Two novel compound heterozygous variants of the GCDH gene in two Chinese families with glutaric acidaemia type I identified by high-throughput sequencing and a literature review.

Autosomal recessive glutaric acidaemia type I (GA-I) is a rare hereditary metabolic disease characterized by increased organic acids and neurologic symptoms. Although numerous variants in the GCDH gene have been identified to be connected with the pathogenesis of GA-I, the relationship between genotype and phenotype remains uncertain. In this study, we evaluated genetic data for two GA-I patients from Hubei, China, and we reviewed the previous research findings to clarify the genetic heterogeneity of GA-I and identify the potential causative variants. After we extracted genomic DNA from peripheral blood samples obtained from two unrelated Chinese families, we used target capture high-throughput sequencing combined with Sanger sequencing to determine likely pathogenic variants in the two probands. Electronic databases were also searched for the literature review. The genetic analysis revealed two compound heterozygous variants in the GCDH gene expected to lead to GA-I in the two probands (P1 and P2), with P1 carrying two known variants (c.892G > A/p. A298T and c.1244-2A > C/IVS10-2A > C) and P2 harbouring two novel variants (c.370G > T/p.G124W and c.473A > G/p.E158G). In the literature review, the most common alleles in low excretors (i.e., individuals with low excretion of GA) were R227P, V400M, M405V, and A298T, with variation in the severity of clinical phenotypes. Overall, we identified two novel GCDH gene candidate pathogenic variants in a Chinese patient, enriching the GCDH gene mutational spectrum and providing a solid foundation for the early diagnosis of GA-I patients with low excretion.

Clinical, biochemical and molecular findings of 24 Brazilian patients with glutaric acidemia type 1: 4 novel mutations in the GCDH gene.

Glutaric aciduria type 1 (GA-1) is a rare but treatable inherited disease caused by deficiency of glutaryl-CoA dehydrogenase activity due to GCDH gene mutations. In this study, we report 24 symptomatic GA-1 Brazilian patients, and present their clinical, biochemical, and molecular findings. Patients were diagnosed by high levels of glutaric and/or 3-hydroxyglutaric and glutarylcarnitine. Diagnosis was confirmed by genetic analysis. Most patients had the early-onset severe form of the disease and the main features were neurological deterioration, seizures and dystonia, usually following an episode of metabolic decompensation. Despite the early symptomatology, diagnosis took a long time for most patients. We identified 13 variants in the GCDH gene, four of them were novel: c.91 + 5G > A, c.167T > G, c.257C > T, and c.10A > T. The most common mutation was c.1204C > T (p.R402W). Surprisingly, the second most frequent mutation was the new mutation c.91 + 5G > A (IVS1 ds G-A + 5). Our results allowed a complete characterization of the GA-1 Brazilian patients. Besides, they expand the mutational spectrum of GA-1, with the description of four new mutations. This work reinforces the importance of awareness of GA-1 among doctors in order to allow early diagnosis and treatment in countries like Brazil where the disease has not been included in newborn screening programs.

Molecular and biochemical study of glutaric aciduria type 1 in 49 Russian families: nine novel mutations in the GCDH gene.

Glutaric aciduria type 1 (GA1, deficiency of glutaryl CoA dehydrogenase, glutaric acidemia type 1) (ICD-10 code: E72.3; MIM 231670) is an autosomal recessive disease caused by mutations in the gene encoding the enzyme glutaryl CoA dehydrogenase (GCDH). Herein, we present the biochemical and molecular genetic characteristics of 51 patients diagnosed with GA1 from 49 unrelated families in Russia. We identified a total of 21 variants, 9 of which were novel: c.127 + 1G > T, с.471_473delCGA, c.161 T > C (p.Leu54Pro), c.531C > A (р.Phe177Leu), c.647C > T (p.Ser216Leu), c.705G > A (р.Gly235Asp), c.898 G > A (р.Gly300Ser), c.1205G > C (р.Arg402Pro), c.1178G > A (р.Gly393Glu). The most commonly detected missense variants were c.1204C > T (p.Arg402Trp) and с.1262C > T (р.Ala421Val), which were identified in 56.38% and 11.7% of mutated alleles. A heterozygous microdeletion of the short arm (p) of chromosome 19 from position 12,994,984-13,003,217 (8233 b.p.) and from position 12,991,506-13,003,217 (11,711 b.p.) were detected in two patients. Genes located in the area of imbalance were KLF1, DNASE2, and GCDH. Patients presented typical GA1 biochemical changes in the biological fluids, except one patient with the homozygous mutation p.Val400Met. No correlation was found between the GCDH genotype and glutaric acid (GA) concentration in the cohort of our patients.

