Multiple Acyl-CoA Dehydrogenase Deficiency: Phenotypic and Genetic Features of a Malaysian Cohort.

BACKGROUND AND PURPOSE: Multiple acyl-CoA dehydrogenase deficiency (MADD) is an inherited disorder of fatty acid oxidation that causes lipid storage myopathy (LSM). This is the first report on MADD that describes the phenotypic and genetic features of a Malaysian cohort. METHODS: Among the >2,500 patients in a local muscle biopsy database, patients with LSM were identified and their genomic DNA were extracted from muscle samples and peripheral blood. All 13 exons of the electron-transfer flavoprotein dehydrogenase gene (ETFDH) were subsequently sequenced. Fifty controls were included to determine the prevalence of identified mutations in the normal population. RESULTS: Fourteen (82%) of the 17 LSM patients had MADD with ETFDH mutations. Twelve (86%) were Chinese and two were Malay sisters. Other unrelated patients reported that they had no relevant family history. Nine (64%) were females. The median age at onset was 18.5 years (interquartile range=16-37 years). All 14 demonstrated proximal limb weakness, elevated serum creatine kinase levels, and myopathic changes in electromyography. Three patients experienced a metabolic crisis at their presentation. Sanger sequencing of ETFDH revealed nine different variants/mutations, one of which was novel: c.998A>G (p.Y333C) in exon 9. Notably, 12 (86%) patients, including the 2 Malay sisters, carried a common c.250G>A (p.A84T) variant, consistent with the hotspot mutation reported in southern China. All of the patients responded well to riboflavin therapy. CONCLUSIONS: Most of our Malaysian cohort with LSM had late-onset, riboflavin-responsive MADD with ETFDH mutations, and they demonstrated phenotypic and genetic features similar to those of cases reported in southern China. Furthermore, we report a novel ETFDH mutation and possibly the first ever MADD patients of Malay descent.

A compound heterozygote case of glutaric aciduria type II in a patient carrying a novel candidate variant in ETFDH gene: A case report and literature review on compound heterozygote cases.

BACKGROUND: Glutaric aciduria type II (GA2) is a rare genetic disorder inherited in an autosomal recessive manner. Double dosage mutations in GA2 corresponding genes, ETFDH, ETFA, and ETFB, lead to defects in the catabolism of fatty acids, and amino acids lead to broad-spectrum phenotypes, including muscle weakness, developmental delay, and seizures. product of these three genes have crucial role in transferring electrons to the electron transport chain (ETC), but are not directly involve in ETC complexes. METHODS: Here, by using exome sequencing, the cause of periodic cryptic gastrointestinal complications in a 19-year-old girl was resolved after years of diagnostic odyssey. Protein modeling for the novel variant served as another line of validation for it. RESULTS: Exome Sequencing (ES) identified two variants in ETFDH: ETFDH:c.926T>G and ETFDH:c.1141G>C. These variants are likely contributing to the crisis in this case. To the best of our knowledge at the time of writing this manuscript, variant ETFDH:c.926T>G is reported here for the first time. Clinical manifestations of the case and pathological analysis are in consistent with molecular findings. Protein modeling provided another line of evidence proving the pathogenicity of the novel variant. ETFDH:c.926T>G is reported here for the first time in relation to the causation GA2. CONCLUSION: Given the milder symptoms in this case, a review of GA2 cases caused by compound heterozygous mutations was conducted, highlighting the range of symptoms observed in these patients, from mild fatigue to more severe outcomes. The results underscore the importance of comprehensive genetic analysis in elucidating the spectrum of clinical presentations in GA2 and guiding personalized treatment strategies.

Dried Blood Spot Postmortem Metabolic Autopsy With Genotype Validation for Sudden Unexpected Deaths in Infancy and Childhood in Hong Kong.

