Efficacy of bezafibrate for preventing myopathic attacks in patients with very long-chain acyl-CoA dehydrogenase deficiency.

BACKGROUND: Very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) is a mitochondrial fatty acid oxidation disorder that causes episodic attacks, such as general fatigue, hypotonia, myalgia, and rhabdomyolysis accompanied by lack of energy. As yet, there are no preventative drugs for these VLCADD-associated metabolic attacks. PATIENTS AND METHODS: We conducted an open-label, non-randomized, multi-center study into the effects of bezafibrate on five patients with VLCADD. Bezafibrate was administered for 4 years, and we analyzed the number of myopathic attacks requiring hospitalization and treatment infusions. RESULTS: The number of myopathic attacks requiring infusions of 24 h or longer significantly decreased during the study period. The patients' ability to conduct everyday activities was also improved by the treatment. CONCLUSION: Our findings show the potential long-term efficacy of bezafibrate in preventing myopathic attacks for patients with VLCADD.

Clinical manifestations and management of fatty acid oxidation disorders.

Fatty acid oxidation disorders (FAOD) are a group of rare, autosomal recessive, metabolic disorders caused by variants of the genes for the enzymes and proteins involved in the transport and metabolism of fatty acids in the mitochondria. Those affected by FAOD are unable to convert fatty acids into tricarboxylic acid cycle intermediates such as acetyl-coenzyme A, resulting in decreased adenosine triphosphate and glucose for use as energy in a variety of high-energy-requiring organ systems. Signs and symptoms may manifest in infants but often also appear in adolescents or adults during times of increased metabolic demand, such as fasting, physiologic stress, and prolonged exercise. Patients with FAOD present with a highly heterogeneous clinical spectrum. The most common clinical presentations include hypoketotic hypoglycemia, liver dysfunction, cardiomyopathy, rhabdomyolysis, and skeletal myopathy, as well as peripheral neuropathy and retinopathy in some subtypes. Despite efforts to detect FAOD through newborn screening and manage patients early, symptom onset can be sudden and serious, even resulting in death. Therefore, it is critical to identify quickly and accurately the key signs and symptoms of patients with FAOD to manage metabolic decompensations and prevent serious comorbidities.

Electrophysiological Abnormalities in VLCAD Deficient hiPSC-Cardiomyocytes Can Be Improved by Lowering Accumulation of Fatty Acid Oxidation Intermediates.

Patients with very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) can present with life-threatening cardiac arrhythmias. The pathophysiological mechanism is unknown. We reprogrammed fibroblasts from one mildly and one severely affected VLCADD patient, into human induced pluripotent stem cells (hiPSCs) and differentiated these into cardiomyocytes (VLCADD-CMs). VLCADD-CMs displayed shorter action potentials (APs), more delayed afterdepolarizations (DADs) and higher systolic and diastolic intracellular Ca2+ concentration ([Ca2+]i) than control CMs. The mitochondrial booster resveratrol mitigated the biochemical, electrophysiological and [Ca2+]i changes in the mild but not in the severe VLCADD-CMs. Accumulation of potentially toxic intermediates of fatty acid oxidation was blocked by substrate reduction with etomoxir. Incubation with etomoxir led to marked prolongation of AP duration and reduced DADs and [Ca2+]i in both VLCADD-CMs. These results provide compelling evidence that reduced accumulation of fatty acid oxidation intermediates, either by enhanced fatty acid oxidation flux through increased mitochondria biogenesis (resveratrol) or by inhibition of fatty acid transport into the mitochondria (etomoxir), rescues pro-arrhythmia defects in VLCADD-CMs and open doors for new treatments.

Pearson marrow-pancreas syndrome with cardiac conduction abnormality necessitating prophylactic pacemaker implantation.

Pearson marrow-pancreas syndrome (PS), an exceedingly rare mitochondrial disorder, involves multiple systems including hematologic system and pancreas. Other mitochondrial disorders have been associated with progressive infrahisian block but this has not yet been described as a major feature of PS. We report a 7-year-old girl with classical features of PS and cardiac conduction defect. Her electrocardiogram revealed QRS prolongation with right bundle and left anterior fascicular blocks. Follow-up Holter revealed bifascicular block, alternating left and right bundle branch blocks, supraventricular tachycardia (with alternating bundles), and suspicion for nonsustained ventricular tachycardia. She underwent successful transvenous single-chamber ventricular pacemaker.

