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Background Glutaric acidemia is a type of multiple acyl-coenzyme A dehydrogenase deficiency, an inborn error in fatty acid metabolism. In patients with glutaric acidemia, during the perioperative period, prolonged fasting, stress, and pain have been identified as risk factors for the induction of metabolic derangement. This report describes the surgical and anesthetic management of a patient with glutaric acidemia. Case presentation A 56-year-old male patient with glutaric acidemia type 2 underwent a series of surgeries. During the initial off-pump coronary artery bypass surgery, the patient developed renal failure due to rhabdomyolysis upon receiving glucose at 2 mg/kg/min. However, in the second laparoscopic cholecystectomy, rhabdomyolysis was avoided by administering glucose at 4 mg/kg/min. Conclusions To avoid catabolism in patients with glutaric acidemia, appropriate glucose administration is important, depending on the surgical risk.

Traballo Fin de Grao en Medicina. Curso 2020-2021 Introducción: El ácido docosahexaenoico (DHA) es un ácido graso poliinsaturado de cadena larga (AGPI-CL; LC-PUFA), cuya principal fuente de entrada a nuestro organismo son los alimentos ricos en proteínas de alto valor biológico. Objetivos: Analizar los beneficios de una suplementación con ácidos grasos poliinsaturados de cadena larga (LC-PUFA) en especial el ácido docosahexaenoico, en el tratamiento de la fenilcetonuria y la aciduria glutárica I; evaluando, además, la posible deficiencia de LC-PUFA, en especial el DHA, que existe de partida en esta población a estudio, y/o su causa. Métodos: Se ha realizado una exhaustiva y ordenada revisión de las publicaciones incluidas en la base de datos PUBMED en relación con los ácidos grasos poliinsaturados de cadena larga (LC-PUFA) y la fenilcetonuria (PKU) y la aciduria glutárica 1 (GA-1). Los criterios de inclusión de los estudios analizados fueron: estudios realizados en humanos, que estuvieran publicados en inglés o español y que tuvieran abstract disponible. Únicamente se incluyeron ensayos clínicos, ensayos clínicos aleatorizados y controlados, metaanálisis, revisiones y revisiones sistemáticas. El período de búsqueda fue desde el 01/01/2000 hasta el 01/04/2020. Resultados: Se incluyeron 22 estudios en los que se analizaron los beneficios de una suplementación con ácidos grasos poliinsaturados de cadena larga (LC-PUFA) en especial el ácido docosahexaenoico, en el tratamiento de la fenilcetonuria y la aciduria glutárica I; evaluando, además, la posible deficiencia de LC-PUFA, en especial el DHA, que existe de partida en esta población a estudio, y/o su causa. No existe evidencia en cuanto a la relación de la aciduria glutárica 1 (GA-1) y los ácidos grasos poliinsaturados de cadena larga (LC-PUFA), por lo que es necesario que se investigue al respecto. Existe un déficit de LC-PUFA en la fenilcetonuria (PKU) con dos posibles explicaciones, y la suplementación con LC-PUFA es potencialmente útil y necesaria en estos pacientes, dado que solventa este déficit y parece tener, en general, efectos positivos en los potenciales evocados visuales. No hay datos concluyentes del efecto de la suplementación con DHA en el neurodesarrollo de pacientes con PKU. Conclusiones: La suplementación con LC-PUFA parece tener efectos positivos en los potenciales evocados visuales en los pacientes con PKU. Se necesitarán más investigaciones para dar con una dosis de LC-PUFA óptima y duración adecuada, de cara a su uso como suplemento en pacientes con PKU Background: Docosahexaenoic acid (DHA) is a long-chain polyunsaturated fatty acid (LC-PUFA; LC-PUFA), whose main sources of entry into our organism are foods rich in proteins of high biological value. Objectives: To analyze the benefits of supplementation with long-chain polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid, in the treatment of phenylketonuria and glutaric aciduria I; evaluating, in addition, the possible deficiency of LC-PUFA, especially DHA, that exists in this study population, and/or