Glutaric Aciduria Type I Patients Research Articles

Glutaric aciduria and L-2-hydroxyglutaric aciduria: Clinical and molecular findings of 35 patients from Turkey

BackgroundCerebral organic acid disorders are progressive neurometabolic diseases characterized by neurologic dysfunction. Glutaric aciduria type I (GA-I) and L-2-hydroxyglutaric aciduria (L2HGA) are the main cerebral organic acid disorders. They are both classified as, and it is suggested that these two disorders may share a common metabolic pathway. Current treatment strategies are based on levocarnitine, vitamin B2, and diet. Recent guidelines recommend a lysine-restricted diet up to six years of age, but there is no consensus for patients over the age of six. Vitamin B2 is exists in the blood as riboflavin and its cofactors, flavin mononucleotide and flavin adenine dinucleotide (FAD). FAD, the cofactor of L2HGD, accelerates the conversion of L-2-hydoxy glutarate to alpha-ketoglutarate. Levocarnitine stimulates the formation and excretion of derivatives of glutaric acid. Also, lysine-associated organic acidurias some results provide principal proof for the beneficial effects of riboflavin in GA-I. It has been previously reported that combination therapy with riboflavin and levocarnitine is effective for L2HGA as well as GA-I. Riboflavin and levocarnitine have been reported to improve not only clinical symptoms but also urinary 2-HGA levels. In our study, we aimed to evaluate the effect of the current treatment strategies and genotype on urinary metabolites and IQ scores in GA-I and L2HGA patients. MethodsThe presented retrospective multicenter study included patients followed up in Diyarbakir Children's Hospital and Izmir Katip Celebi University Faculty of Medicine, Division of Pediatric Metabolism. Between 2016 and 2021, we retrospectively evaluated 35 patients with confirmed diagnosis of GA-I and L-2HGA. We analyzed the clinical, biochemical, neuroradiological, molecular data and treatment of the patients. The follow-up period was every 2 months until 12 months old, every 3 months until 6 years of age, and every 6 months thereafter. Therapy monitoring was undertaken during follow-up visits that included evaluation of clinical parameters, laboratory parameters, and dietary consumption records. Denver II was applied in order to evaluate children aged 0–6 years in terms of development. Patients between 6 and 16 years of age were evaluated using the Wechsler Intelligence Scale for Children-Revised. ResultsWe identified 25 with GA-I and 10 with L2HGA. The most common clinical symptoms were developmental delay, intellectual disability, and movement disorders. Behavioural problems were more common in L2HGA than in GA-I patients. In the same family, there were patients with severe developmental delay despite early diagnosis and treatment and individuals with normal IQ scores. In our study group, we used diet (lysine restricted or protein controlled), levocarnitine and vitamin B2 for GA-I patients. The mean urinary glutaric acid levels were decreased with treatment in GA-I patients. Group I consisted of 14/25 patients receiving lysine restricted diet and levocarnitine, Group II (8/25) received protein-controlled diet and levocarnitine. Group III (3/25) patients whom had p.Pro248Leu (P248L) variant, received riboflavin in combination with protein-controlled diet and levocarnitine. When we evaluated according to the treatment groups, a significant decrease was observed in urinary glutaric acid levels in group I. But there were no significant difference in Group II and III. The patients with c.1018C > T variant in GCDH gene had higher pre-treatment urinary metabolites and significant reduction in urinary metabolites with treatment was detected. In L2HGA patients, we used levocarnitine and vitamin B2. In all L2HGA patients, there was a significant decrease in the mean urinary 2- hydoxy glutarate with treatment. However, there was no significant difference between the c.164G > A and c.1115delT variants. The mean pre- and post-treatment IQ scores of GA-I patients, no significant difference was observed. Relative neurologic improvement was seen in three L2HGA patients. We found two novel variants, including the c.221A > G (p.Tyr74Cys) in the GCDH gene and the c.738 + 5A > G splice variant in the L2HGDH gene. ConclusionsGlutaric aciduria type I and L2HGA are the most common cerebral organic acidurias. Early and correct diagnosis is crucial. Poor prognosis based on metabolic crises and progressive deterioration still appears. In countries where newborn screening is not performed, a clinical suspicion index is required for cerebral organic aciduria. GA-I and L-2HGA are difficult to examine by medical evidence standards because of the small sample size, regional differences in newborn screening, and medical care limits. More clinical studies are needed to identify effective treatments. However, the significant decrease in urinary glutaric acid levels after treatment in patients on lysine-restricted diet raises the question of whether lysine-restricted diet should be continued after six years of age. We also reported our experience in order to contribute to the literature.