Background Inborn errors of metabolism (IEM) are collectively rare but potentially preventable causes of sudden unexpected death (SUD) in infancy or childhood, and metabolic autopsy serves as the final tool for establishing the diagnosis. We conducted a retrospective review of the metabolic and molecular autopsy on SUD and characterized the biochemical and genetic findings. Methodology A retrospective review of postmortem metabolic investigations (dried blood spot acylcarnitines and amino acid analysis, urine metabolic profiling where available, and next-generation sequencing on a panel of 75 IEM genes) performed for infants and children who presented with SUD between October 2016 and December 2021 with inconclusive autopsy findings or autopsy features suspicious of underlying IEM in our locality was conducted. Clinical and autopsy findings were reviewed for each case. Results A total of 43 infants and children aged between zero days to 10 years at the time of death were referred to the authors' laboratories throughout the study period. One positive case of multiple acyl-CoA dehydrogenase deficiency was diagnosed. Postmortem reference intervals for dried blood spot amino acids and acylcarnitines profile were established based on the results from the remaining patients. Conclusions Our study confirmed the importance of metabolic autopsy and the advantages of incorporating biochemical and genetic testing in this setting.

Efficacy and Safety of Coenzyme Q10 Supplementation in Neonates, Infants and Children: An Overview.

To date, there have been no review articles specifically relating to the general efficacy and safety of coenzyme Q10 (CoQ10) supplementation in younger subjects. In this article, we therefore reviewed the efficacy and safety of CoQ10 supplementation in neonates (less than 1 month of age), infants (up to 1 year of age) and children (up to 12 years of age). As there is no rationale for the supplementation of CoQ10 in normal younger subjects (as there is in otherwise healthy older subjects), all of the articles in the medical literature reviewed in the present article therefore refer to the supplementation of CoQ10 in younger subjects with a variety of clinical disorders; these include primary CoQ10 deficiency, acyl CoA dehydrogenase deficiency, Duchenne muscular dystrophy, migraine, Down syndrome, ADHD, idiopathic cardiomyopathy and Friedreich's ataxia.

Management and Outcomes of Very Long-Chain Acyl-CoA Dehydrogenase Deficiency (VLCAD Deficiency): A Retrospective Chart Review.

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a rare genetic condition affecting the mitochondrial beta-oxidation of long-chain fatty acids. This study reports on the clinical outcomes of patients diagnosed by newborn screening with VLCAD deficiency comparing metabolic parameters, enzyme activities, molecular results, and clinical management. It is a single-center retrospective chart review of VLCAD deficiency patients who met the inclusion criteria between January 2002 and February 2020. The study included 12 patients, 7 of whom had an enzyme activity of more than 10%, and 5 patients had an enzyme activity of less than 10%. The Pearson correlation between enzyme activity and the C14:1 level at newborn screening showed a p-value of 0.0003, and the correlation between enzyme activity and the C14:1 level at diagnosis had a p-value of 0.0295. There was no clear correlation between the number of documented admissions and the enzyme activity level. Patients who had a high C14:1 value at diagnosis were started on a diet with a lower percentage of energy from long-chain triglycerides. The C14:1 result at diagnosis is the value that has been guiding our initial clinical management in asymptomatic diagnosed newborns. However, the newborn screening C14:1 value is the most sensitive predictor of low enzyme activity and may help guide dietary management.

Navigating the Diagnostic Journey in Pediatric Gastroenterology: Decoding Recurrent Vomiting and Epigastric Pain in a Child with Glutaric Aciduria Type II.

BACKGROUND: Glutaric aciduria type II (GA II), also known as multiple acyl-CoA dehydrogenase deficiency (MADD), is a rare autosomal recessive metabolic disorder with varied manifestations and onset ages. CASE REPORT: This study presents a distinctive case of a 10-year-old girl who experienced episodic, intermittent vomiting and epigastric pain, particularly aggravated by high-fat and sweet foods. Despite inconclusive physical examinations and routine laboratory tests, and an initial suspicion of cyclic vomiting syndrome, the persistence of recurrent symptoms and metabolic abnormalities (metabolic acidosis and hypoglycemia) during her third hospital admission necessitated further investigation. Advanced diagnostic tests, including urinary organic acid analysis and genetic testing, identified heterozygous pathogenic variants in the ETFDH gene, confirming a diagnosis of GA IIc. The patient showed a positive response to a custom low-protein, low-fat diet supplemented with carnitine and riboflavin. SIGNIFICANCE: This case emphasizes the diagnostic challenges associated with recurrent, nonspecific gastrointestinal symptoms in pediatric patients, particularly in differentiating between common gastrointestinal disorders and rare metabolic disorders like GA II. It highlights the importance of considering a broad differential diagnosis to enhance understanding and guide future medical approaches in similar cases.