its cause. Methods: An exhaustive and orderly review of the publications included in the PUBMED database regarding long-chain polyunsaturated fatty acids (LC-PUFA) and phenylketonuria (PKU) and glutaric aciduria 1 (GA-1) was performed. The inclusion criteria for the studies analyzed were: studies conducted in humans, published in English or Spanish and with available abstracts. Only clinical trials, randomized and controlled clinical trials, meta-analyses, reviews and systematic reviews were included. The search period was from 01/01/2000 to 01/04/2020. Results: 22 studies were included in which the benefits of supplementation with long-chain polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid, in the treatment of phenylketonuria and glutaric aciduria I were analyzed; evaluating, in addition, the possible deficiency of LC-PUFA, especially DHA, that exists in this study population, and/or its cause. There is no evidence regarding the relationship between glutaric aciduria 1 (GA-1) and long-chain polyunsaturated fatty acids (LC-PUFA), so more research is needed. There is a deficit of LC-PUFA in phenylketonuria (PKU) with two possible explanations, and LC-PUFA supplementation is potentially useful and necessary in these patients, since it solves this deficit and seems to have, in general, positive effects on visual evoked potentials. There are no conclusive data on the effect of DHA supplementation on neurodevelopment in PKU patients. Conclusions: LC-PUFA supplementation appears to have positive effects on visual evoked potentials in PKU patients. Further research will be needed to find an optimal LC-PUFA dose and appropriate duration for supplementation in PKU patients Introdución: O ácido docosahexaenoico (DHA) é un acido graxo poliinsaturado de cadena longa (AGPI-CL; LC-PUFA), no que a fonte principal para incorporarse o noso organismo son os alimentos ricos en proteínas de alto valor biolóxico. Obxectivos: Analizar os beneficios dunha suplementación con ácidos graxos poliinsaturados de cadea longa (LC-PUFA), especialmente ácido docosahexaenoico, no tratamento da fenilcetonuria e da aciduria glutárica I; avaliando, ademais, a posible deficiencia de LC-PUFA, especialmente DHA, que inicialmente existe nesta poboación a estudo e / ou a súa causa. Métodos: Realizouse unha revisión exhaustiva e ordenada das publicacións incluídas na base de datos PUBMED en relación aos ácidos graxos poliinsaturados de cadea longa (LC-PUFA) e á fenilcetonuria (PKU) e á aciduria glutárica 1 (GA-1). Os criterios de inclusión dos estudos analizados foron: estudos realizados en humanos, que foron publicados en inglés ou español e que tiñan un resumo dispoñible. Só se incluíron ensaios clínicos, ensaios clínicos aleatorios e controlados, metaanálises, revisións e revisións sistemáticas. O período de busca foi do 01/01/2000 ao 04/01/2020. Resultados: Incluíronse vinte e dous estudos nos que se incluían os beneficios da suplementación con ácidos graxos poliinsaturados de cadea longa (LC-PUFA), especialmente o ácido docosahexaenoico, no tratamento da fenilcetonuria e da aciduria glutárica. avaliando, ademais, a posible deficiencia de LC-PUFA, especialmente DHA, que inicialmente existe nesta poboación de estudo e / ou a súa causa. Non hai evidencias sobre a relación entre a aciduria glutárica 1 (GA-1) e os ácidos graxos poliinsaturados de cadea longa (LC-PUFA), polo que é necesario investigar. Hai un déficit de LC-PUFA en fenilcetonuria (PKU) con dúas explicacións posibles, e a suplementación de LC-PUFA é potencialmente útil e necesaria nestes pacientes, xa que resolve este déficit e parece ter, en xeral, efectos positivos sobre os potenciais visuais evocados. Non hai datos concluíntes sobre o efecto da suplementación con DHA no neurodesenvolvemento en pacientes con PKU. Conclusións: A suplementación con LC-PUFA parece ter efectos positivos sobre os potenciais evocados visuais en pacientes con PKU. Necesitaranse máis investigacións para atopar unha dose óptima de LC-PUFA e unha duración adecuada para a suplementación en pacientes con PKU