Molecular identification of glutaryl CoA dehydrogenase gene variations and clinical course in three glutaric aciduria type I patients

Glutaric aciduria type-I (GA-I) is a rare autosomal recessive organic-aciduria caused due to glutaryl-CoA-dehydrogenase (GCDH) gene mutations leading to the accumulation of neurotoxins. In this article, we describe the molecular study of three GA-I families from southern India. Clinical features and biochemical parameters were examined. DNA was isolated from dried blood spots and GCDH gene analysis was performed using polymerase chain reaction and Sangers sequencing. Computational assessment of the mutations was performed to analyse their pathogenicity. Median age of the patients was 8 months and parental consanguinity was seen in all the three families. All GA-I patients had a mild clinical course, with brain atrophies. Macrocephaly was not noted. Mutation analysis identified three likely pathogenic mutations including two novel GCDH gene variants (S189T and W225S) and one previously reported variant (R386P). In-silico tools determined R386P and W225S mutations to be deleterious, while S189T to be neutral to the GCDH protein. The S189T was associated with a low excretor phenotype. In conclusion, identification of mutations by genotyping tests in distinct populations can accomplish early DNA based GA-I screening and is useful in definitive diagnosis of GA-I without the prior need of biochemical or enzyme assay.

Functional Recovery of a GCDH Variant Associated to Severe Deflavinylation-Molecular Insights into Potential Beneficial Effects of Riboflavin Supplementation in Glutaric Aciduria-Type I Patients.

Riboflavin is the biological precursor of two important flavin cofactors—flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN)—that are critical prosthetic groups in several redox enzymes. While dietary supplementation with riboflavin is a recognized support therapy in several inborn errors of metabolism, it has yet unproven benefits in several other pathologies affecting flavoproteins. This is the case for glutaric aciduria type I (GA-I), a rare neurometabolic disorder associated with mutations in the GCDH gene, which encodes for glutaryl-coenzyme A (CoA) dehydrogenase (GCDH). Although there are a few reported clinical cases that have responded to riboflavin intake, there is still not enough molecular evidence supporting therapeutic recommendation. Hence, it is necessary to elucidate the molecular basis in favor of riboflavin supplementation in GA-I patients. Here, using a combination of biochemical and biophysical methodologies, we investigate the clinical variant GCDH-p.Val400Met as a model for a phenotype associated with severe deflavinylation. Through a systematic analysis, we establish that recombinant human GCDH-p.Val400Met is expressed in a nonfunctional apo form, which is mainly monomeric rather than tetrameric. However, we show that exogenous FAD is a driver for structural reorganization of the mutant enzyme with concomitant functional recovery, improved thermolability, and resistance to trypsin digestion. Overall, these results establish proof of principle for the beneficial effects of riboflavin supplementation in GA-I patients.

Mutational analysis of glutaryl CoA dehydrogenase gene in glutaric aciduria type-I patients: A study from India

Mutational analysis of glutaryl CoA dehydrogenase gene in glutaric aciduria type-I patients: A study from India

Is Expanded Newborn Screening Adequate to Detect Indian Biochemical Low Excretor Phenotype Patients of Glutaric Aciduria Type I?

To investigate if expanded newborn screening using tandem mass spectroscopy (TMS) is adequate to detect low excretor phenotype in Indian Glutaric aciduria type I (GA-I) patients. Ten GA-I patients were investigated for blood glutaryl carnitine (C5DC) levels on dried blood spot (DBS) by tandem mass spectroscopy and urine glutaric acid (GA) and 3-hydroxyglutaric acid (3-OH-GA) by gas chromatography-mass spectroscopy. The student's T test and Pearson's correlation were applied to draw a relationship between various biochemical parameters. Further confirmation of low excretors by DNA mutation analysis in the glutaryl CoA dehydrogenase (GCDH) gene was performed by polymerase chain reaction and Sangers sequencing. Among 10 GA-I patients, 7 patients were found to have high excretor, and 3 were found to have low excretor phenotype. The low excretors were found to have GCDH gene mutations. The mean C5DC levels in high and low excretors were 2.61 ± 2.02μmol/L and 2.31 ± 1.00μmol/L, respectively. In high excretors, C5DC levels correlated with GA (r = 0.95). In low excretors, C5DC levels correlated with 3-OH-GA (r = 0.99). No significant difference was found between C5DC levels of high and low excretors (p = 0.82). The MS/MS, C5DC screening is a sensitive technique and detected 10 GA-I patients. Irrespective of the urine organic acid levels, Indian GA-I patients including low excretors seem to have a significantly elevated C5DC level and well above the stipulated cut-off values and therefore, expanded newborn screening is probably adequate to diagnose them.