Stealthy progression of type 2 diabetes mellitus due to impaired ketone production in an adult patient with multiple acyl-CoA dehydrogenase deficiency.

Background: Multiple acyl-CoA dehydrogenase deficiency (MADD) is an inherited metabolic disorder caused by biallelic pathogenic variants in genes related to the flavoprotein complex. Dysfunction of the complex leads to impaired fatty acid oxidation and ketone body production which can cause hypoketotic hypoglycemia with prolonged fasting. Patients with fatty acid oxidation disorders (FAODs) such as MADD are treated primarily with a dietary regimen consisting of high-carbohydrate foods and avoidance of prolonged fasting. However, information on the long-term sequelae associated with this diet have not been accumulated. In general, high-carbohydrate diets can induce diseases such as type 2 diabetes mellitus (T2DM), although few patients with both MADD and T2DM have been reported. Case: We present the case of a 32-year-old man with MADD who was on a high-carbohydrate diet for >30 years and exhibited symptoms resembling diabetic ketoacidosis. He presented with polydipsia, polyuria, and weight loss with a decrease in body mass index from 31 to 25 kg/m2 over 2 months. Laboratory tests revealed a HbA1c level of 13.9%; however, the patient did not show metabolic acidosis but only mild ketosis. Discussion/conclusion: This report emphasizes the potential association between long-term adherence to high-carbohydrate dietary therapy and T2DM development. Moreover, this case underscores the difficulty of detecting diabetic ketosis in patients with FAODs such as MADD due to their inability to produce ketone bodies. These findings warrant further research of the long-term complications associated with this diet as well as warning of the potential progression of diabetes in patients with FAODs such as MADD.

Hip Dysplasia in a Patient in Late Adolescence With Charcot-Marie-Tooth and Multiple Acyl-CoA Dehydrogenase Deficiency.

This case report explores a unique presentation of hip dysplasia in a female patient aged 21 years old diagnosed with Charcot-Marie-Tooth disease (CMT) type 1A and multiple acyl-CoA dehydrogenase deficiency (MADD). The coexistence of these neuromuscular and metabolic disorders in a patient with hip dysplasia provides an opportunity to investigate their potential interactions and impact on diagnosis, treatment, and prognosis. The patient underwent labral repair with shelf osteotomy and later a total hip replacement. This case highlights the need for further research to better understand the relationships between CMT, MADD, neuromuscular dysplasia, and hip dysplasia. A deeper understanding of these interactions may lead to improved diagnostic techniques, earlier intervention, and personalized treatment approaches for patients with co-morbid conditions, ultimately improving patient outcomes and reducing complications later in life.

Plasma lipidomics analysis reveals altered profile of triglycerides and phospholipids in children with Medium-Chain Acyl-CoA dehydrogenase deficiency.

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is the most prevalent mitochondrial fatty acid ß-oxidation disorder. In this study, we assessed the variability of the lipid profile in MCADD by analysing plasma samples obtained from 25 children with metabolically controlled MCADD (following a normal diet with frequent feeding and under l-carnitine supplementation) and 21 paediatric control subjects (CT). Gas chromatography-mass spectrometry was employed for the analysis of esterified fatty acids, while high-resolution C18-liquid chromatography-mass spectrometry was used to analyse lipid species. We identified a total of 251 lipid species belonging to 15 distinct lipid classes. Principal component analysis revealed a clear distinction between the MCADD and CT groups. Univariate analysis demonstrated that 126 lipid species exhibited significant differences between the two groups. The lipid species that displayed the most pronounced variations included triacylglycerols and phosphatidylcholines containing saturated and monounsaturated fatty acids, specifically C14:0 and C16:0, which were found to be more abundant in MCADD. The observed changes in the plasma lipidome of children with non-decompensated MCADD suggest an underlying alteration in lipid metabolism. Therefore, longitudinal monitoring and further in-depth investigations are warranted to better understand whether such alterations are specific to MCADD children and their potential long-term impacts.