Purpose Glutaric acidemia type 1 (GA1), a rare hereditary metabolic disease caused by biallelic mutations of GCDH, can result in acute or insidious striatal degeneration within the first few years of life. We reviewed the orthopaedic sequelae and management of 114 neurologically injured patients with a confirmed molecular diagnosis of GA1. Methods We performed a retrospective chart review spanning 28 years identifying 114 GA1 patients, most from the Old Order Amish population of Lancaster County, Pennsylvania, who were homozygous for a pathogenic founder variant of GCDH (c.1262C>T). We collected demographics, medical comorbidities, muscle tone patterns, Gross Motor Function Classification System level, gastrostomy tube status, seizure history, inpatient events, orthopaedic diagnoses and operative characteristics. Results Over an average follow-up of 4.7 ± 3.4 years, 24 (21%) of 114 patients had musculoskeletal problems requiring orthopaedic consultation. Scoliosis (n = 14), hip dislocation (n = 8/15 hips), hip subluxation (n = 2/three hips), and windswept hip deformity (n = 2) in the spine and hip joint were most common. In total, 35 orthopaedic surgeries were performed in 17 (71%) patients. The most common primary operations were one-stage procedures with proximal femoral varus derotation osteotomy and/or pelvic osteotomy (n = 8/14 hips) for subluxation or dislocation. In all, 11 patients had posterior spinal fusion for severe scoliosis. With the recommended metabolic management, there were no disease-specific complications in this cohort. Conclusions Children with GA1 who have static striatal lesions are at risk for musculoskeletal complications, especially scoliosis and hip dislocation, and appropriate operative management requires consultation with a metabolic specialist with specific considerations for fluid management and nutrition. Level of Evidence IV

Glutaric acidemia type 1 (GA1) is a disorder of cerebral organic acid metabolism resulting from biallelic mutations of GCDH. Without treatment, GA1 causes striatal degeneration in80% of affected children before two years of age. We analyzed clinical, biochemical, and developmental outcomes for 168 genotypically diverse GA1 patients managed at a single center over 31 years, here separated into three treatment cohorts: children in Cohort I (n = 60; DOB 2006-2019) were identified by newborn screening (NBS) and treated prospectively using a standardized protocol that included a lysine-free, arginine-enriched metabolic formula, enteral l-carnitine (100 mg/kg•day), and emergency intravenous (IV) infusions of dextrose, saline, and l-carnitine during illnesses; children in Cohort II (n = 57; DOB 1989-2018) were identified by NBS and treated with natural protein restriction (1.0-1.3 g/kg•day) and emergency IV infusions; children in Cohort III (n = 51; DOB 1973-2016) did not receive NBS or special diet. The incidence of striatal degeneration in Cohorts I, II, and III was 7%, 47%, and 90%, respectively (p .0001). No neurologic injuries occurred after 19 months of age. Among uninjured children followed prospectively from birth (Cohort I), measures of growth, nutritional sufficiency, motor development, and cognitive function were normal. Adherence to metabolic formula and l-carnitine supplementation in Cohort I declined to 12% and 32%, respectively, by age 7 years. Cessation of strict dietary therapy altered plasma amino acid and carnitine concentrations but resulted in no serious adverse outcomes. In conclusion, neonatal diagnosis of GA1 coupled to management with lysine-free, arginine-enriched metabolic formula and emergency IV infusions during the first two years of life is safe and effective, preventing more than 90% of striatal injuries while supporting normal growth and psychomotor development. The need for dietary interventions and emergency IV therapies beyond early childhood is uncertain.

Summary Disruption of mitochondrial respiration in the nematode Caenorhabditis elegans can extend lifespan. We previously showed that long‐lived respiratory mutants generate elevated amounts of α‐ketoacids. These compounds are structurally related to α‐ketoglutarate, suggesting they may be biologically relevant. Here, we show that provision of several such metabolites to wild‐type worms is sufficient to extend their life. At least one mode of action is through stabilization of hypoxia‐inducible factor‐1 (HIF‐1). We also find that an α‐ketoglutarate mimetic, 2,4‐pyridinedicarboxylic acid (2,4‐PDA), is alone sufficient to increase the lifespan of wild‐type worms and this effect is blocked by removal of HIF‐1. HIF‐1 is constitutively active in isp‐1(qm150) Mit mutants, and accordingly, 2,4‐PDA does not further increase their lifespan. Incubation of mouse 3T3‐L1 fibroblasts with life‐prolonging α‐ketoacids also results in HIF‐1α stabilization. We propose that metabolites that build up following mitochondrial respiratory dysfunction form a novel mode of cell signaling that acts to regulate lifespan.