Mild phenotype of glutaric aciduria type 1 in polish patients - novel data from a group of 13 cases.

Glutaric aciduria type 1 is a neurometabolic disorder, caused by riboflavin-dependent glutaryl-CoA dehydrogenase deficiency. As its consequence, accumulation of the putatively neurotoxic metabolites (glutaric and 3-hydroxyglutaric acids) in body tissues, but especially within the brain, is observed. Estimated incidence of the disease is 1 in 110,000 newborns, The prevalence however may be higher, depending on a specific ethnic group, and result in phenotypic variation as well. In this paper we present clinical data of 13 patients of Polish nationality. They all present a mild phenotype and clinical course of glutaric aciduria type 1. Based on their clinical data, presented herein, we like to pay attention to the phenotypic and neuroimaging features important for the diagnosis of mild form of this disease. Moreover, we present novel molecular data, which may correlate with such a manifestation.

GAI - distinct genotype and phenotype characteristics in reported Slovak patients.

OBJECTIVES: The clinical, biochemical and genetic findings in two Slovak patients with glutaric aciduria type I (GAI) are presented. BACKGROUND: GAI is a rare autosomal recessive neuro-metabolic disorder caused by deficiency of glutaryl-CoA dehydrogenase, which is involved in the catabolic pathways of lysine, hydroxylysine and tryptophan. This enzymatic defect gives rise to elevated levels of glutaric acid (GA), 3-hydroxyglutaric acid (3-OH-GA) and glutarylcarnitine (C5DC) in body fluids. METHODS: Biochemical and molecular-genetic tests were performed. Urinary organic acids were analysed by Gas Chromatography/Mass Spectrometry (GC/MS) and the entire coding region of the GCDH gene, including flanking parts, was sequenced. RESULTS: We found the presence of typical metabolic profile and novel causal pathogenic variants in both GAI patients. CONCLUSION: We present the first report of two Slovak patients with GAI, which differed in the clinical and biochemical phenotype significantly. They were diagnosed by two distinct approaches - selective and newborn screening. Their diagnosis was complexly confirmed by biochemical and later on molecular-genetic examinations. Though we agreed with a thesis that early diagnostics might positively influenced patient's health outcome, contradictory facts should be considered. Supposed extremely low prevalence of GAI patients in the general population and/or the existence of asymptomatic individuals with a questionable benefit of the applied therapeutic intervention for them lead to doubts whether the inclusion of disease into the newborn screening programme is justified well enough (Tab. 1, Fig. 3, Ref. 41).

Clinical features and GCDH gene variants in three Chinese families with glutaric aciduria type 1: A case series and literature review.

Aim: To analyze the clinical phenotype and genetic etiology of three cases of glutaric aciduria type 1 (GA1) in Chinese children. Methods: We performed genetic and metabolic testing using tandem mass spectrometry (MS/MS) and gas chromatography-mass spectrometry (GC/MS), followed by trio whole-exome sequencing (trio-WES) and Sanger sequencing. A literature review on glutaric aciduria type 1 (GA1) in Chinese patients was also conducted. Results: Sequencing results showed each case had compound heterozygous variants in GCDH(NM_000159.4): c.214C > G (p.Arg72Gly) and c.411C > G (p.Tyr137Term) (Case 1), c.214C > G (p.Arg72Gly) and c.1204C > T (p.Arg402Trp) (Case 2), and c.1228G > T (p.Val410Leu) and c.395G > A (p.Arg132Gln) (Case 3). These variants were inherited from their respective parents. Notably, the c.214C > G variant found in two children was a novel variant not previously reported. A review of the literature revealed that, clinically, the majority of patients experienced onset in infancy and early childhood (82%). Additionally, 38.36% were diagnosed through newborn screening, with the primary reasons for the initial visit being delayed development (32.43%) and infections (21.61%). The most common clinical manifestations included increased head circumference (77.19%) and motor developmental delay (65.15%). Biochemically, patients exhibited significant elevations in C5DC (98.51%) and C5DC/C8 (94.87%) in blood, as well as GA (94.37%) and 3OHGA (69.39%) in urine. Radiographically, patients showed a high prevalence of abnormalities in cranial MRI (86.15%) and EEG (73.33%). Genetically, 67 distinct GCDH gene variants were identified among 73 patients, with missense variants being the most prevalent type (73.97%). The most frequent variant was c.1244-2 A > C, observed in 17.12% of cases. Additionally, the majority of variant sites were located in exons 11 (25.37%) and 6 (22.39%). Conclusion: GCDH variants were identified as the causative factors in the three children. The discovery of the novel variant (c.214C > G) expands the spectrum of pathogenic GCDH variants. These findings facilitate the diagnosis and treatment of affected children and provide a basis for genetic counseling and prenatal diagnosis for their families.