The male-to-female ratio in late-onset multiple acyl-CoA dehydrogenase deficiency: a systematic review and meta-analysis.

BACKGROUND: Late-onset multiple acyl-CoA dehydrogenase deficiency (MADD) is the most common lipid storage myopathy. There are sex differences in fat metabolism and it is not known whether late-onset MADD affects men and women equally. METHODS: In this systematic review and meta-analysis, the PubMed, Embase, Web of Science, CNKI, CBM, and Wanfang databases were searched until 01/08/2023. Studies reporting sex distribution in patients with late-onset MADD were included. Two authors independently screened studies for eligibility, extracted data, and assessed risk of bias. Pre-specified outcomes of interest were the male-to-female ratio (MFR) of patients with late-onset MADD, the differences of clinical characteristics between the sexes, and factors influencing the MFR. RESULTS: Of 3379 identified studies, 34 met inclusion criteria, yielding a total of 609 late-onset MADD patients. The overall pooled percentage of males was 58% (95% CI, 54-63%) with low heterogeneity across studies (I2 = 2.99%; P = 0.42). The mean onset ages, diagnostic delay, serum creatine kinase (CK), and allelic frequencies of 3 hotspot variants in ETFDH gene were similar between male and female patients (P > 0.05). Meta-regressions revealed that ethnic group was associated with the MFR in late-onset MADD, and subgroup meta-analyses demonstrated that East-Asian patients had a higher percentage of male, lower CK, and higher proportion of hotspot variants in ETFDH gene than non-East-Asian patients (P < 0.05). CONCLUSIONS: Male patients with late-onset MADD were more common than female patients. Ethnicity was proved to be a factor influencing the MFR in late-onset MADD. These findings suggest that male sex may be a risk factor for the disease.

The presence of white cell Jordan's anomaly in multiple Acyl-CoA dehydrogenase deficiency: A case report and implications for clinical practice.

BACKGROUND: Multiple Acyl-CoA Dehydrogenase Deficiency (MADD), also known as Glutaric Aciduria Type II, is an exceptionally rare autosomal recessive genetic disorder that disrupts the metabolism of fatty acids, amino acids, and choline. It presents with a wide range of clinical manifestations, from severe neonatal-onset forms to milder late-onset cases, with symptoms including metabolic disturbances and muscle weakness. Jordan's anomaly is a distinctive morphological feature found in peripheral blood white cells and is typically associated with Neutral Lipid Storage Disease (NLSD). CASE REPORT: In our case report, the patient initially presented with symptoms of vomiting, abdominal pain, and altered consciousness. The presence of white cell Jordan's anomaly was detected in the blood smear. Subsequent serum tests revealed elevated levels of transaminases, creatine kinase, uric acid, and multiple acylcarnitines, while blood glucose and free carnitine levels were notably reduced. High-throughput sequencing confirmed heterozygous pathogenic variants in the electron-transferring flavoprotein dehydrogenase (ETFDH) gene, leading to the conclusive diagnosis of MADD. Following a three-month treatment regimen involving high-dose vitamin B2, coenzyme Q10, and other supportive interventions, the patient exhibited significant clinical improvement, ultimately resulting in discharge. CONCLUSION: The identification of Jordan's anomaly in a pediatric patient with late-onset MADD sheds light on its broader implications within the realm of lipid storage myopathies. The significance of this finding extends beyond its conventional association with NLSD, challenging the notion of its exclusivity. This novel observation serves as a compelling reminder of the diagnostic significance this morphological abnormality holds, potentially revolutionizing diagnostic practices within the field.

Newborn screening for fatty acid oxidation disorders in a southern Chinese population.