Broadening the phenotypic spectrum of Pearson syndrome: Five new cases and a review of the literature.

Pearson syndrome (PS) is a multisystem mitochondrial respiratory chain disorder typically characterized by sideroblastic anemia and exocrine pancreatic insufficiency. PS is caused by a single large-scale mitochondrial DNA (mtDNA) deletion. PS classically presents in the first year of life and may be fatal in infancy. Children who survive PS may progress to develop Kearns-Sayre syndrome later in life. The full phenotypic spectrum and prognosis of the condition continue to evolve. Here we report five new patients with PS with unique clinical presentations, including four patients with onset later than previously reported in the literature, and one patient with prenatal onset of symptoms. The timing and unique features of these presentations support an expanded phenotypic spectrum of single large-scale mtDNA deletion syndromes (SLSMDS) and reinforce the importance of including SLSMDS in the differential for children with complex multisystem presentations.

Adolescent Hyperuricemia with Lipid Storage Myopathy: A Clinical Study.

BACKGROUND In this study, we investigated the clinical and pathological features of patients with lipid storage myopathy (LSM) complicated with hyperuricemia, to improve clinicians' understanding of metabolic multi-muscular disorder with metabolic disorders, and to reduce the risk of missed diagnosis of LSM. MATERIAL AND METHODS From January 2005 to December 2017, 8 patients underwent muscle biopsy and diagnosed by muscle pathology and genetic testing in our hospital. All 8 patients were in compliance with LSM diagnosis. We collected data on the patient's clinical performance, adjuvant examination, treatment, and outcomes to provide a comprehensive report and description of LSM patients with hyperuricemia. RESULTS All patients were diagnosed as having ETFDH gene mutations. The main clinical manifestations of patients were chronic limb and trunk weakness, limb numbness, and muscle pain. The serum creatine kinase (CK) values in all patients were higher than normal values. Electromyography showed 3 cases of simple myogenic damage and 3 cases of neurogenic injury. Hematuria metabolic screening showed that 2 patients had elevated glutaric aciduria, and 1 patient had elevated fatty acyl carnitine in the blood. All patients were given riboflavin treatment, and the clinical symptoms were significantly improved, and 3 patients returned to normal uric acid levels after treatment. Pathological staining showed an abnormal deposition of lipid droplets in muscle fibers. CONCLUSIONS If an adolescent hyperuricemia patient has abnormal limb weakness, exercise intolerance, and elevated serum CK values, clinicians need to be highly alert to the possibility of LSM. Early diagnosis and treatment of LSM should improve the clinical symptoms and quality of life and reduce complications.

Clinical features and genetic analysis of childhood sitosterolemia: Two case reports and literature review.

RATIONALE: Sitosterolemia is a rare autosomal recessive disorder of dyslipidemia due to mutations of genes ABCG5 and ABCG8, leading to highly elevated plasma levels of plant sterols and expanded body pools of cholesterol. PATIENT CONCERNS: We present a 9-year-old and a 7-year-old Chinese boy with hypercholesterolemia and xanthomas of sitosterolemia due to ABCG5 gene mutations. We also make a literature review of another 30 sitosterolemic children cases that have been reported with virulence ABCG5 gene mutations. DIAGNOSIS: We took peripheral blood samples from 2 patients and their parents to conduct genetic analysis by next-generation sequencing (NGS) technologies. INTERVENTIONS: The 2 patients received dietary modifications without pharmaceuticals treatment. OUTCOMES: A c.1166G>A (Arg389His) homozygosis mutation in exon 9 was observed in case 1, whereas a c.751C>T (Gln251*) homozygosis mutation in exon 6 was found in case 2. Literature review found another 30 pediatric cases with sitosterolemia due to ABCG5 gene mutation. The lipid profile was normalized and xanthomas got smaller with combined therapy of a combined low-cholesterol and low-phytosterols diet. LESSONS: These suggested that in patients (especially Asian patients) with multiple xanthomas, severe hypercholesterolemia, or elevated low-density lipoprotein-cholesterol, sitosterolemia should be considered in the differential diagnosis. Early diagnosis is important, and restriction of both cholesterol and phytosterols diet should suggested for these patients.

