Aciduria Research Articles

Expert consensus on screening, diagnosis and treatment of multiple carboxylase deficiency.

Multiple carboxylase deficiency (MCD) includes autosomal recessive holocarboxylase synthetase (HLCS) deficiency and biotinidase (BTD) deficiency, which are caused by and gene mutations respectively. Neonatal screening for HLCS deficiency is based on 3-hydroxyisovaleryl carnitine in dry blood filter paper, and BTD deficiency is based on BTD activity determination. HLCS deficiency and BTD deficiency are characterized by neurocutaneous syndrome and organic aciduria, however, they are different in onset age, neurological symptoms and metabolic decompensation, which needed to be differentiated from acquired biotin deficiency or other genetic metabolic diseases. The diagnosis of the disease requires a combination of biochemical characteristics of hematuria, enzyme activity determination and genetic test. Routine biotin doses are effective for most MCD patients. This consensus is intended to benefit early screening and diagnosis of MCD.

EP007: Delayed onset hyperammonemic encephalopathy in an adult with GLUD1 deficiency

Hyperammonemic encephalopathy is characterized by altered mental status due to toxic accumulation of ammonia in the circulation. Prolonged hyperammonemia can result in persistent seizures, cerebral edema, coma, and death. Therefore, prompt evaluation for underlying cause and initiating appropriate therapy is crucial in the management of this condition. In adults, common causes of hyperammonemia include hepatic dysfunction, infections, portosystemic shunting, and medications like valproic acid. Rarely, urea cycle defects and organic acidemias may present in the adulthood.

Organic Acidemias.

Organic Acidemias.

Glutaric Aciduria Type 1

Glutaric Aciduria Type 1

The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation

Mitochondria control cellular fate by various mechanisms and are key drivers of cellular metabolism. Although the main function of mitochondria is energy production, they are also involved in cellular detoxification, cellular stabilization, as well as control of ketogenesis and glucogenesis. Conditions like neurodegenerative disease, insulin resistance, endocrine imbalances, liver and kidney disease are intimately linked to metabolic disorders or inflexibility and to mitochondrial dysfunction. Mitochondrial dysfunction due to a relative lack of micronutrients and substrates is implicated in the development of many chronic diseases. l-carnitine is one of the key nutrients for proper mitochondrial function and is notable for its role in fatty acid oxidation. l-carnitine also plays a major part in protecting cellular membranes, preventing fatty acid accumulation, modulating ketogenesis and glucogenesis and in the elimination of toxic metabolites. l-carnitine deficiency has been observed in many diseases including organic acidurias, inborn errors of metabolism, endocrine imbalances, liver and kidney disease. The protective effects of micronutrients targeting mitochondria hold considerable promise for the management of age and metabolic related diseases. Preventing nutrient deficiencies like l-carnitine can be beneficial in maintaining metabolic flexibility via the optimization of mitochondrial function. This paper reviews the critical role of l-carnitine in mitochondrial function, metabolic flexibility and in other pathophysiological cellular mechanisms.

Fumarase deficiency: a difficult diagnosis and a challenging treatment approach

Introduction: Fumarase deficiency is a rare autosomal metabolic disease that curse with hypotonia, hyperlacticaemia and seizures. Diagnosis based in laboratory test might be done carefully, as most of metabolic diseases present similar symptomatology: hypotony, convulsions, lactic and pyruvic acidemia.
 Method: The objective is to analyse the pharmacological and nutritional approach of a neonate who presented symptoms of metabolic congenital disorders.
 Results: The patient is a three-month girl with heterozygote mutation in fumarase gene, who presented clinical manifestations of the altered enzyme function. She presented hyperlacticaemia, organic aciduria and alterations of amino acid levels. First diagnosis suspected was pyruvate dehydrogenase deficiency, so nutritional treatment with ketogenic diet was initiated. After medical discharge, she was hospitalized in emergency basis with cardiac arrest and metabolic decompensation. Genetic test revealed a heterozygote mutation in fumarase. Clinical symptomatology could have worsened because of the difficult diagnosis.
 Conclusions: Nutritional and pharmacological treatment of fumarase deficiency is considered essential for the patient’s evolution, but further researchers must be carried out to profoundly understand the mechanism underlying metabolic inborn errors. Multidisciplinary teams would manage the disease from the point of view of diverse clinician experts so the correct diagnosis and treatment would be decided with precision.