Biochemical, molecular, and clinical features of patients with glutaric acidemia type 1 identified through large-scale newborn screening in Zhejiang Province, China.

BACKGROUND: Glutaric acidemia type 1 (GA1) is a treatable neurometabolic disorder caused by biallelic variants in the glutaryl-CoA dehydrogenase (GCDH) gene. There are few large-scale reports describing newborn screening (NBS) for GA1 in China. We report the NBS results, genotypes, and clinical features of patients diagnosed through NBS. METHODS: From January 2009 to August 2021, 4,202,587 newborns were screened by tandem mass spectrometry. Newborns with increased glutarylcarnitine (C5DC) concentrations were recalled for repeated test, and confirmatory examinations were performed if the second test was still positive. The pathogenicity of novel variants was predicted using computational programs. RESULTS: A total of 693 had increased C5DC concentrations, and 19 patients were diagnosed with GA1. Thus, the estimated incidence of GA1 in Zhejiang Province was 1 in 221,053 newborns. All the 19 patients had markedly increased C5DC concentrations and C5DC/octanoylcarnitine (C8) ratios; one had a slightly low free carnitine concentration. Seventeen (17/18, 94.4%) patients had increased GA concentrations, 15 were of high excretor phenotype and 3 were of low excretor phenotype. Twenty-three distinct GCDH variants were detected, of which 2were novel. Novel variants were predicted to be potentially pathogenic by computational programs. c.1244-2A > C was the most common variant, with an allelic frequency of 14.7%, followed by c.914C > T (p.S305L) (8.8%). The most common clinical symptom was movement disorder, followed by seizure, macrocephaly, and failure to thrive. Sylvian fissures widening was the most common MRI finding. CONCLUSIONS: Nineteen GA1 patients were diagnosed through the large-scale NBS in Zhejiang Province, with an estimated incidence of 1 in 221,053 newborns. The GCDH mutational spectrum is heterogenous, with the c.1244-2A > C variant being the most frequent variant in this population. NBS for GA1 should be promoted to achieve timely diagnosis and treatment.

Evaluation of the Clinical, Biochemical, Neurological, and Genetic Presentations of Glutaric Aciduria Type 1 in Patients From China.

PURPOSE: To characterize the phenotypic and genotypic variations associated with Glutaric aciduria type 1 (GA1) in Chinese patients. METHODS: We analyzed the clinical, neuroradiological, biochemical, and genetic information from 101 GA1 patients in mainland China. RESULTS: 20 patients were diagnosed by newborn screening and the remaining 81 cases were identified following clinical intervention. Macrocephaly was the most common presentation, followed by movement disorders and seizures. A total of 59 patients were evaluated by brain MRI and 58 patients presented with abnormalities, with widening of the sylvian fissures being the most common symptom. The concentration of glutarylcarnitine in the blood, glutarylcarnitine/capryloylcarnitine ratio, and urine levels of glutaric acid were increased in GA1 patients and were shown to decrease following intervention. A total of 88 patient samples were available for genotyping and 74 variants within the GCDH gene, including 23 novel variants, were identified. The most common variant was c.1244-2A > C (18.4%) and there were no significant differences in the biochemical or clinical phenotypes described for patients with the four most common variants: c.1244-2A > C, c.1064G > A, c.533G > A, and c.1147C > T. Patients identified by newborn screening had better outcomes than clinical patients. CONCLUSION: Our findings expand the spectrum of phenotypes and genotypes for GA1 in Chinese populations and suggest that an expanded newborn screening program using tandem mass spectrometry may facilitate the early diagnosis and treatment of this disease, improving clinical outcomes for patients in China.