Immunolocalization of glutaryl-CoA dehydrogenase (GCDH) in adult and embryonic rat brain and peripheral tissues

Glutaryl-CoA dehydrogenase (GCDH) is a mitochondrial enzyme that is involved in the degradation of tryptophan, lysine and hydroxylysine. Deficient enzyme activity leads to glutaric aciduria type-I (GA-I). This neurometabolic disease usually manifests with acute encephalopathic crises and striatal neuronal death in early childhood leading to an irreversible dystonic-dyskinetic movement disorder. Fronto-temporal atrophy and white matter changes are already present in the pre-symptomatic period. No detailed information on GCDH expression during embryonic development and in adulthood was available so far.Using immunofluorescence microscopy and cell-type-specific markers to localize GCDH in different tissues, we describe the differential cellular localization of GCDH in adult rat brain and peripheral organs as well as its spatiotemporal expression pattern.During embryonic development GCDH was predominantly expressed in neurons of the central and peripheral nervous system. Significant expression levels were found in epithelial cells (skin, intestinal and nasal mucosa) of rat embryos at different developmental stages. Besides the expected strong expression in liver, GCDH was found to be significantly expressed in neurons of different brain regions, renal proximal tubules, intestinal mucosa and peripheral nerves of adult rats.GCDH was found widely expressed in embryonic and adult rat tissues. In rat embryos GCDH is predominantly expressed in brain implying an important role for brain development. Interestingly, GCDH was found to be significantly expressed in different other organs (e.g. kidney, gut) in adult rats probably explaining the evolving phenotype in GA-I patients.

Higher Vulnerability of Menadione-Exposed Cortical Astrocytes of Glutaryl-CoA Dehydrogenase Deficient Mice to Oxidative Stress, Mitochondrial Dysfunction, and Cell Death: Implications for the Neurodegeneration in Glutaric Aciduria Type I.

Patients affected by glutaric aciduria type I (GA-I) show progressive cortical leukoencephalopathy whose pathogenesis is poorly known. In the present work, we exposed cortical astrocytes of wild-type (Gcdh +/+ ) and glutaryl-CoA dehydrogenase knockout (Gcdh -/- ) mice to the oxidative stress inducer menadione and measured mitochondrial bioenergetics, redox homeostasis, and cell viability. Mitochondrial function (MTT and JC1-mitochondrial membrane potential assays), redox homeostasis (DCFH oxidation, nitrate and nitrite production, GSH concentrations and activities of the antioxidant enzymes SOD and GPx), and cell death (propidium iodide incorporation) were evaluated in primary cortical astrocyte cultures of Gcdh +/+ and Gcdh -/- mice unstimulated and stimulated by menadione. We also measured the pro-inflammatory response (TNFα levels, IL1-β and NF-ƙB) in unstimulated astrocytes obtained from these mice. Gcdh -/- mice astrocytes were more vulnerable to menadione-induced oxidative stress (decreased GSH concentrations and altered activities of the antioxidant enzymes), mitochondrial dysfunction (decrease of MTT reduction and JC1 values), and cell death as compared with Gcdh +/+ astrocytes. A higher inflammatory response (TNFα, IL1-β and NF-ƙB) was also observed in Gcdh -/- mice astrocytes. These data indicate a higher susceptibility of Gcdh -/- cortical astrocytes to oxidative stress and mitochondrial dysfunction, probably leading to cell death. It is presumed that these pathomechanisms may contribute to the cortical leukodystrophy observed in GA-I patients.

Single Lysis-Salting Out Method of Genomic DNA Extraction From Dried Blood Spots.