Background and aims: Fatty acid oxidation disorders (FAODs) are a group of autosomal recessive metabolic diseases included in many newborn screening (NBS) programs, but the incidence and disease spectrum vary widely between ethnic groups. We aimed to elucidate the incidence, disease spectrum, and genetic features of FAODs in a southern Chinese population. Materials and methods: The FAODs screening results of 643,606 newborns from 2014 to 2022 were analyzed. Results: Ninety-two patients were eventually diagnosed with FAODs, of which 61 were PCD, 20 were MADD, 5 were SCADD, 4 were VLCADD, and 2 were CPT-IAD. The overall incidence of FAODs was 1:6996 (95 % CI: 1:5814-1:8772) newborns. All PCD patients had low C0 levels during NBS, while nine patients (14.8 %) had normal C0 levels during the recall review. All but one MADD patients had elevated C8, C10, and C12 levels during NBS, while eight patients (40 %) had normal acylcarnitine levels during the recall review. The most frequent SLC22A5 variant was c.760C > T (p.R254*) with an allele frequency of 29.51 %, followed by c.51C > G (p.F17L) (17.21 %) and c.1400C > G (p.S467C) (16.39 %). The most frequent ETFDH variant was c.250G > A (p.A84T) with an allelic frequency of 47.5 %, followed by c.524G > A (R175H) (12.5 %), c.998A > G (p.Y333C) (12.5 %), and c.1657T > C (p.Y553H) (7.5 %). Conclusion: The prevalence, disease spectrum, and genetic characteristics of FAODs in a southern Chinese population were clarified. PCD was the most common FAOD, followed by MADD. Hotspot variants were found in SLC22A5 and ETFDH genes, while the remaining FAODs showed great molecular heterogeneity. Incorporating second-tier genetic screening is critical for FAODs.

Clinical, biochemical, and genetic spectrum of MADD in a South African cohort: an ICGNMD study.

BACKGROUND: Multiple acyl-CoA dehydrogenase deficiency (MADD) is an autosomal recessive disorder resulting from pathogenic variants in three distinct genes, with most of the variants occurring in the electron transfer flavoprotein-ubiquinone oxidoreductase gene (ETFDH). Recent evidence of potential founder variants for MADD in the South African (SA) population, initiated this extensive investigation. As part of the International Centre for Genomic Medicine in Neuromuscular Diseases study, we recruited a cohort of patients diagnosed with MADD from academic medical centres across SA over a three-year period. The aim was to extensively profile the clinical, biochemical, and genomic characteristics of MADD in this understudied population. METHODS: Clinical evaluations and whole exome sequencing were conducted on each patient. Metabolic profiling was performed before and after treatment, where possible. The recessive inheritance and phase of the variants were established via segregation analyses using Sanger sequencing. Lastly, the haplotype and allele frequencies were determined for the two main variants in the four largest SA populations. RESULTS: Twelve unrelated families (ten of White SA and two of mixed ethnicity) with clinically heterogeneous presentations in 14 affected individuals were observed, and five pathogenic ETFDH variants were identified. Based on disease severity and treatment response, three distinct groups emerged. The most severe and fatal presentations were associated with the homozygous c.[1067G > A];c.[1067G > A] and compound heterozygous c.[976G > C];c.[1067G > A] genotypes, causing MADD types I and I/II, respectively. These, along with three less severe compound heterozygous genotypes (c.[1067G > A];c.[1448C > T], c.[740G > T];c.[1448C > T], and c.[287dupA*];c.[1448C > T]), resulting in MADD types II/III, presented before the age of five years, depending on the time and maintenance of intervention. By contrast, the homozygous c.[1448C > T];c.[1448C > T] genotype, which causes MADD type III, presented later in life. Except for the type I, I/II and II cases, urinary metabolic markers for MADD improved/normalised following treatment with riboflavin and L-carnitine. Furthermore, genetic analyses of the most frequent variants (c.[1067G > A] and c.[1448C > T]) revealed a shared haplotype in the region of ETFDH, with SA population-specific allele frequencies of < 0.00067-0.00084%. CONCLUSIONS: This study reveals the first extensive genotype-phenotype profile of a MADD patient cohort from the diverse and understudied SA population. The pathogenic variants and associated variable phenotypes were characterised, which will enable early screening, genetic counselling, and patient-specific treatment of MADD in this population.