Glutaric acidemia type 1 (GA1) is a rare inherited metabolic disorder which goes underdiagnosed due to its latency period and subtle presentation. A pilot clinical study was conducted to assess the usefulness, specificity and sensitivity of the tandem mass (MS/MS) spectrometer, specifically the Abbott (AB) Sciex 3200, in the screening for GA1 using dried blood spots. A total of 17,100 specimens, comprising pediatric patients and healthy newborns, were screened from June 2012 to June 2014. A selection criterion was applied to increase the range of samples tested. 14 of the total specimens tested presumptive positive for GA1, of whom all were symptomatic. The diagnosis was confirmed in 4 of the 14 cases and they were started on treatment. 4 cases expired before confirmation. The remaining cases were empirically started on treatment. Most of the patients responded favorably to the dietary management. One important observation was that the older symptomatic children diagnosed with GA1 had poorer outcomes in terms of recovery of delayed milestones and mental deterioration, further emphasizing the need for early diagnosis of organic acidemias along with the other biochemical defects. Tandem mass spectrometry was found to be more than 93.33% sensitive and more than 99.42% specific. The screening test proved to be very simple and economical.

Multiple acyl-CoA dehydrogenase deficiency (MADD), also known as glutaric acidemia or glutaric aciduria type II, can be caused by mutations in three different genes (ETFA, ETFB, ETFDH), which are all involved in electron transfer in the mitochondrial respiratory chain. In most patients MADD is caused by mutations in the ETFDH gene (Table 63.1), encoding the electron transfer flavoprotein dehydrogenase. MADD results in large excretion of glutaric, lactic, ethylmalonic, butyric, isobutyric, 2-methyl-butyric, and isovaleric acids.

The analysis of characteristic urinary acidic markers such as glutaric, 3-hydroxyglutaric, 2-hydroxyglutaric, adipic, suberic, sebacic, ethylmalonic, 3-hydroxyisovaleric and isobutyric acid constitutes the recommended follow-up testing procedure for glutaric acidemia type 1 (GA-1) and type 2 (GA-2). The goal of the work herein presented is the development of a fast and simple method for the quantification of these biomarkers in human urine. The proposed analytical approach is based on the use of solid phase microextraction (SPME) combined with gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) afterward a rapid derivatization of acidic moieties by propyl chloroformate, propanol and pyridine. Trueness and precision of the proposed protocol, tested at 5, 30 and 80mgl-1, provided satisfactory values: recoveries were in the range between 72% and 116% and the relative standard deviations (RSD%) were between 0.9% and 18% (except for isobutyric acid at 5mgl-1). The LOD values achieved by the proposed method ranged between 1.0 and 473μgl-1.

High anion gap metabolic acidosis (HAGMA) is a frequently observed laboratory finding in critically ill patients. Usually HAGMA occurs as a result of common disease processes. However, rare diseases often manifest themselves by mimicking common disease processes with subtle differences, occasionally making the diagnosis challenging. In the following case, the metabolic workup of a patient revealed HAGMA acidosis. After ruling out the usual causes, diligent investigation by our team of subtle laboratory clues revealed a rare cause for HAGMA.

The first crystal structure is reported of a glutaryl-CoA dehydrogenase in the apo state without flavin adenine dinucleotide cofactor bound. Additional structures with small molecules complexed in the catalytic active site were obtained by fragment-based screening., Glutaric acidemia type 1 is an inherited metabolic disorder which can cause macrocephaly, muscular rigidity, spastic paralysis and other progressive movement disorders in humans. The defects in glutaryl-CoA dehydrogenase (GCDH) associated with this disease are thought to increase holoenzyme instability and reduce cofactor binding. Here, the first structural analysis of a GCDH enzyme in the absence of the cofactor flavin adenine dinucleotide (FAD) is reported. The apo structure of GCDH from Burkholderia pseudomallei reveals a loss of secondary structure and increased disorder in the FAD-binding pocket relative to the ternary complex of the highly homologous human GCDH. After conducting a fragment-based screen, four small molecules were identified which bind to GCDH from B. pseudomallei. Complex structures were determined for these fragments, which cause backbone and side-chain perturbations to key active-site residues. Structural insights from this investigation highlight differences from apo GCDH and the utility of small-molecular fragments as chemical probes for capturing alternative conformational states of preformed protein crystals.