Inborn Errors of Metabolism Referrals- Shahid Sadoughi Hospital: A Cross- Sectional Study

Background: Inborn Errors of Metabolism (IEMs) are a group of heterogeneous disorders resulting from absent or decreased metabolic pathway activity. They are typically rare, but are more common in consanguineous population. Methods: In this cross sectional study, all children with symptoms suspicious for IEMs who referred to Shahid Sadoughi Hospital in Yazd during a 5-year period (2013-2018) were investigated for metabolic diseases. The diagnoses were further confirmed by clinical symptoms and biochemical analysis. IEMs type, age of diagnosis, family history and disease outcome were recorded. Results: In this study, 39 symptomatic children with a median age of 48 months were diagnosed with different types of metabolic diseases. About 64.1% of the patients were born from consanguineous marriage. The patients’ mean age at the time of diagnosis was 25.3 ± 5.1 months. The most frequent disorders were organic acidemias which were found in 12 patients (30.8%), lysosomal storage disorders which were found in 8 patients (20.5%), and amino acid disorders excluding phenylketonuria which was found in 8 patients (20.5%). Most of the patients (60%) were diagnosed before the age of 6 months. Mortality from metabolic disorders was 5 (12.8%). The rest of the patients (22 cases, 56.4 %) had developmental delay. Conclusion: It was found that the prevalence of inherited metabolic disorders was higher in countries with a high prevalence of consanguineous marriage, such as Iran. More extensive newborn screening is needed for ensuring early diagnosis of these patients given that delay in diagnosis of this disorder may be associated with high morbidity and mortality.

Brain MRI findings of a glutaric aciduria type I: A case report and review of the literature

Brain MRI findings of a glutaric aciduria type I: A case report and review of the literature

Clinico-Biochemical Presentation of Classical Organic Aciduria Presenting as Intoxication in Tertiary Care Hospital of Peshawar

Background: About 5 million children died in 2017 in developing countries alone, amongst them 15-20% are due to inherited metabolic disorders. Inherited metabolic disorders like Methyl Malonic Aciduria, Isovaleric aciduria, Glutaric Aciduria type 1, Urea cycle defects, Maple syrup urine disease & multiple carboxylase deficiency present mostly as intoxication, ataxia and convulsions Objective:To find the pattern of classical organic aciduria in children of different age and gender Methodology: This cross-sectional descriptive study was conducted at Paediatrics department of Town Women & Children Hospital, Peshawar from Aug 2018- Aug 2020. Patients aged 0-24 months were included in the study based on inclusion criteria.Clinical data, preliminary investigations and urinary organic acids profile were collected. Data were analysed using SPSS version 21. Results: Out of 178 total patients, 36 patients were diagnosed with classical Organic aciduria in this present study. Mean age of the study population was 0.865+/- 1.07654 years and range of 1 - 2 years. About 20(53%) cases were males, while 16(47%) cases were females. Major clinical and biochemical findings included seizures, feeding difficulties, developmental delay, neurological impairment, and motor weakness, hypoglycemic and metabolic acidosis. Conclusion: The cases positive for inherited metabolic disorder showed a significant prevalence. Methyl Malonic Aciduria was the commonest of the OAs found in Northern areas of Pakistan followed by 3- Methyl Glutaconic aciduria.Simple heel prick test alongside blood gas analysis and confirmatory test by urinary Gas Chromatography Mass Spectrometry were helpful in diagnosis of such inherited metabolic disorder. Keywords: Intoxication; Organic aciduria;Ethyl Malonic aciduria; Fumaric Aciduria

Вплив альтерації гомеостазу глюкози на водно-електролітний баланс та кислотно-основний стан у пацієнтів із цукровим діабетом