Dried blood spots (DBS) are an important form of bio-sampling and valuable approach for storing blood samples for genetic studies. This has necessitated in developing an effective protocol to isolate genomic DNA (gDNA) from DBS samples.In this study, we have elucidated a dependable and non-hazardous "single lysis-salting out" (SLSO) protocol of gDNA extraction from DBS and compared against the available commercial kits. For the purpose of this study, blood spots were collected on S&S 903 filter cards from 10 healthy volunteers and 30 patients with glutaric aciduria type I (GA-I). The gDNA was extracted from theseDBS samples by SLSO, QIAamp® gDNA Micro kit and innuPREP forensic kit methods. The quantity and quality of gDNA obtained from these methods were determined by measuring the absorbance using a Nanodrop spectrophotometer. The SLSO method showed four-fold and eight-fold increased yield of gDNA in healthy volunteers and patient samples, respectively, compared to commercial kits (p<0.0001). The protocol was also found to be cost efficient, reducing the per sample cost to almost half. The suitability of this method for genetic studies was confirmed by performing R402W genotyping by RFLP in GA-I patients. The genotyping results showed the presence of R402W mutation in 20% (6/30) of patients. The SLSO method was found to be inexpensive, non-hazardous and a suitable technique for isolating gDNA from DBS samples for genetic studies.

A cross-sectional controlled developmental study of neuropsychological functions in patients with glutaric aciduria type I

BackgroundGlutaric aciduria type I (GA-I) is an inherited metabolic disease due to deficiency of glutaryl-CoA dehydrogenase (GCDH). Cognitive functions are generally thought to be spared, but have not yet been studied in detail.MethodsThirty patients detected by newborn screening (n = 13), high-risk screening (n = 3) or targeted metabolic testing (n = 14) were studied for simple reaction time (SRT), continuous performance (CP), visual working memory (VWM), visual-motor coordination (Tracking) and visual search (VS). Dystonia (n = 13 patients) was categorized using the Barry-Albright-Dystonia Scale (BADS). Patients were compared with 196 healthy controls. Developmental functions of cognitive performances were analysed using a negative exponential function model.ResultsBADS scores correlated with speed tests but not with tests measuring stability or higher cognitive functions without time constraints. Developmental functions of GA-I patients significantly differed from controls for SRT and VS but not for VWM and showed obvious trends for CP and Tracking. Dystonic patients were slower in SRT and CP but reached their asymptote of performance similar to asymptomatic patients and controls in all tests. Asymptomatic patients did not differ from controls, except showing significantly better results in Tracking and a trend for slower reactions in visual search. Data across all age groups of patients and controls fitted well to a model of negative exponential development.ConclusionsDystonic patients predominantly showed motor speed impairment, whereas performance improved with higher cognitive load. Patients without motor symptoms did not differ from controls. Developmental functions of cognitive performances were similar in patients and controls. Performance in tests with higher cognitive demand might be preserved in GA-I, even in patients with striatal degeneration.Electronic supplementary materialThe online version of this article (doi:10.1186/s13023-015-0379-6) contains supplementary material, which is available to authorized users.

Complementary dietary treatment using lysine-free, arginine-fortified amino acid supplements in glutaric aciduria type I — A decade of experience

The cerebral formation and entrapment of neurotoxic dicarboxylic metabolites (glutaryl-CoA, glutaric and 3-hydroxyglutaric acid) are considered to be important pathomechanisms of striatal injury in glutaric aciduria type I (GA-I). The quantitatively most important precursor of these metabolites is lysine. Recommended therapeutic interventions aim to reduce lysine oxidation (low lysine diet, emergency treatment to minimize catabolism) and to enhance physiologic detoxification of glutaryl-CoA via formation of glutarylcarnitine (carnitine supplementation). It has been recently shown in Gcdh−/− mice that cerebral lysine influx and oxidation can be modulated by arginine which competes with lysine for transport at the blood–brain barrier and the inner mitochondrial membrane [Sauer et al., Brain 134 (2011) 157–170]. Furthermore, short-term outcome of 12 children receiving arginine-fortified diet showed very promising results [Strauss et al., Mol. Genet. Metab. 104 (2011) 93–106]. Since lysine-free, arginine-fortified amino acid supplements (AAS) are commercially available and used in Germany for more than a decade, we evaluated the effect of arginine supplementation in a cohort of 34 neonatally diagnosed GA-I patients (median age, 7.43years; cumulative follow-up period, 221.6patientyears) who received metabolic treatment according to a published guideline [Kölker et al., J. Inherit. Metab. Dis. 30 (2007) 5–22]. Patients used one of two AAS product lines during the first year of life, resulting in differences in arginine consumption [group 1 (Milupa Metabolics): mean=111mg arginine/kg; group 2 (Nutricia): mean=145mg arginine/kg; p<0.001]. However, in both groups the daily arginine intake was increased (mean, 137mg/kg body weight) and the dietary lysine-to-arginine ratio was decreased (mean, 0.7) compared to infants receiving human milk and other natural foods only. All other dietary parameters were in the same range. Despite significantly different arginine intake, the plasma lysine-to-arginine ratio did not differ in both groups. Frequency of dystonia was low (group 1: 12.5%; group 2: 8%) compared with patients not being treated according to the guideline, and gross motor development was similar in both groups. In conclusion, the development of complementary dietary strategies exploiting transport competition between lysine and arginine for treatment of GA-I seems promising. More work is required to understand neuroprotective mechanisms of arginine, to develop dietary recommendations for arginine and to evaluate the usefulness of plasma monitoring for lysine and arginine levels as predictors of cerebral lysine influx.