The association of genetic factors and cerebral infarction (CI) has long been established. A positive family history alone is a recognized risk factor for CI and vascular events in general. However, there are certain inherited conditions that further increase the risk of stroke. These conditions are generally metabolic and mitochondrial genetic defects that have variable modes of inheritance. This article reviews major inherited metabolic disorders that predispose an individual to CI. Ten main conditions will be discussed: Fabry's disease, cerebrotendinous xanthomatosis, tangier disease, familial hypercholesterolemia, homocystinuria, methylmalonic acidemia, glutaric aciduria type I, propionic acidemia, ornithine transcarbamylase deficiency and mitochondrial encephalopathy, lactic acidosis and stroke-like phenomenon.

Synaptosomes and plasma membrane preparations from brain of 30-day-old rats were incubated with glutaric acid at final concentrations ranging from 10 nM to 1 mM for the determination of glutamate uptake and binding, respectively. [3H]Glutamate uptake into synaptosomes was inhibited by approximately 50% by 1 mM glutaric acid, corresponding to the concentration found in brain of glutaric acidemic children. In addition, in the presence of extracellular Na+ concentrations, the same dose of glutaric acid decreased by about 30% [3H]glutamate binding to brain plasma membranes. The results indicate that the inhibition of both glutamate uptake into synaptosomes and glutamate binding to plasma synaptic membranes by the metabolite could result in elevated concentrations of the excitatory neurotransmitter in the synaptic cleft, potentially causing excitotoxicity to neural cells, a fact that may be related to the brain damage characteristic of glutaric acidemia type I.

We report a case of acquired protein energy malnutrition with associated zinc deficiency in an 18-month-old boy with type 1 glutaric acidemia. Physical examination findings included generalized nonpitting edema, widespread desquamative plaques, and sparse hair with a reddish tinge. Laboratory abnormalities included low levels of zinc, albumin, alkaline phosphatase, and iron. A review of skin manifestations of nutritional deficiencies, specifically kwashiorkor, is presented, as well as the relatively new entity called acrodermatitis dysmetabolica.

The neuropathological findings in a 6 1 2 - year-old boy with glutaric acidemia (GA) are described, and the pathology of 7 additional literature cases is briefly reviewed. Bilateral striatal degeneration and spongy change of the white matter were the salient features in this case and seem to represent the cardinal pathological features of the disease. Spongy myelinopathy was the result of intramyelinic vacuolation due to splitting of the myelin sheath along the intraperiod line, as illustrated here for the first time in GA. Based on morphological, biochemical and pharmacological data from humans and experimental animals, it is hypothesized that excitotoxin-mediated neuronal damage may account for the striatal degeneration, while toxic effect on myelin metabolism by the metabolic derangement of GA may explain the widespread white matter changes.

Glutaric acidemia type I (GA-I) is a rare, autosomal recessive metabolic disorder that leads to severe dystonia, basal ganglia degeneration, and bilaterally enlarged anterior middle cranial fossae. The current management of this disease includes early diagnosis with newborn screening, prevention of catabolism, carnitine supplementation, and a strict dietary protein restriction. Neurosurgical evaluation and intervention may be necessary in patients with structural lesions associated with this disease. In this report, the authors present two pediatric patients with GA-I and discuss the neurosurgical aspects of this rare medical disorder.

We report two women with glutaric acidemia type I in whom the diagnosis was unsuspected until a low carnitine level was found in their newborn children. Both mothers had low carnitine in plasma. In the first, organic acid analysis was only done after fibroblast studies revealed normal carnitine uptake. Having learned from the first family, organic acid analysis was done immediately in the mother of family 2. In both, the plasma acylcarnitine profile was normal but both excreted the metabolites typical of their disorder. One of the women was a compound heterozygote for distinct mutations in the glutaric acid dehydrogenase gene, whereas the second was either homozygous or hemizygous for a mutation in Exon 6 of the gene.