Two cases of glutaric aciduria type II: how to differentiate from inflammatory myopathies?

Muscle weakness is a nonspecific finding of myopathy of any etiology that include iatrogenic, toxic, endocrinological, infectious, immunologic, and metabolic disorders. Among the metabolic myopathies glutaric aciduria type II (GAII) is an autosomal recessively inherited rare disorder of fatty acid and amino acid metabolisms. The late onset form is heterogeneous in terms of symptomatology and severity and for the cases that chronic manifestations of lipid storage myopathy are the only clues for the disease, differential diagnosis can be challenging. Here we report two cases of GAII: the first one was 18-year old boy who presented with proximal muscle weakness and in another center, he was diagnosed as polymyositis and treated with immunosuppressive therapies. He admitted to our clinic with ongoing muscle weakness and symptoms that were related to the side effects of immunosuppressive therapies. The second case was also presented with muscle weakness. For both cases, muscle biopsies and urinary organic acid analyses were consistent with the diagnosis of GAII. To differentiate inflammatory myositis from non-inflammatory myopathies; rheumatic symptoms, accompanying complaints of the patient and autoantibody positivity can be helpful. To our knowledge this is the first report to underline the differential diagnosis of inflammatory myopathies from metabolic myopathies.

Mitochondrial dysfunction in human skeletal muscle biopsies of lipid storage disorder.

Mitochondria regulate the balance between lipid metabolism and storage in the skeletal muscle. Altered lipid transport, metabolism and storage influence the bioenergetics, redox status and insulin signalling, contributing to cardiac and neurological diseases. Lipid storage disorders (LSDs) are neurological disorders which entail intramuscular lipid accumulation and impaired mitochondrial bioenergetics in the skeletal muscle causing progressive myopathy with muscle weakness. However, the mitochondrial changes including molecular events associated with impaired lipid storage have not been completely understood in the human skeletal muscle. We carried out morphological and biochemical analysis of mitochondrial function in muscle biopsies of human subjects with LSDs (n = 7), compared to controls (n = 10). Routine histology, enzyme histochemistry and ultrastructural analysis indicated altered muscle cell morphology and mitochondrial structure. Protein profiling of the muscle mitochondria from LSD samples (n = 5) (vs. control, n = 5) by high-throughput mass spectrometric analysis revealed that impaired metabolic processes could contribute to mitochondrial dysfunction and ensuing myopathy in LSDs. We propose that impaired fatty acid and respiratory metabolism along with increased membrane permeability, elevated lipolysis and altered cristae entail mitochondrial dysfunction in LSDs. Some of these mechanisms were unique to LSD apart from others that were common to dystrophic and inflammatory muscle pathologies. Many differentially regulated mitochondrial proteins in LSD are linked with other human diseases, indicating that mitochondrial protection via targeted drugs could be a treatment modality in LSD and related metabolic diseases. Cover Image for this Issue: doi: 10.1111/jnc.14177.

Sitosterolemia: A multifaceted metabolic disorder with important clinical consequences.

Sitosterolemia is a metabolic disorder characterized by increased intestinal absorption and tissue accumulation of phytosterols. Although sitosterolemia is considered a rare disease, its prevalence may be significantly higher than initially thought. Indeed, accumulating evidence suggests that patients with unexplained hematologic abnormalities or premature cardiovascular disease in the absence of classic risk factors may exhibit disordered phytosterol metabolism. In this review, we present a patient with sitosterolemia, describe the pathophysiology and the clinical picture of this disorder, and discuss the clinical value of phytosterol supplementation in patients with primary dyslipidemias.

VLCAD deficiency: Follow-up and outcome of patients diagnosed through newborn screening in Victoria.