Use of guidelines improves the neurological outcome in glutaric aciduria type I

To evaluate the effect of treatment according to current evidence-based recommendations on the neurological outcome of patients with glutaric aciduria type I (GA-I). Fifty-two patients identified by newborn screening (NBS) in Germany from 1999 to 2009 were followed prospectively. Neurological outcome was assessed by the occurrence of an acute encephalopathic crisis and the severity of a movement disorder (MD) with predominant dystonia superimposing on axial hypotonia. Outcome was evaluated in relation to therapy and therapy-independent parameters. Outcome was best in GA-I patients who were treated in full accordance with treatment recommendations (n=37; 5% MD). Deviations from recommended basic metabolic treatment (low-lysine diet, carnitine) resulted in an intermediate outcome (n=9; 44% MD), whereas disregard of emergency treatment recommendations was associated with a poor outcome (n=6; 100% MD). Treatment regimens deviating from recommendations significantly increased the risk for MD (odds ratio [OR], 35; 95% confidence interval [CI], 5.88-208.39) and acute encephalopathic crises (OR, 51.32; 95% CI, 2.65-993.49). Supervision by a metabolic center improved the outcome (18% vs 57% MD; OR, 6.17; 95% CI, 1.15-33.11), whereas migrational background and biochemical phenotype (high versus low excretor status) had no significant effect. Follow-up of neonatally diagnosed patients with GA-I in Germany clearly demonstrates that the inclusion of this rare disease in the NBS disease panel has significantly improved the neurological outcome of affected individuals. The establishment of and adherence to evidence-based treatment recommendations, and supervision by experienced metabolic centers helps to minimize the number of patients who do not benefit from NBS.

Lysine intake and neurotoxicity in glutaric aciduria type I: towards a rationale for therapy?

Glutaric aciduria type I (GA-I) is a rare cerebral organic acid disorder caused by inherited deficiency of glutaryl-CoA dehydrogenase (GCDH; EC 1.3.99.7), a mitochondrial flavoprotein catalysing the oxidative decarboxylation of glutaryl-CoA to crotonyl-CoA in the final catabolic pathways of the amino acids l-lysine, l-hydroxylysine and l-tryptophan (Goodman et al ., 1975). Biochemically, GA-I is characterized by an accumulation of the dicarboxylic acids glutaric acid (GA) and 3-hydroxyglutaric acid (3-OH-GA) as well as glutarylcarnitine (Baric et al ., 1999). Clinically, the disease course is complicated by striatal injury during an acute encephalopathic crisis, which is usually precipitated by a catabolic state (e.g. infectious diseases) in infancy or early childhood (Strauss et al ., 2003; Kolker et al ., 2006). If treated before the onset of irreversible neurological symptoms, the encephalopathic crises can be prevented in the majority of children (Strauss et al ., 2003; Naughten et al ., 2004; Kolker et al ., 2006). In particular, maintenance treatment with l-carnitine supplementation and lysine restriction is beneficial for pre-symptomatically diagnosed children (Kolker et al ., 2006). An animal model of GA-I has been developed to study pathophysiology. A detailed analysis of the histopathology, biochemistry, bioenergetics and behaviour of these mice has previously been published (Koeller et al ., 2002; Sauer et al ., 2005). In spite of high levels of GA and 3-OH-GA, these Gcdh−/− mice do not develop striatal degeneration either spontaneously or following a number of triggers, inducing a catabolic state (Koeller et al ., 2002), which contrasts with the association between catabolism and encephalopathic crises in GA-I patients. Recently, Zinnanti et al . reported in Brain (2006) that excessive dietary intake of lysine or protein produced a phenotype in Gcdh−/− mice that resembled some important clinical and neuroradiological …