Glutaric acidemia type I (GA-I) is an inherited metabolic disease characterized by striatal degeneration, seizures, and accumulation of glutaric acid (GA). Considering that GA impairs energy metabolism and induces reactive species generation, we investigated whether the acute administration of creatine, an amino acid with antioxidant and ergogenic properties, protects against the seizures and neurochemical alterations (inhibition of Na + ,K + -ATPase and increased protein carbonylation) induced by the intrastriatal injection of GA (4 μmol/striatum). We also investigated whether creatine protected against the GA-induced inhibition of glutamate uptake in vitro . Creatine administration (300 mg/kg, p.o.) decreased seizures (evidenced by electrographic changes), protein carbonylation and Na + ,K + -ATPase inhibition induced by GA. However, creatine, at a dose capable of fully preventing GA-induced protein carbonylation (50 and 150 mg/kg, p.o.), did not prevent convulsions and Na + ,K + -ATPase inhibition, suggesting that the anticonvulsant activity of creatine in this experimental model is not related to its antioxidant action. Creatine also protected against the GA-induced inhibition of l -[ 3 H]glutamate uptake in synaptosomes, suggesting that creatine may reduce the deleterious effects of GA by maintaining glutamate uptake in the synaptic cleft. Therefore, considering that creatine significantly attenuates the deleterious effects of GA assessed by behavioral and neurochemical measures, it is plausible to propose the use of this amino acid as an adjuvant therapy in the management of glutaric acidemia.

Background Disorders of organic acid (OA) metabolism are generally detected by qualitative analysis of urine organic acids by gas chromatography/mass spectrometry (GC/MS) which was well established in developed countries since 1980s. Confirmation of the diagnosis of organic acid disorders by OA analysis, enzyme analysis and molecular study is a difficult task in developing countries. Methods During 2001–2004, we had analysed 442 urine samples in 365 patients and identified 12 cases of organic acid disorders. Results We identified the following disorders: alkaptonuria (ALK) = 1, isovaleric acidemia (IVA) = 3, propionic acidemia (PA) = 2, methylmalonic acidemia (MMA) = 3, glutaric aciduria, type I (GA-I) = 1, multiple carboxylase deficiency (MCD) = 1, and glutaric acidemia, type II (GA-II) = 1. Conclusions OA disorders had never been diagnosed in Thailand before, until GC/MS technology was introduced to Thailand in 2001. Urine OA analysis also provided a diagnostic clue to other inborn errors of metabolism including amino acid disorders, urea cycle disorders, disorders of carbohydrate metabolism, and mitochondrial fatty acid oxidation disorders. Since then, we were able to diagnose numerous disorders, which led to prompt treatment and better outcome in our patients.

Glutaric acidemias comprise different disorders resulting in an increased urinary excretion of glutaric acid. Glutaric acidemia type 1 (GA-1) is an autosomal recessive disorder of lysine, hydroxylysine, and tryptophan metabolism caused by deficiency of glutaryl-CoA dehydrogenase. It results in the accumulation of 3-hydroxyglutaric and glutaric acid. Affected patients can present with brain atrophy and macrocephaly and with acute dystonia secondary to striatal degeneration in most cases triggered by an intercurrent childhood infection with fever between 6 and 18 months of age. This disorder can be identified by increased glutaryl (C5DC) carnitine on newborn screening. Urine organic acid analysis indicates the presence of excess 3-OH-glutaric acid, and urine acylcarnitine profile shows glutaryl carnitine as the major peak. Therapy consists in carnitine supplementation to remove glutaric acid, a diet restricted in amino acids capable of producing glutaric acid, and prompt treatment of intercurrent illnesses. Early diagnosis and therapy reduce the risk of acute dystonia in patients with GA-1.

We report a child initially diagnosed with promethazine-induced dystonia despite a lack of response to diphenhydramine therapy. On further evaluation, the child was diagnosed with glutaric acidemia, type I (GA-I), an autosomal recessive inborn error of metabolism caused by the deficiency of glutaryl-CoA dehydrogenase. The characteristic clinical feature of GA-I is an acute encephalopathic and neurologic crisis typically occurring during a catabolic state. Despite slow improvement, many patients do not fully recover from a neurologic crisis, and residual neurologic morbidity can be significant. Although newborn screening using tandem mass spectrometry is expected to enable presymptomatic diagnosis of GA-I, this patient was not detected by newborn screening with tandem mass spectrometry. Therefore, a high suspicion of GA-I must be maintained in the evaluation of childhood dystonia, even when newborn screening results are reportedly normal.

