH is associated with the downregulated activity of glycine decarboxylase caused by gene mutations.
| S-EPMC7389275 | biostudies-literature
Project description:PurposeNeonatal nonketotic hyperglycinemia is an autosomal recessive inborn disorder of glycine metabolism in which large quantities of glycine accumulate in all body tissues. It is characterized by a progressive lethargy, hypotonia, myoclonic jerks, and early death secondary to respiratory problems. As a result of early diagnosis and treatment protocols, more patients survive the critical neonatal period with profound mental retardation, delayed developmental milestones, seizures, and spasticity. There are no reports about the orthopaedic manifestations of neonatal nonketotic hyperglycinemia. The purpose of this study is to evaluate the musculoskeletal findings of neonatal nonketotic hyperglycinemia.MethodsThis is a retrospective IRB-approved study of all patients in our Orthopaedic and Genetics Clinics with the diagnosis of neonatal nonketotic hyperglycinemia during a 10-year period. Demographic, clinical, and imaging data were analyzed.ResultsTwelve patients with neonatal nonketotic hyperglycinemia were evaluated, with a mean age of 7 years and 2 months (range: 5 months to 21 years). Seven were male and five were female. Eleven patients (92 %) have evidence of progressive early-onset neuromuscular scoliosis with a mean Cobb angle of 55° (range: 30-95°). Five children (42 %) presented evidence of progressive hip dislocation secondary to spasticity. All the patients have severe multiple joint contractures.ConclusionNeonatal nonketotic hyperglycinemia is a rare metabolic disorder presented in the past as a lethal condition. Recent advances in early diagnosis and neonatal care improve overall outcome. As pediatric orthopaedic surgeons, we need to establish treatment based on update information of the disease and probability to improve quality of life.
| S-EPMC3400000 | biostudies-literature
Project description:Nonketotic hyperglycinemia (NKH) is in most cases a fatal inborn error of metabolism which usually presents during the neonatal period as encephalopathy and refractory seizures. The reported congenital anomalies associated with NKH included corpus callosal agenesis, club foot, cleft palate, and congenital heart disease. Here, we report a newborn who presented with encephalopathy without overt seizures, cerebral venous sinus thrombosis, and cleft palate. Electroencephalography showed a burst suppression pattern, which suggests the etiology could be due to a metabolic or genetic disorder. The amino acid analysis of plasma and cerebrospinal fluid showed elevated glycine. Whole exome sequencing identified a heterozygous c.492C > G; p.Tyr164Ter variant in exon 4 of the GLDC gene inherited from the patient's father. Further long-read whole genome sequencing revealed an exon 1-2 deletion in the GLDC gene inherited from the patient's mother. Additional analyses revealed no pathogenic variants of the cleft palate-related genes. The cleft palate may be an associated congenital anomaly in NKH. Regarding cerebral venous sinus thrombosis, we found a heterozygous variant (p.Arg189Trp) of the PROC gene, which is a common cause of thrombophilia among Thai newborns. A neonate with NKH could present with severe encephalopathy without seizures. A close follow up for clinical changes and further next generation sequencing are crucial for definite diagnosis in neonates with encephalopathy of unclear cause.
| S-EPMC10442541 | biostudies-literature
Project description: Not available
| S-EPMC7390138 | biostudies-literature
Project description:ObjectiveNonketotic hyperglycinemia is a neurometabolic disorder characterized by intellectual disability, seizures, and spasticity. Patients with attenuated nonketotic hyperglycinemia make variable developmental progress. Predictive factors have not been systematically assessed.MethodsWe reviewed 124 patients stratified by developmental outcome for biochemical and molecular predictive factors. Missense mutations were expressed to quantify residual activity using a new assay.ResultsPatients with severe nonketotic hyperglycinemia required multiple anticonvulsants, whereas patients with developmental quotient (DQ) > 30 did not require anticonvulsants. Brain malformations occurred mainly in patients with severe nonketotic hyperglycinemia (71%) but rarely in patients with attenuated nonketotic hyperglycinemia (7.5%). Neonatal presentation did not correlate with outcome, but age at onset ≥ 4 months was associated with attenuated nonketotic hyperglycinemia. Cerebrospinal fluid (CSF) glycine levels and CSF:plasma glycine ratio correlated inversely with DQ; CSF glycine > 230 μM indicated severe outcome and CSF:plasma glycine ratio ≤ 0.08 predicted attenuated outcome. The glycine index correlated strongly with outcome. Molecular analysis identified 99% of mutant alleles, including 96 novel mutations. Mutations near the active cleft of the P-protein maintained stable protein levels. Presence of 1 mutation with residual activity was necessary but not sufficient for attenuated outcome; 2 such mutations conferred best outcome. Divergent outcomes for the same genotype indicate a contribution of other genetic or nongenetic factors.InterpretationAccurate prediction of outcome is possible in most patients. A combination of 4 factors available neonatally predicted 78% of severe and 49% of attenuated patients, and a score based on mutation severity predicted outcome with 70% sensitivity and 97% specificity.