Medium Chain Acyl CoA Dehydrogenase Deficiency and Eating Disorders: An Underreported Coincidence

Abstract Medium chain acyl-coA dehydrogenase deficiency (MCADD), the most common fatty acid oxidation disorder, has been regarded as a relatively benign condition with low risk of mortality in patients with a known diagnosis, if adequate caloric intake is met. However, inadequate energy provision, as occurs in eating disorders, significantly amplifies the risk of metabolic decompensation. This case series describes four patients with MCADD and a concomitant eating disorder and aims to raise awareness of the potentially under-recognised coexistence of these conditions. All patients were female with signs of disordered eating in adolescence and young adulthood though latency in diagnosis was apparent. Three of the patients had low body mass index (BMI) and the other was overweight. Metabolic decompensation and hospitalisation occurred in three of four patients secondary to extreme risk-taking behaviour with caloric restriction. The coexistence of MCADD and eating disorders is of significant concern, placing the patient at substantial risk of decompensation in an otherwise relatively stable metabolic condition. Awareness of disordered eating in this population is paramount, as early recognition of signs and symptoms of eating disorders in the MCADD population may facilitate prompt intervention and avoidance of morbidity and potential mortality.

The First Reported Case of a Child with Two Different Rare Metabolic Disorders: Very Long-Chain Acyl-CoA Dehydrogenase Deficiency and Encephalomyopathic Mitochondrial DNA Depletion Syndrome 13.

One of the most common inborn errors in fatty acid ß oxidation (FAO) is a very long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency. It is autosomal recessive. The enzyme used in the first phase of FAO is VLCAD. The enzyme is responsible for ß oxidation spiral pathway's initial step, the dehydrogenation process of long-chain fatty acyl-CoA. The phenotypes include hypoglycemia, hepatomegaly, cardiomyopathy, and occasionally abrupt mortality. Most VLCAD deficiencies in newborns are now detected during the neonatal period due to the development of newborn screening programs. Mitochondrial DNA depletion syndromes (MTDPS) are one of the rarest metabolic disorders. It is an autosomal recessive disease caused by defects in genes necessary for the maintenance of mitochondrial DNA (mtDNA). One of these FBXL4 (F-box and leucine-rich repeat protein 4) variants causes encephalomyopathic mtDNA depletion syndrome 13 (MTDPS13), which presents as a failure to thrive, severe global developmental delay, hypotonia, early infantile onset of encephalopathy, and lactic acidosis. We report here the case of a Saudi infant born to consanguineous parents who presented to us with severe failure to thrive, profound neurodevelopmental delays, and facial dysmorphic features. Whole-exome sequencing (WES) showed the infants had MTDPS13. The FBXL4 variant c.1698A > G p. (Ile566Met) has previously been described as a disease that causes developmental delay and lactic acidosis, and another variant has also been detected in the patient. The ACADVL variant c.134C > A p. (Ser45*) has previously been described to cause VLCAD deficiency. A comprehensive literature review showed our patient to be the first case of MTDPS13 and VLCAD reported to date worldwide.

[A case of very long chain acyl-CoA dehydrogenase deficiency diagnosed due to a trigger of hyperemesis gravidarum during pregnancy].