Very long chain acyl-CoA dehydrogenase (VLCAD) deficiency is an inherited metabolic disorder of fatty acid oxidation. Treatment practices of the disorder have changed over the past 10-15years since this disorder was included in newborn screening programs and patients were diagnosed pre-symptomatically. A genotype-phenotype correlation has been suggested but the discovery of novel mutations make this knowledge limited. Herein, we describe our experience in treating patients (n=22) diagnosed through newborn screening and mutational confirmation and followed up over a median period of 104months. We report five novel mutations. In 2013 we formalised our treatment protocol, which essentially follows a European consensus paper from 2009 and our own experience. The prescribed low natural fat diet is relaxed for patients who are asymptomatic when reaching age 5years but medium-chain triglyceride oil is recommended before and after physical activity regardless of age. Metabolic stability, growth, development and cardiac function are satisfactory in all patients. There were no episodes of encephalopathy or hypoglycaemia but three patients had episodes of muscle pain with our without rhabdomyolysis. Body composition studies showed a negative association between dietary protein intake and percent body fat. Larger patient cohort and longer follow up time are required for further elucidation of genotype-phenotype correlations and for establishing the role of dietary protein in metabolic stability and long-term healthier body composition in patients with VLCAD deficiency.

Outcomes and genotype-phenotype correlations in 52 individuals with VLCAD deficiency diagnosed by NBS and enrolled in the IBEM-IS database.

Very long chain acyl-CoA dehydrogenase (VLCAD) deficiency can present at various ages from the neonatal period to adulthood, and poses the greatest risk of complications during intercurrent illness or after prolonged fasting. Early diagnosis, treatment, and surveillance can reduce mortality; hence, the disorder is included in the newborn Recommended Uniform Screening Panel (RUSP) in the United States. The Inborn Errors of Metabolism Information System (IBEM-IS) was established in 2007 to collect longitudinal information on individuals with inborn errors of metabolism included in newborn screening (NBS) programs, including VLCAD deficiency. We retrospectively analyzed early outcomes for individuals who were diagnosed with VLCAD deficiency by NBS and describe initial presentations, diagnosis, clinical outcomes and treatment in a cohort of 52 individuals ages 1-18years. Maternal prenatal symptoms were not reported, and most newborns remained asymptomatic. Cardiomyopathy was uncommon in the cohort, diagnosed in 2/52 cases. Elevations in creatine kinase were a common finding, and usually first occurred during the toddler period (1-3years of age). Diagnostic evaluations required several testing modalities, most commonly plasma acylcarnitine profiles and molecular testing. Functional testing, including fibroblast acylcarnitine profiling and white blood cell or fibroblast enzyme assay, is a useful diagnostic adjunct if uncharacterized mutations are identified.

Altered Energetics of Exercise Explain Risk of Rhabdomyolysis in Very Long-Chain Acyl-CoA Dehydrogenase Deficiency.

Rhabdomyolysis is common in very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and other metabolic myopathies, but its pathogenic basis is poorly understood. Here, we show that prolonged bicycling exercise against a standardized moderate workload in VLCADD patients is associated with threefold bigger changes in phosphocreatine (PCr) and inorganic phosphate (Pi) concentrations in quadriceps muscle and twofold lower changes in plasma acetyl-carnitine levels than in healthy subjects. This result is consistent with the hypothesis that muscle ATP homeostasis during exercise is compromised in VLCADD. However, the measured rates of PCr and Pi recovery post-exercise showed that the mitochondrial capacity for ATP synthesis in VLCADD muscle was normal. Mathematical modeling of oxidative ATP metabolism in muscle composed of three different fiber types indicated that the observed altered energy balance during submaximal exercise in VLCADD patients may be explained by a slow-to-fast shift in quadriceps fiber-type composition corresponding to 30% of the slow-twitch fiber-type pool in healthy quadriceps muscle. This study demonstrates for the first time that quadriceps energy balance during exercise in VLCADD patients is altered but not because of failing mitochondrial function. Our findings provide new clues to understanding the risk of rhabdomyolysis following exercise in human VLCADD.

Xyloketal B attenuates atherosclerotic plaque formation and endothelial dysfunction in apolipoprotein e deficient mice.