| S-EPMC4767401 | biostudies-literature
Project description:BackgroundNonketotic hyperglycinemia (NKH) is a rare autosomal recessive genetic disorder of abnormal glycine metabolism caused by insufficient activity of the glycine cleavage enzyme system. Glycine is believed to function mainly as an inhibitory neurotransmitter, but it can also act as a co-agonist of the N-methyl-D-aspartate (NMDA) receptor. The accumulation of a large amount of glycine in the brain leads to neuronal and axonal injury via overactivation of NMDA receptors located in the hippocampus, cerebral cortex, olfactory bulb, and cerebellum and to stimulation of the inhibitory function of glycine receptors located in the spinal cord and brain stem, resulting in central apnea, hiccups, and hypotonia in the early stage of the disease.Case summaryThe child described in this report had typical clinical manifestations of NKH, such as hiccups, disturbance of consciousness, hypotonia, and convulsions, within the first week after birth. Whole-exome genetic testing revealed that the child had a compound heterozygous mutation, namely, c.395C>A (p.S132X) and c.2182G>A (p.G728R), in the GLDC gene, and he was diagnosed with NKH. For treatment, we administered an oral levetiracetam solution and added topiramate and prednisone for epilepsy control, but the epilepsy remained uncontrollable. Ketogenic diet therapy was started at 6 mo of age, his seizures were significantly reduced, and there were no obvious adverse reactions during ketogenic treatment. Furthermore, we found that with the development of the disease, high levels of serum glycine decreased or even disappeared without intervention, and as the disease progressed, the corpus callosum became dysplastic.ConclusionThis case shows that plasma glycine levels cannot be used to evaluate the prognosis of NKH, that the development of the corpus callosum can be affected by NKH, and that a ketogenic diet may be effective for seizure control in NKH patients.
| S-EPMC9372859 | biostudies-literature
Project description:Glycine encephalopathy (GE), also known as nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder due to a primary defect in the glycine cleavage enzyme system. It is characterized by elevated levels of glycine in the plasma and cerebrospinal fluid (CSF) and increased CSF to plasma glycine ratio. Mutations in three genes of the mitochondrial glycine cleavage system have been found to cause NKH. Most patients have a mutation in the GLDC . In this report, we present five new patients from Middle Eastern families with NKH. They were all born to consanguineous parents and two of them have family history of similarly affected sibling(s). All patients presented with neonatal encephalopathy associated with seizures. Their diagnoses were suspected clinically and confirmed biochemically. DNA sequence analysis of the five patients revealed five different pathogenic or likely pathogenic variants in the GLDC . Three were missense variants (c.2675C > T; p.Ala892Val), (c.2512A > G; p.Asn838Asp), and (c.2943A > C; p.Lys981Asn); one was an intronic missense variant (c.1402-2A > T) leading to an exonic deletion, and one was a deletion of 42 amino acids (c.1927-?_2052 + ?del.) All variants were novel and homozygous. The pathogenicity of these variants was determined according to the American College of Medical Genetics (ACMG) variant classification and in silico analysis. Another novel homozygous variant (c.1384C > G; p.Leu462Val) was detected, which was classified as likely benign. The novel variants identified in the GLDC in these patients underlie the pathogenesis of NKH, specifically for the Middle Eastern population. This expands the mutation spectrum of NKH to include a distinct ethnic population that has not been studied before.