Незважаючи на успіхи в терапії цукрового діабету, частота виникнення ускладнень, зокрема порушення водно-електролітного та кислотно-основного стану, останніми роками не зменшилась. Цікаво відмітити той факт, що клінічні прояви такого грізного ускладнення, як діабетичний кетоацидоз, уперше описав Дрешфельд у 1886 році. Відтоді і до початку застосування інсуліну (в 1922 р.) смертність від цього ускладнення сягала 100 %. Широке впровадження в практику інсулінотерапії знизило смертність до 30 %, а з удосконаленням методів лікування, зокрема інфузійної терапії, відбулось подальше її зниження. На сьогодні рівень летальності пацієнтів із порушеннями водно-електролітного та кислотно-основного стану залишається високим (близько 5 % у спеціалізованих центрах). Тільки в США щорічно від цього ускладнення помирає близько 4000 хворих на цукровий діабет. Прогноз перебігу захворювання значно погіршується з віком, при розвитку коми та артеріальної гіпотензії. Поширеність цукрового діабету стрімко зростає і на сьогодні становить від 20 до 50 % випадків вперше виявленого захворювання в молодих людей. Порушення електролітів є частими в пацієнтів із даною патологією і можуть бути результатом зміненого розподілу електролітів, пов’язаного з індукованою гіперглікемією осмотичних зрушень рідини, або загального дефіциту, спричиненого осмотичним діурезом. Ускладнення від пошкодження органів-мішеней і методи лікування цукрового діабету можуть також сприяти електролітним порушенням. Порушення регуляції гомеостазу глюкози призводить до великої кількості прямих і непрямих впливів на електролітний і кислотно-основний баланс, оскільки велика поширеність діабету гарантує, що лікарі практично кожної спеціальності мають справу з пацієнтами, хворими на цукровий діабет, а знання, пов’язані зі змінами електролітів, є необхідними. У статті розглянуто, як впливають зміни гомеостазу глюкози при цукровому діабеті на водно-електролітний баланс та кислотно-основний стан пацієнта.

Inborn error of metabolism patients after liver transplantation: Outcomes of 35 patients over 27 years in one pediatric quaternary hospital.

Liver transplantation (LT) has been used for many years as a therapeutic option for certain inborn errors of metabolism (IEMs). Here we present one institution's 27 years of experience with LT in IEMs. Our objective is to assess the outcomes of IEM patients who have undergone LT, which we hypothesize to be generally successful for prevention of metabolic decompensation. A retrospective chart review was performed on patients with urea cycle defects, organic acidemias, and amino acidopathies who underwent LT at the Children's Hospital of Philadelphia. Thirty-five patients with the following conditions have undergone LT: tyrosinemia (8), methylmalonic acidemia (7), maple syrup urine disease (6), citrullinemia (6), ornithine transcarbamylase deficiency (4), propionic acidemia (2), and argininosuccinate lyase deficiency (2). Average age at transplantation was 3.6 years. Three patients are now deceased. One patient suffered a metabolic stroke posttransplant. No episodes of metabolic decompensation have been noted. Thirty-five patients received LT with generally favorable outcome. None sustained metabolic decompensation posttransplant. As has been reported previously, LT does not ameliorate pre-existing developmental differences or risk to other organ systems. Further research is needed to aid in standardization of care and follow-up, as most patients no longer follow with a geneticist.

Anthropometrics, Dietary Intake and Body Composition in Urea Cycle Disorders and Branched Chain Organic Acidemias: A Case Study of 18 Adults on Low-Protein Diets.

Low-protein diets (LPDs) are the mainstream treatment for inborn errors of intermediary protein metabolism (IEIPM), but dietary management differs worldwide. Most studies have investigated pediatric populations and their goals such as growth and metabolic balance, showing a tendency toward increasing overweight and obesity. Only a few studies have examined nutritional status and dietary intake of adult IEIPM patients on LPDs. We assessed nutritional parameters (dietary intake using a 7-day food diary record, body composition by bioimpedance analysis, and biochemical serum values) in a group of 18 adult patients with urea cycle disorders (UCDs) and branched chain organic acidemia (BCOA). Mean total protein intake was 0.61 ± 0.2 g/kg/day (73.5% of WHO Safe Levels) and mean natural protein (PN) intake was 0.54 ± 0.2 g/kg/day; 33.3% of patients consumed amino acid (AA) supplements. A totally of 39% of individuals presented a body mass index (BMI) > 25 kg/m2 and patients on AA supplements had a mean BMI indicative of overweight. All patients reported low physical activity levels. Total energy intake was 24.2 ± 5 kcal/kg/day, representing 72.1% of mean total energy expenditure estimated by predictive formulas. The protein energy ratio (P:E) was, on average, 2.22 g/100 kcal/day. Plasmatic levels of albumin, amino acids, and lipid profiles exhibited normal ranges. Phase angle (PA) was, on average, 6.0° ± 0.9°. Fat mass percentage (FM%) was 22% ± 9% in men and 36% ± 4% in women. FM% was inversely and significantly related to total and natural protein intake. Data from IEIPM adults on LPDs confirmed the pediatric trend of increasing overweight and obesity despite a low energy intake. A low protein intake may contribute to an increased fat mass. Nutritional parameters and a healthy lifestyle should be routinely assessed in order to optimize nutritional status and possibly reduce risk of cardiovascular degenerative diseases in adult UCD and BCOA patients on LPDs.