Siblings with Glutaric Aciduria Type 1 with Atypical Phenotype with Novel Pathogenic Variant in GCDH Gene.

Glutaric aciduria type 1 (GA1) is caused by a deficiency of the enzyme glutaryl CoA dehydrogenase. It generally presents with developmental delay, dystonia, and large head. We are reporting siblings of GA1, presenting with an atypical phenotype with novel pathogenic variant. Thirteen-year-old boy presented with global developmental delay and stiffness of limbs. Examination revealed normocephaly and generalized dystonia. MRI T2WI was suggestive of symmetrical posterior putaminal atrophy. Tandem mass spectroscopy (TMS) and urinary gas chromatography-mass spectrometry (GCMS) were normal. Genetic analysis revealed a novel pathogenic homozygous missense variant in GCDH gene. An 8-year-old girl younger sibling of above child also had developmental delay and dystonia, posterior putamen atrophy in the MRI of brain, and same pathogenic variant in GCDH gene. Parents screening showed heterozygous status in both parents of same pathogenic variant. Any child who presents with global developmental delay with dystonia even with normocephaly, isolated symmetrical posterior putamen changes, with normal TMS and GCMS, a possibility of glutaric aciduria type 1 has to be considered.

Biochemical and molecular features of Chinese patients with glutaric acidemia type 1 detected through newborn screening.

BACKGROUND: Glutaric acidemia type 1 (GA1) is a treatable disorder affecting cerebral organic acid metabolism caused by a defective glutaryl-CoA dehydrogenase (GCDH) gene. GA1 diagnosis reports following newborn screening (NBS) are scarce in the Chinese population. This study aimed to assess the acylcarnitine profiles and genetic characteristics of patients with GA1 identified through NBS. RESULTS: From January 2014 to September 2020, 517,484 newborns were screened by tandem mass spectrometry, 102 newborns with elevated glutarylcarnitine (C5DC) levels were called back. Thirteen patients were diagnosed with GA1, including 11 neonatal GA1 and two maternal GA1 patients. The incidence of GA1 in the Quanzhou region was estimated at 1 in 47,044 newborns. The initial NBS results showed that all but one of the patients had moderate to markedly increased C5DC levels. Notably, one neonatal patient with low free carnitine (C0) level suggest primary carnitine deficiency (PCD) but was ultimately diagnosed as GA1. Nine neonatal GA1 patients underwent urinary organic acid analyses: eight had elevated GA and 3HGA levels, and one was reported to be within the normal range. Ten distinct GCDH variants were identified. Eight were previously reported, and two were newly identified. In silico prediction tools and protein modeling analyses suggested that the newly identified variants were potentially pathogenic. The most common variant was c.1244-2 A>C, which had an allelic frequency of 54.55% (12/22), followed by c.1261G>A (p.Ala421Thr) at 9.09% (2/22). CONCLUSIONS: Neonatal GA1 patients with increased C5DC levels can be identified through NBS. Maternal GA1 patients can also be detected using NBS due to the low C0 levels in their infants. Few neonatal GA1 patients may have atypical acylcarnitine profiles that are easy to miss during NBS; therefore, multigene panel testing should be performed in newborns with low C0 levels. This study indicates that the GCDH variant spectra were heterogeneous in this southern Chinese cohort.

Glutaric Aciduria Type I Missed by Newborn Screening: Report of Four Cases from Three Families.

Glutaric aciduria type I (GA-1) is a rare autosomal-recessive disorder of the degradation of the amino acids lysine and tryptophan caused by mutations of the GCDH gene encoding glutaryl-CoA-dehydrogenase. Newborn screening (NBS) for this condition is based on elevated levels of glutarylcarnitine (C5DC) in dried blood spots (DBS). Here we report four cases from three families in whom a correctly performed NBS did not detect the condition. Glutarylcarnitine concentrations were either normal (slightly below) or slightly above the cut-off. Ratios to other acylcarnitines were also not persistently elevated. Therefore, three cases were defined as screen negative, and one case was defined as normal, after a normal control DBS sample. One patient was diagnosed after an acute encephalopathic crisis, and the other three patients had an insidious onset of the disease. GA-1 was genetically confirmed in all cases. Despite extensive efforts to increase sensitivity and specificity of NBS for GA-1, by adjusting cut-offs and introducing various ratios, the biological diversity still leads to false-negative NBS results for GA-1.