| S-EPMC9848757 | biostudies-literature
Project description:Nonketotic hyperglycinemia (NKH) is caused by deficient glycine cleavage enzyme activity and characterized by elevated brain glycine. Metabolism of glycine is connected enzymatically to serine through serine hydroxymethyltransferase and shares transporters with serine and threonine. We aimed to evaluate changes in serine and threonine in NKH patients, and relate this to clinical outcome severity. Age-related reference values were developed for cerebrospinal fluid (CSF) serine and threonine from 274 controls, and in a cross-sectional study compared to 61 genetically proven NKH patients, categorized according to outcome. CSF d-serine and l-serine levels were stereoselectively determined in seven NKH patients and compared to 29 age-matched controls. In addition to elevated CSF glycine, NKH patients had significantly decreased levels of CSF serine and increased levels of CSF threonine, even after age-adjustment. The CSF serine/threonine ratio discriminated between NKH patients and controls. The CSF glycine/serine aided in discrimination between severe and attenuated neonates with NKH. Over all ages, the CSF glycine, serine and threonine had moderate to fair correlation with outcome classes. After age-adjustment, only the CSF glycine level provided good discrimination between outcome classes. In untreated patients, d-serine was more reduced than l-serine, with a decreased d/l-serine ratio, indicating a specific impact on d-serine metabolism. We conclude that in NKH the elevation of glycine is accompanied by changes in l-serine, d-serine and threonine, likely reflecting a perturbation of the serine shuttle and metabolism, and of one-carbon metabolism. This provides additional guidance on diagnosis and prognosis, and opens new therapeutic avenues to be explored.
| S-EPMC9543955 | biostudies-literature
Project description:BackgroundNon-ketotic hyperglycinemia (NKH) is a rare, devastating autosomal recessive disorder of glycine metabolism with a very poor prognosis. Currently, few studies have reported genetic profiling of Chinese NKH patients. This study aimed to identify the genetic mutations in a Chinese family with NKH.MethodsA Chinese family of Han ethnicity, with three siblings with NKH was studied. Sanger sequencing and multiplex ligation-dependent probe amplification combined with SYBR green real-time quantitative PCR was used to identify potential mutations in the GLDC, AMT and GCSH genes. The potential pathogenicity of the identified missense mutation was analyzed using SIFT, PolyPhen-2, PROVEAN and MutationTaster software.ResultsAll patients exhibited severe and progressive clinical symptoms, including lethargy, hypotonia and seizures, and had greatly elevated glycine levels in their plasma and CSF. Molecular genetic analysis identified compound heterozygous variants in the GLDC gene in these three siblings, including a novel missense variant c.2680A > G (p.Thr894Ala) in exon 23 and a heterozygous deletion of exon 3, which were inherited respectively from their parents. In silico analysis, using several different types of bioinformatic software, predicted that the novel variant c.2680A > G in the GLDC gene was pathogenic. Moreover, the deletion of exon 3 was identified for the first time in a Chinese population.ConclusionsA novel missense variant and a previously reported deletion in GLDC gene were identified. The two variants of GLDC gene identified probably underlie the pathogenesis of non-ketotic hyperglycinemia in this family, and also enrich the mutational spectrum of GLDC gene.
| S-EPMC5755286 | biostudies-literature
Project description:Nonketotic hyperglycinemia (NKH) is a rare, inborn error of metabolism. In this case report, a Chinese male infant was diagnosed with NKH caused by GLDC gene mutation. The clinical characteristics and genetic diagnosis were reported. The infant presented with an onset of early metabolic encephalopathy and Ohtahara syndrome. Both blood and urinary levels of metabolites were in the normal range. Brain MRI images indicated a poor development of corpus callosum, and a burst suppression pattern was found in the EEG. Results of target gene sequencing technology combined with multiplex ligation-dependent probe amplification (MLPA) indicated a heterozygous missense mutation of c.1786 C>T (p.R596X) in maternal exon 15 and a loss of heterozygosity of 4-15 exon gross deletions in paternal GLDC gene. These definite pathogenic mutations confirmed the diagnosis of NKH. The infant's clinical condition was not improved after treatment with adreno-cortico-tropic-hormone, topiramate and dextromethorphan, and he finally died at 4 months of age. Patients with NKH often exhibit complicated clinical phenotypes and are lack of specific symptoms. NKH could be diagnosed by metabolic screening and molecular genetic analysis.
| S-EPMC7390153 | biostudies-literature