A 25-year-old Japanese woman with a history of repeated episodes of rhabdomyolysis since the age of 12 presented with rhabdomyolysis caused by hyperemesis gravidarum. Blood tests showed an elevated serum CK level (11,755 |IU/l; normal: 30-180 |IU/l). Carnitine fractionation analysis revealed low levels of total carnitine (18.3 |µmol/l; normal: 45-91 |µmol/l), free carnitine (13.1 |µmol/l; normal: 36-74 |µmol/l), and acylcarnitine (5.2 |µmol/l; normal: 6-23 |µmol/l). Tandem mass spectrometry showed high levels of C14:1 acylcarnitine (0.84 |nmol/ml: normal: <0.4 |nmol/ml) and a high C14:1/C2 ratio of 0.253 (normal: <0.013), indicating a potential diagnosis of very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Enzyme activity measurement in the patient's peripheral blood lymphocytes confirmed the diagnosis of VLCAD deficiency, with low palmitoyl-CoA dehydrogenase levels (6.5% of normal control value). With the patient's informed consent, acyl-CoA dehydrogenase very long-chain (ACADVL) gene analysis revealed compound heterozygous mutations of c.1332G>A in exon 13 and c.1349G>A (p.R450H) in exon 14. In Japan, neonatal mass screening is performed to detect congenital metabolic diseases. With the introduction of tandem mass screening in 2014, fatty acid metabolism disorders, including VLCAD deficiency, are being detected before the onset of symptoms. However, it is important to note that mass screening cannot detect all cases of this disease. For patients with recurrent rhabdomyolysis, it is essential to consider congenital diseases, including fatty acid metabolism disorders, as a potential diagnosis.

Personalised modelling of clinical heterogeneity between medium-chain acyl-CoA dehydrogenase patients.

BACKGROUND: Monogenetic inborn errors of metabolism cause a wide phenotypic heterogeneity that may even differ between family members carrying the same genetic variant. Computational modelling of metabolic networks may identify putative sources of this inter-patient heterogeneity. Here, we mainly focus on medium-chain acyl-CoA dehydrogenase deficiency (MCADD), the most common inborn error of the mitochondrial fatty acid oxidation (mFAO). It is an enigma why some MCADD patients-if untreated-are at risk to develop severe metabolic decompensations, whereas others remain asymptomatic throughout life. We hypothesised that an ability to maintain an increased free mitochondrial CoA (CoASH) and pathway flux might distinguish asymptomatic from symptomatic patients. RESULTS: We built and experimentally validated, for the first time, a kinetic model of the human liver mFAO. Metabolites were partitioned according to their water solubility between the bulk aqueous matrix and the inner membrane. Enzymes are also either membrane-bound or in the matrix. This metabolite partitioning is a novel model attribute and improved predictions. MCADD substantially reduced pathway flux and CoASH, the latter due to the sequestration of CoA as medium-chain acyl-CoA esters. Analysis of urine from MCADD patients obtained during a metabolic decompensation showed an accumulation of medium- and short-chain acylcarnitines, just like the acyl-CoA pool in the MCADD model. The model suggested some rescues that increased flux and CoASH, notably increasing short-chain acyl-CoA dehydrogenase (SCAD) levels. Proteome analysis of MCADD patient-derived fibroblasts indeed revealed elevated levels of SCAD in a patient with a clinically asymptomatic state. This is a rescue for MCADD that has not been explored before. Personalised models based on these proteomics data confirmed an increased pathway flux and CoASH in the model of an asymptomatic patient compared to those of symptomatic MCADD patients. CONCLUSIONS: We present a detailed, validated kinetic model of mFAO in human liver, with solubility-dependent metabolite partitioning. Personalised modelling of individual patients provides a novel explanation for phenotypic heterogeneity among MCADD patients. Further development of personalised metabolic models is a promising direction to improve individualised risk assessment, management and monitoring for inborn errors of metabolism.

Case report: Diagnosis of a patient with Sifrim-Hitz-Weiss syndrome, development and epileptic encephalopathy-14, and medium chain acyl-CoA dehydrogenase deficiency.