High-risk phenotypes of genetic disease in a Neonatal Intensive Care Unit population.

High-risk phenotypes of genetic disease in a Neonatal Intensive Care Unit population.

Standardizing genetic and metabolic consults for non-accidental trauma at a large pediatric academic center

BackgroundEvaluations of suspected non-accidental trauma (NAT) often include consultation with genetic and metabolic teams to assess patients for rare genetic conditions that can mimic or exacerbate child abuse. Diagnoses that may be questioned during court proceedings include osteogenesis imperfecta (OI) and glutaric aciduria type 1 (GA1). Currently there are no official society guidelines for the genetic or metabolic workup of suspected NAT. ObjectiveTo standardize consult recommendations for suspected NAT through collaboration between the Genetics and Genomics Division and the Child Protection Team (CPT). Participants and settingsChildren evaluated for suspected NAT at a single pediatric referral center. MethodsA year of inpatient consult requests for suspected NAT to the genetics division were reviewed. The most common indications for consult were fractures and subdural hematoma. Consult recommendations for similar indications varied between providers. A standard operating procedure (SOP) with specific recommendations for suspected NAT consults for fractures, intracranial hemorrhage, and other indications was created based on expert reviews and other relevant literature. A questionnaire assessing division practice patterns for these consults was distributed both pre (n = 17) and post-introduction of the SOP (n = 11). ResultsAdherence to the SOP and impact on suspected NAT consult recommendations were assessed at 18 months after SOP introduction. Consult recommendations were in line with the SOP for 7/11 consults pre-intervention and 6/7 consults post-intervention. Providers were more likely to report feeling extremely or very confident they were using evidence-based medicine for NAT consults post-intervention.

Neonatal genetic metabolic disease entities ought to be included in tandem mass spectrometry screening in China

Objective To systematically retrieve and sort out the information on neonatal genetic metabolic disease entities included in tandem mass spectrometry (MS/MS) screening in some countries and to provide a reference for entity expansion in the screening on neonatal genetic metabolic diseases with MS/MS in China. Methods With literature analysis and expert consultation, we assessed the priority order of the neonatal genetic metabolic diseases to be included in screening with MS/MS using a comprehensive score. Results Totally 53 neonatal genetic metabolic diseases were identified with the practicability of to be screened with MS/MS; of which, 23, 16, and 14 were aminoacidopathies, organic acidemias and fatty amino acid metabolic diseases, respectively. The diseases with top ten comprehensive scores in descending order are isovaleric acidemia, glutaric acidemia type Ⅰ, medium-chain acyl-CoA dehydrogenase deficiency, maple syrup urine disease, homocystinuria, propionic acidemia, methyl malonic acidemia, phenylketonuria, citrullinemia type Ⅰ, and very long-chain acyl-CoA dehydrogenase deficiency. Conclusion Based on the study results, we recommend that the ten neonatal genetic metabolic diseases with higher comprehensive scores ought to be included in MS/MS screening and the subsequent disease entities for the screening could be adjusted timely according to screening detection outcomes and the incidences of neonatal genetic metabolic diseases.

Current understanding and progress of research on isovaleric acidemia

Isovaleric acidemia is a type of organic acidemia for which the earliest definite diagnosis was attained. It features an autosomal recessive inheritance, with the onset of age varying from newborn to adulthood. The clinical manifestations are complex and variable, which include feeding difficulty, vomiting, lethargy, coma, metabolic acidosis, sweaty feet odor and mental retardation. The mortality and mobility rates of isovaleric acidemia are quite high, and early diagnosis and rational treatment can significantly improve the prognosis. This article has provided a summary for the current understanding and research progress on isovaleric acidemia.