For the past 30 years, neonatal screening programs have been performed largely by using the bacterial inhibition assays developed by Dr Robert Guthrie. These programs focused on a small number of diseases such as phenylketonuria and maple syrup urine disease and involved one test for each disease. During the same period many new diseases were discovered, such as organic acidemias and fatty acid oxidation defects, and they presented a diagnostic challenge to biochemical laboratories. Different mass spectrometric approaches have been the main tools for the diagnosis; however, each has its own limitation. Recently, electrospray tandem mass spectrometry (MS/MS) has provided an alternative automated high throughput, specific, and broad-spectrum approach to screening for a relatively large number of disorders, including those covered by bacterial inhibition assays tests. By using specific scan functions, a large number of amino acids and acylcarnitines in blood spots are quantified in 2 minutes analytical time. A new scan function is described here for quantification and screening for argininosuccinic acid in blood spots, which is a key metabolite in the diagnosis of argininosuccinase deficiency. We describe the results of a 3-year tandem MS/MS-based neonatal study that was performed in our newborn population. We screened 27,624 blood spots and identified 20 cases yielding a frequency of 1:1,381. No false-negative cases were identified, but several false-positive cases were eliminated by repeat analysis by MS/MS of blood or by other means. We also used MS/MS analysis of urine or blood either for confirmation of initial positive results or for follow-up of treatment, such as in glutaric acidemia, citrullinemia, argininosuccinase deficiency, and biopterin-dependent phenylketonuria.

Two siblings who were found to have deficiency of glutaryl-CoA dehydrogenase were identified by the presence of large amounts of 3-hydroxyglutaric acid in the urine. Patients with this disease, termed glutaric acidemia or glutaric acidemia Type I, usually present with large amounts of glutaric acid in the urine, and amounts of 3-hydroxyglutaric acid found are less. Patients were ataxic and dystonic. Intelligence was normal. 3-Hydroxyglutaric acid in the urine was quantified by organic acid analysis via gas chromatography mass spectrometry (GCMS) and by stable isotope-dilution (internal standard) GCMS. Glutaryl-CoA dehydrogenase activity in cultured fibroblasts was found to be 2% of the control level. The nature of the mutations was identified, and both patients were found to be compound heterozygotes for R227P, which changed an arginine to a proline, and E365K, which changed a glutamate to a lysine.

The effect of intrastriatal administration of glutaric acid (GTR), a metabolite that accumulates in glutaric acidemia type I (GA-I), on the behavior of adult male rats was investigated. After cannula placing, rats received unilateral intrastriatal injections of GTR buffered to pH 7.4 with NaOH or NaCl. GTR induced rotational behavior toward the contralateral side of injection and clonic convulsions in a dose-dependent manner. Rotational behavior was prevented by intrastriatal preadministration of DNQX and muscimol, but not by the preadministration of MK-801. Convulsions were prevented by intrastriatal preinjection of muscimol. This study provides evidence for a participation of glutamatergic non-NMDA and GABAergic mechanisms in the GTR-induced behavioral alterations. These findings may be of value in understanding the physiopathology of the neurological dysfunction in glutaric acidemia.

Detection and diagnostic confirmation of the mild variants of glutaric acidemia, type II (GAII), also termed ethylmalonic-adipic aciduria, and short chain acyl-CoA dehydrogenase deficiency (SCAD) and its variants are problematic and challenging at both the clinical, biochemical and molecular levels. The mild variants of GAII result from partial deficiencies of either electron transfer flavoprotein or its dehydrogenase and have highly variable clinical presentations and often ephemeral metabolite excretion. Direct assay of these latter two enzymes is difficult and performed at only a few laboratories worldwide. The clinical, biochemical, enzymatic, and molecular variation in SCAD is great and complicated by the presence of two common allelic variants, 625G/A and 511C/T, whose effects on enzymatic activities are not fully understood. Quantitation of urine organic acids, plasma acyl-camitines and urinary acyl-glycines may not suffice to clearly identify patients with these disorders due to variations in clinical status, substrate flux into the partially impaired pathways, and genetic heterogeneity. Therefore, we have modified an existing radioHPLC method for analysis of acyl-3H-carnitine esters in skin fibroblasts to optimize detection of these disorders (Schmidt-Sommerfeld, et al. Pediatr.Res, 44:210, 1998). Incubating fibroblasts with the branched-chain amino acids, leucine, isoleucine and valine, as well as palmitale, improves detection of the mild GAII variants; the propionyl-carnitine to isovaleryl/α-methyl butyryl-carnitine ratio is a very sensitive index of impaired dehydrogenation of the branched chain acyl-CoAs. For SCAD and its variants, butyryl-carnitine content is a very sensitive measure of SCAD-mediated butyryl-CoA dehydrogenation in intact cells. In normal cells, butyryl-carnitine content is less than 2% of total cellular acyl-camitine content, while it ranges from 10 to 25% in well defined SCAD cases lacking enzyme activity, antigen and harboring two pathogenetic mutations. In addition, we are routinely identifying patients who have clearly impaired SCAD activity, as judged by fibroblast butyryl-carnitine accumulations of 4 to 8%, who probably represent genetic compounds for the 625A/G and 511C/T variant alleles and/or other pathogenetic mutations. RadioHPLC analysis of fibroblast acyl-carnitines permits uniform, optimal challenging of the metabolic pathways in question, while minimizing the metabolite variation seen in plasma and urine analyses from patients with varying clinical, metabolic and molecular conditions. It is an important adjunct to the laboratory diagnosis of the fatty acid oxidation disorders.