Background: It is generally recognized that genetic metabolic disorders can result in neurological symptoms such as seizures, developmental delay, and intellectual disability. Heterogeneous clinical presentations make the diagnosis challenging. Case presentation: In this case report, we present a unique and complex genetic disorder observed in a female patient who exhibited three pathogenic gene variants in the KCNT1, ACADM, and CHD4 genes. The convergence of these variants resulted in a multifaceted clinical presentation characterized by severe seizures of combined focal and generalized onset, metabolic dysfunction, and neurodevelopmental abnormalities. The identification and functional characterization of these gene variants shed light on the intricate interplay between these genes and the patient's phenotype. EEG revealed an epileptiform abnormality which presented in the inter-ictal period from the left frontal-central area and in the ictal period from the left mid-temporal area. The brain MRI revealed volume loss in the posterior periventricular area and parietal parenchyma, myelin destruction with no sign of hypoxic involvement, and left dominant enlargement of the lateral ventricles secondary to loss of central parenchyma. The patient was diagnosed through exome sequencing with Sifrim-Hitz-Weiss syndrome, development and epileptic encephalopathy-14, and medium-chain acyl-CoA dehydrogenase deficiency. An antiseizure medication regimen with valproic acid, levetiracetam, phenobarbital, and clonazepam was initiated. However, this led to only partial control of the seizures. Conclusion: Clinical follow-up of the patient will further define the clinical spectrum of KCNT1, ACADM, and CHD4 gene variants. It will also determine the long-term efficacy of the treatment of seizures and the development of precision medicine for epilepsy syndromes due to gain-of-function variants. Special emphasis should be put on the role and importance of large-scale genomic testing in understanding and diagnosing complex phenotypes and atypical epileptic syndromes.

"Liver Failure in an Infant of Late-Onset Glutaric Aciduria Type II": Case Report.

Glutaric aciduria type II, also known as Multiple acyl-CoA Dehydrogenase Deficiency, results from a defect in the mitochondrial electron transport chain resulting in an inability to break down fatty-acids and amino acids. There are three phenotypes- type 1 and 2 are of neonatal onset and severe form, with and without congenital anomalies, respectively, and presents with acidosis, severe hypotonia, cardiomyopathy, hepatomegaly, and non-ketotic hypoglycemia. Type 3 or late-onset Multiple acyl-CoA Dehydrogenase Deficiency usually presents in the adolescent or adult age group with phenotype ranging from mild forms of myopathy and exercise intolerance to severe forms of acute metabolic decompensation on its chronic course. Type 3 Multiple acyl-CoA Dehydrogenase Deficiency rarely presents in infancy and in liver failure. We present a five-month-old developmentally normal female child with acute encephalopathy, hypotonia, non-ketotic hypoglycemia, metabolic acidosis, and liver failure, with a history of sibling death of suspected inborn error of metabolism. The blood acyl-carnitine levels in Tandem Mass Spectrometry and urinary organic acid analysis through Gas Chromatography-Mass Spectrometry were unremarkable. The patient initially responded to riboflavin, CoQ, and supportive management but ultimately succumbed to sepsis with shock and multi-organ dysfunction. The clinical exome sequencing reported a homozygous missense variation in exon 11 of the ETFDH gene (chr4:g.158706270C > T) that resulted in the amino acid substitution of Leucine for Proline at codon 456 (p.Pro456Leu) suggestive of Glutaric aciduria type IIc (OMIM#231,680).

Hyperhomocysteinemia in patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency.

INTRODUCTION/AIMS: Riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (RR-MADD) is an autosomal recessive disease chiefly caused by variants of ETFDH affecting fatty acid metabolism. In our cohort, hyperhomocysteinemia (HHcy) was common. In this study we aimed to identify the association between RR-MADD and HHcy. METHODS: We performed a retrospective review of 13 patients with RR-MADD. Thirty-three healthy controls were recruited, and logistic regression was used to investigate the association between RR-MADD and HHcy. Muscle tissues from six patients and six controls without myopathies were collected to measure the levels of flavin adenine dinucleotide (FAD), an active form of riboflavin. Whole-exome sequencing was performed to identify the disease-associated variants. RESULTS: The RR-MADD patients had a higher prevalence of HHcy (9 of 12) than controls (6 of 33, P < .001). In the multivariate analysis, RR-MADD was positively related to HHcy (P = .014). Muscular FAD levels were decreased in RR-MADD patients (P = .006). Thirteen variants (8 reported and 5 novel) were identified in ETFDH. Of these, c.250G > A was the most common pathogenic variant with an allelic frequency of 4 of 20. DISCUSSION: HHcy was associated with RR-MADD and may aid in the diagnosis of the disease. Our findings expand the mutational spectrum of RR-MADD.