Obituary for Charles Rider Roe, MD

Early in his career at Duke University, Charlie pioneered the development and application of creatine phosphokinase isoenzymes and creatine kinase myocardial band analysis for cardiac injury. His interest in isoenzymes in Reye syndrome led him to sabbatical studies of organic acidurias at the Medical Research Council with Alec Lawson and Ron Chalmers. Upon returning to Duke, he created the Mass Spectrometry Facility with David Millington. This led to the discovery of propionylcarnitine in methylmalonic acidemia and propionic acidemia and many other disease-specific acylcarnitines. He also helped to pioneer the application of tandem mass spectrometry to newborn screening. He recruited other geneticists (Y-T Chen, SG Kahler) and genetic counselors, who together created a medical genetics training program. He collaborated with scientists and trainees from around the world. Work with Henri Brunengraber and others began the development of triheptanoin as a truly new therapy for long-chain fatty acid disorders. When he left Duke in 1995 to direct the Summers Metabolic Institute he concentrated on his work with triheptanoin, and expanded newborn screening. He was a member of numerous scientific societies and support organizations for fatty acid disorders and organic acidemias. He is survived by his wife Diane, five children from two marriages, and eight grandchildren.

Altered immune response in organic acidemia.

Most patients with organic acidemia suffer from recurrent infections. Although neutropenia has been reported in multiple studies, other components of the immune system have not been evaluated thoroughly. This study was conducted to assess the immune status of patients with organic acidemia (OA). Thirty-three patients with OA who were followed up in Istanbul University-Cerrahpasa, Cerrahpasa School of Medicine, Nutrition and Metabolism Department and a total of 32 age- and sex-matched healthy controls were enrolled to the study. The demographic and clinical data were recorded retrospectively from patient files. Complete blood counts, immunoglobulins, and lymphocyte immunophenotyping were recorded prospectively in a symptom- (infection-) free period. Of the 33 patients enrolled to the study, 21 (88%) were diagnosed with methylmalonic acidemia, 10 (33%) with propionic acidemia, and two (6.6%) with isovaleric acidemia. The mean age of the patients with OA and healthy subjects were 5.89 ± 4.11 years and 5.34 ± 4.36, respectively (P = 0.602). Twenty-nine (88%) of the patients had experienced frequent hospital admission, 13 (39%) were admitted to pediatric intensive care unit, and 18 (55%) suffered from sepsis. Naïve helper T cells and recent thymic emigrants were significantly lower in OAs (P < 0.001). Various defects in humoral immunity have also been documented including memory B cells and immunoglobulins. Patients with OAs may show adaptive immune defects rendering them susceptible to infections. Metabolic reprogramming based on nutritional modifications may be a promising therapeutic option in the future.

Tandem Mass Spectrometry for the Analysis of Plasma/Serum Acylcarnitines for the Diagnosis of Certain Organic Acidurias and Fatty Acid Oxidation Disorders.

Acylcarnitines are formed in the mitochondria by esterification between carnitine and acyl-CoAs. This occurs enzymatically via carnitine acyltransferases. Specific acylcarnitines accumulate as a result of various organic acidurias and fatty acid oxidation disorders, and, thus, acylcarnitines profiles are used for the diagnosis of these disorders. Acylcarnitines monitoring can also be used for the follow-up of patients with these disorders. Tandem mass spectrometry (MS/MS) is the most commonly used method for the analysis of acylcarnitines. An MS/MS method for the quantification of a number of acylcarnitines is described. The method involves butylation of acylcarnitines using acidified butanol. Butylated acylcarnitines are analyzed using flow injection and precursor ion scan. Multiple-reaction monitoring (MRM) is used for the analysis of low-molecular-weight acylcarnitines.

Screening of Organic Acidurias by Gas Chromatography-Mass Spectrometry (GC-MS).

Organic acidurias or acidemias are a group of diverse disorders caused by decreased or diminished activity of specific enzyme or transporter involved in the metabolism of amino acids, carbohydrates, fatty acids, and nucleic acids. Organic acidurias are generally inherited but may be acquired due to deficiency of certain cofactors or vitamins. As clinical symptoms are of nonspecific nature, definitive diagnosis of organic aciduria requires measurement of organic acids in urine or blood and sometimes enzyme activity in the cells. Gas chromatography-mass spectrometry (GC-MS) is a commonly used method for screening of organic acidurias.GC-MS procedure described here involves the use of urine volume that contains 1 μmole (113μg) of creatinine. Internal standards (tropic and 2-ketocaproic acids) are added to the samples, followed by treatment with hydroxylamine to form oxime derivatives of the ketoacids. The mixture is then acidified, and organic acids are extracted in ethyl acetate. The organic extract is concentrated to dryness, and the residue is treated with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA)/trimethylchlorosilane (TMCS)/pyridine to form the trimethylsilyl (TMS) derivatives of the organic acids. The derivatized extract is then directly injected onto GC-MS for analysis.