Our previous studies demonstrated that xyloketal B, a novel marine compound with a unique chemical structure, has strong antioxidant actions and can protect against endothelial injury in different cell types cultured in vitro and model organisms in vivo. The oxidative endothelial dysfunction and decrease in nitric oxide (NO) bioavailability are critical for the development of atherosclerotic lesion. We thus examined whether xyloketal B had an influence on the atherosclerotic plaque area in apolipoprotein E-deficient (apoE-/-) mice fed a high-fat diet and investigated the underlying mechanisms. We found in our present study that the administration of xyloketal B dose-dependently decreased the atherosclerotic plaque area both in the aortic sinus and throughout the aorta in apoE-/- mice fed a high-fat diet. In addition, xyloketal B markedly reduced the levels of vascular oxidative stress, as well as improving the impaired endothelium integrity and NO-dependent aortic vasorelaxation in atherosclerotic mice. Moreover, xyloketal B significantly changed the phosphorylation levels of endothelial nitric oxide synthase (eNOS) and Akt without altering the expression of total eNOS and Akt in cultured human umbilical vein endothelial cells (HUVECs). Here, it increased eNOS phosphorylation at the positive regulatory site of Ser-1177, while inhibiting phosphorylation at the negative regulatory site of Thr-495. Taken together, these findings indicate that xyloketal B has dramatic anti-atherosclerotic effects in vivo, which is partly due to its antioxidant features and/or improvement of endothelial function.

Fatty acid oxidation flux predicts the clinical severity of VLCAD deficiency.

PURPOSE: Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD) is an inherited disorder of mitochondrial long-chain fatty acid ß-oxidation (LC-FAO) and is included in many newborn screening (NBS) programs worldwide. Patients may present with hypoketotic hypoglycemia, cardiomyopathy, and/or myopathy, but clinical severity varies widely and the clinical outcome is unpredictable. We investigated predictive markers that may determine clinical severity. METHODS: We developed a clinical severity score (CSS), which was determined for 13 Dutch patients with VLCADD, all of whom were diagnosed before the introduction of VLCADD in NBS to prevent bias from early diagnosis. In cultured skin fibroblasts from these patients, we measured LC-FAO flux (the rate of oleate oxidation), VLCAD activity, and acylcarnitine profiles following palmitate loading. RESULTS: The strongest correlation (r = 0.93; P < 0.0001) was observed between LC-FAO flux and the CSS. VLCAD activity measurement and the C14/C16-to-acylcarnitine ratio correlated much less. A median LC-FAO flux of 6% of control values (range 5.6-6.8%) was associated with cardiomyopathy (P < 0.01), and 32.4% (range 5.6-50.5%) was associated with myopathy (P < 0.05). CONCLUSION: Our results demonstrate a very strong correlation between LC-FAO flux in fibroblasts and the clinical severity of VLCADD. LC-FAO flux measurements may thus predict whether patients are likely to develop symptoms.

Multiple symmetric lipomatosis: a rare disease and its possible links to brown adipose tissue.

AIM: Aim of this study is an updated review of our case series (72 patients) as well as available literature on the Multiple Symmetric Lipomatosis (MSL), a rare disease primarily involving adipose tissue, characterized by the presence of not encapsulated fat masses, symmetrically disposed at characteristic body sites (neck, trunk, proximal parts of upper and lower limbs). DATA SYNTHESIS: The disease is more frequent in males, associated to an elevated chronic alcohol consumption, mainly in form of red wine. Familiarity has been reported and MSL is considered an autosomic dominant inherited disease. MSL is associated to severe clinical complications, represented by occupation of the mediastinum by lipomatous tissue with a mediastinal syndrome and by the presence of a somatic and autonomic neuropathies. Hyper-alphalipoproteinemia with an increased adipose tissue lipoprotein-lipase activity, a defect of adrenergic stimulated lipolysis and a reduction of mitochondrial enzymes have been described. The localization of lipomatous masses suggests that MSL lipomas could originate from brown adipose tissue (BAT). Moreover, studies on cultured pre-adipocytes demonstrate that these cells synthetize the mitochondrial inner membrane protein UCP-1, the selective marker of BAT. Surgical removal of lipomatous tissue is to date the only validated therapeutic approach. CONCLUSIONS: MSL is supposed to be the result of a disorder of the proliferation and differentiation of human BAT cells.