A19-year-old woman with mild myopathie symptoms from age 6 and fasting intolerance presented with a Reye-like syndrome and a myopathy. Investigations disclosed a lipid storage myopathy, type II glutaric acidemia, and carnitine deficiency in skeletal muscle. Riboflavin and carnitine treatment corrected the metabolic abnormalities and she improved clinically. She later died from pulmonary complications secondary to aspiration. Subsequent studies established electron transfer flavoprotein:ubiquinone oxidoreductase (ETF:QO) deficiency (fibroblast ETF:QO activity was 2.9 mU/mg, normal range is 14.1 ± 3.8 mU/mg) as the cause of her illness. This is the first documented case of ETF:QO diagnosed in an adult.

Glutaric acidemia, which is due to inherited deficiency of glutaryl-CoA dehydrogenase, is characterized clinically by progressive dystonia and dyskinesia in childhood, and pathologically by degeneration of the caudate and putamen. Results using newer imaging techniques (computer tomography and magnetic resonance image scanning) suggest that neurological involvement in this condition begins before birth, and that gliosis of the basal ganglia is a relatively late event. Glutaric acidemia type II is usually due to inherited deficiency of electron transfer flavoprotein (ETF) or ETF:ubiquinone oxidoreductase, but some patients with typical disease may have another, to date undefined, abnormality. There may also be a clinical phenotype of glutaric acidemia type II which, like glutaryl-CoA dehydrogenase deficiency, is characterized by a movement disorder and by degeneration of the basal ganglia.

Studies are reported on two siblings with a neurodegenerative disorder, glutaric aciduria and glutaric acidemia. The glutaric aciduria was increased by oral administration of l -lysine, which is metabolized through glutaryl-CoA, and decreased by lowering protein intake. The metabolism of [1,5-14C] glutaryl-CoA was deficient in the peripheral leukocytes of the patients. The results are compatible with an inherited deficiency of glutaryl-CoA dehydrogenase. It is speculated, but not proved, that the biochemical abnormality is causally related to the central nervous system dysfunction.

Glutaric acidemia, type I, is an organic acidemia associated with a progressive neurologic disorder. 1 By 1 year of age, affected individuals generally have recurrent episodes of vomiting and lethargy associated with metabolic acidosis. Progressive neurologic defici ts include dysarthria, dystonia, and choreoathetosis. Most affected Children are also mentally retarded. The presumptive diagnosis of GA-I is made by gas chromatography-mass spectrometry of urine revealing peaks of glutaric acid and its principal metabolites 3-OH-glutarate and glutaconate. The enzyme deficiency, glutaryl CoA dehydrogenase, is demonstrable in leukocytes, fibroblasts, and hepatocytes. 2 Therapeutic approaches have included low-protein diets and diets low in tryptophan and lysine, the precursors of glutaryl CoA. 3 Riboflavin (as flavin adenine dinucleotide), a cofactor of glutaryl CoA dehydrogenase, has been given to enhance residual enzyme activity? L-Carnitine has been used to stimulate the formation and excretion of shortchain acylcarnitine derivatives of glutaric acid. 4 Finally, because of evidence of inhibition of synthesis of G A B A by glutaric acid and the presence of decreased G A B A in brains of affected individuals, the G A B A analog baclofen has been given) With these techniques, progression of symptoms has been arrested in a number of cases but little clinical improvement has resulted? -8 The present report concerns a boy with GA-I who had progressive "dystonic cerebral palsy" associated with basal ganglia degeneration and who responded to riboflavin and L-carnitine therapy with evidence of biochemical and clinical improvement.