Glutaric Acidemia Type 1: A Case of Infantile Stroke.

BACKGROUND: Glutaric acidemia Type 1 (GA-1) is an autosomal recessively inherited metabolic disorder which is associated with GCDH gene mutations which alters the glutaryl-CoA dehydrogenase, an enzyme playing role in the catabolic pathways of the amino acids lysine, hydroxylysine, and tryptophan. Clinical findings are often encephalopathic crises, dystonia, and extrapyramidal symptoms. CASE REPORT: A 9-month-old male infant referred to our department with focal tonic-clonic seizures during rotavirus infection and acute infarcts in MRI. Clinical manifestation, MRI findings, and metabolic investigations directed thoughts towards GA-I. Molecular genetic testing revealed a homozygous c.572T>C (p.M191T) mutation in GCDH gene which confirmed the diagnosis. Application of protein restricted diet, carnitine and riboflavin supplementations prevented the progression of Magnetic Resonance Imaging (MRI) and clinical pathologic findings during the 1 year of follow-up period. CONCLUSION: This case is of great importance since it shows possibility of infantile stroke in GA-1, significance of early diagnosis and phenotypic variability of disease.

Prenatal diagnosis of fetal glutaric aciduria type 1 with rare compound heterozygous mutations in GCDH gene.

OBJECTIVE: Glutaric aciduria type 1 is a rare disease, with the estimated prevalence about 1 in 100,000 newborns. GCDH gene mutation can lead to glutaric acid and 3- OH glutaric acid accumulation, with clinical manifestation of neuronal damage, brain atrophy, microencephalic macrocephaly, decreased coordination of swallowing, poor muscle coordination, spasticity, and severe dystonic movement disorder. CASE REPORT: A 22-year-old female, Gravida 4 Para 2, is pregnancy at 13 weeks of gestational age. Her first child is normal, however, the second child was diagnosed as glutaric aciduria type I after birth. She came to our hospital for prenatal genetic counselling of her fetus at 13 weeks of gestational age. We performed GCDH gene mutation analysis of maternal blood showed IVS 3 + 1 G > A heterozygous mutation, GCDH gene mutation analysis of paternal blood showed c. 1240 G > A heterozygous mutation, and the second child has compound heterozygous IVS 3 + 1 G > A and c. 1240 G > A mutations. Later, we performed amniocentesis at 16 weeks of gestational age for chromosome study and GCDH gene mutation analysis for the fetus. The fetal chromosome study showed normal karyotype, however, GCDH gene mutation analysis showed compound heterozygous IVS 3 + 1 G > A and c. 1240 G > A mutations. The couple decided to termination of pregnancy thereafter. CONCLUSION: Glutaric acidemia type 1 is an autosomal recessive disorder because of pathogenic mutations in the GCDH gene. Early diagnosis and therapy of glutaric acidemia type 1 can reduce the risk of neuronal damage and acute dystonia. We report a case of prenatal diagnosis of fetal glutaric aciduria type 1 with rare compound heterozygous GCDH gene mutation at IVS 3 + 1 G > A and c. 1240 G > A mutations, which provide better genetic counselling for the couples.

Clinical and laboratory analysis of late-onset glutaric aciduria type I (GA-I) in Uighur: A report of two cases.

The aim of the present study was to investigate the clinical, biochemical and genetic mutation characteristics of two cases of late-onset glutaric aciduria type I (GA-I) in Uighur. The clinical data and glutaryl-CoA dehydrogenase (GCDH) genetic test results of two cases of late-onset GA-I in Uighur were collected and analyzed, and reviewed with relevant literature. One patient with late-onset GA-I primarily exhibited clinical intermittent headache, while the other patient was asymptomatic. The urinary organic acid analysis detected a large number of glutaric acid and 3-hydroxy glutaric acid, 3-hydroxy-propionic acid. One patient exhibited white matter degeneration in cranial magnetic resonance imaging (MRI) and the other patient showed no abnormality. The two patients both exhibited c. 1204C >T, p.R402W, heterozygous mutation, and c. 532G >A, p.G178R, heterozygous mutation. Besides central nervous system infectious diseases, patients with clinical headache, cranial MRI-suggested bilateral temporal lobe arachnoid cyst and abnormal signals in the basal ganglia should be highly suspected as late-onset GA-I. Early diagnosis and correct treatment are key to improve its prognosis.