Successful management of pregnancy with very-long-chain acyl-coenzyme A dehydrogenase deficiency.

Very-long-chain acyl-coenzyme A dehydrogenase deficiency (VLCADD) is a rare and life-threatening disease characterized by an enzymatic defect in the fatty acid ß-oxidation pathway. A nulliparous woman with VLCADD showed improvements in serum levels of the long-chain acylcarnitine moiety (C14:1) during pregnancy and successfully delivered a healthy infant vaginally. Pregnancy and vaginal delivery can be successfully completed in patients with VLCADD with careful management.

Food withdrawal lowers energy expenditure and induces inactivity in long-chain fatty acid oxidation-deficient mouse models.

Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is an inherited disorder of mitochondrial long-chain fatty acid ß-oxidation (FAO). Patients with VLCAD deficiency may present with hypoglycemia, hepatomegaly, cardiomyopathy, and myopathy. Although several mouse models have been developed to aid in the study of the pathogenesis of long-chain FAO defects, the muscular phenotype is underexposed. To address the muscular phenotype, we used a newly developed mouse model on a mixed genetic background with a more severe defect in FAO (LCAD(-/-); VLCAD(+/-)) in addition to a validated mouse model (LCAD(-/-); VLCAD(+/+)) and compared them with wild-type (WT) mice. We found that both mouse models show a 20% reduction in energy expenditure (EE) and a 3-fold decrease in locomotor activity in the unfed state. In addition, we found a 1.7°C drop in body temperature in unfed LCAD(-/-); VLCAD(+/+) mice compared with WT body temperature. We conclude that food withdrawal-induced inactivity, hypothermia, and reduction in EE are novel phenotypes associated with FAO deficiency in mice. Unexpectedly, inactivity was not explained by rhabdomyolysis, but rather reflected the overall reduced capacity of these mice to generate heat. We suggest that mice are partly protected against the negative consequence of an FAO defect.-Diekman, E. F., van Weeghel, M., Wanders, R. J. A., Visser, G., Houten, S. M. Food withdrawal lowers energy expenditure and induces inactivity in long-chain fatty acid oxidation-deficient mouse models.

Development and pathomechanisms of cardiomyopathy in very long-chain acyl-CoA dehydrogenase deficient (VLCAD(-/-)) mice.

Hypertrophic cardiomyopathy is a typical manifestation of very long-chain acyl-CoA dehydrogenase deficiency (VLCADD), the most common long-chain ß-oxidation defects in humans; however in some patients cardiac function is fully compensated. Cardiomyopathy may also be reversed by supplementation of medium-chain triglycerides (MCT). We here characterize cardiac function of VLCAD-deficient (VLCAD(-/-)) mice over one year. Furthermore, we investigate the long-term effect of a continuous MCT diet on the cardiac phenotype. We assessed cardiac morphology and function in VLCAD(-/-) mice by in vivo MRI. Cardiac energetics were measured by (31)P-MRS and myocardial glucose uptake was quantified by positron-emission-tomography (PET). Metabolic adaptations were identified by the expression of genes regulating glucose and lipid metabolism using real-time-PCR. VLCAD(-/-) mice showed a progressive decrease in heart function over 12 months accompanied by a reduced phosphocreatine-to-ATP-ratio indicative of chronic energy deficiency. Long-term MCT supplementation aggravated the cardiac phenotype into dilated cardiomyopathy with features similar to diabetic heart disease. Cardiac energy production and function in mice with a ß-oxidation defect cannot be maintained with age. Compensatory mechanisms are insufficient to preserve the cardiac energy state over time. However, energy deficiency by impaired ß-oxidation and long-term MCT induce cardiomyopathy by different mechanisms. Cardiac MRI and MRS may be excellent tools to assess minor changes in cardiac function and energetics in patients with ß-oxidation defects for preventive therapy.