Rapid haemoglobin A and S quantification using Tosoh HLC-723G8 in variant mode for patients with sickle cell disease.

The management of life-threatening complications in patients with sickle cell disease (SCD) requires an accurate and reproducible quantification of haemoglobin A (HbA) and S (HbS) with a short turnaround time and 24-7 availability. We propose a novel method for quantifying HbA and HbS using the glycated haemoglobin (HbA1c) assay on a Tosoh HLC-723G8 (G8) analyser in variant mode. HbA and HbS results obtained using our method highly correlated with results obtained using a reference method (r > 0.99 for 124 samples of patients with SCD or sickle cell trait). Our method met laboratory requirements for linearity (coefficient of variation [CV] and bias <5%), between-run and within-run reproducibility (CV <10%) and carryover (<0.5%) over the range of HbS and HbA values expected in a therapeutic context. Using the G8 analyser in variant mode is viable for monitoring HbA and HbS concentrations in dire situations. This method is easy to use, quick (1.6 min per sample), and automatable and produces highly reproducible results without significant bias. Finally, it does not require modifications to the analytical pipeline recommended by the supplier, enabling a 24-7 availability without disrupting routine monitoring of HbA1c in the laboratory.

Case report: Diagnosis of ADCY5-related dyskinesia explaining the entire phenotype in a patient with atypical citrullinemia type I.

In this case study, we report the case of a 13-year-old girl with citrullinemia type 1 (MIM #215700), an autosomal recessive inherited disorder of the urea cycle, which was confirmed by the identification of a homozygous pathogenic variant in the argininosuccinate synthetase 1 (ASS1) gene. However, the patient presented abnormal hyperkinetic movements with global developmental delay and clinical signs that were not fully consistent with those of citrullinemia type 1 or with those of her siblings with isolated citrullinemia type 1. Exome sequencing showed the presence of a de novo heterozygous pathogenic variant in the adenylate cyclase type 5 (ADCY5) gene. The variant confirmed the overlap with the so-called ADCY5-related dyskinesia with orofacial involvement, which is autosomal dominant (MIM #606703), a disorder disrupting the enzymatic conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). In addition to the citrullinemia-related low-protein diet and arginine supplementation, the identification of this second disease led to the introduction of a treatment with caffeine, which considerably improved the dyskinesia neurological picture. In conclusion, this case highlights the importance of clinical-biological confrontation for the interpretation of genetic variants, as one hereditary metabolic disease may hide another with therapeutic consequences. Summary: This article reports the misleading superposition of two inherited metabolic diseases, showing the importance of clinical-biological confrontation in the interpretation of genetic variants.

Late-onset argininosuccinic aciduria in a 72-year-old man presenting with fatal hyperammonemia.

Argininosuccinate lyase deficiency (ASLD, MIM #207900) is an inherited urea cycle disorder. There are mainly two clinical forms, an acute neonatal form which manifests as life-threatening hyperammonemia, and a late-onset form characterised by polymorphic neuro-cognitive or psychiatric presentation with transient hyperammonemia episodes. Here, we report a late-onset case of ASLD in a 72-year-old man carrying a homozygous pathogenic variant in the exon 16 of the ASL gene, presenting for the first time with fatal hyperammonemic coma. This case report shows the need to systematically carry out an ammonia assay when faced with an unexplained coma.

Ketogenic Diet Impairment of Mycobacterium ulcerans Growth and Toxin Production and Enhancement of Host Response to Infection in an Experimental Mouse Model.

Ketogenic diets have been used to treat diverse conditions, and there is growing evidence of their benefits for tissue repair and in inflammatory disease treatment. However, their role in infectious diseases has been little studied. Buruli ulcer (Mycobacterium ulcerans infection) is a chronic infectious disease characterized by large skin ulcerations caused by mycolactone, the major virulence factor of the bacillus. In the current study, we investigated the impact of ketogenic diet on this cutaneous disease in an experimental mouse model. This diet prevented ulceration, by modulating bacterial growth and host inflammatory response. ß-hydroxybutyrate, the major ketone body produced during ketogenic diet and diffusing in tissues, impeded M. ulcerans growth and mycolactone production in vitro underlying its potential key role in infection. These results pave the way for the development of new patient management strategies involving shorter courses of treatment and improving wound healing, in line with the major objectives of the World Health Organization.

Epidemiological and clinical factors associated with post-exertional malaise severity in patients with myalgic encephalomyelitis/chronic fatigue syndrome.

BACKGROUND: Post-exertional malaise (PEM), the cardinal feature of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), occurs generally after exposure to a stressor. It is characterized by the worsening of ME/CFS symptoms and results in aggravating the course of the disease and the quality of life of patients. Due to its unpredictable onset, severity, and recovery time, identifying patients with higher risk for severe PEM would allow preventing or reducing its occurrence. We thus aimed at defining possible factors that could be associated with PEM severity. METHODS: Adult patients fulfilling ME international consensus criteria who attended the internal medicine department of University hospital Angers-France between October 2011 and December 2019 were included retrospectively. All patients were systematically hospitalized for an etiological workup and overall assessment. We reviewed their medical records for data related to the assessment: epidemiological data, fatigue features, clinical manifestations, and ME/CFS precipitants. PEM severity was appreciated by the Center for Disease Control self-reported questionnaire. The study population was classified into quartiles according to PEM severity scores. Analyses were performed with ordinal logistic regression to compare quartile groups. RESULTS: 197 patients were included. PEM severity was found to be positively associated with age at disease onset ≥ 32 years (OR 1.8 [95% CI 1.1-3.0] (p = 0.03)), recurrent infections during the course of the disease (OR 2.1 [95% CI 1.2-3.7] (p = 0.009)), and when ME/CFS was elicited by a gastrointestinal infectious precipitant (OR 5.7 [1.7-19.3] (p = 0.006)). CONCLUSION: We identified some epidemiological and clinical features, which were positively associated with PEM severity in subsets of ME/CFS patients. This could help improving disease management and patients' quality of life.

Sickle Cell Disease: Metabolomic Profiles of Vaso-Occlusive Crisis in Plasma and Erythrocytes.

The metabolomic profile of vaso-occlusive crisis, compared to the basal state of sickle cell disease, has never been reported to our knowledge. Using a standardized targeted metabolomic approach, performed on plasma and erythrocyte fractions, we compared these two states of the disease in the same group of 40 patients. Among the 188 metabolites analyzed, 153 were accurately measured in plasma and 143 in red blood cells. Supervised paired partial least squares discriminant analysis (pPLS-DA) showed good predictive performance for test sets with median area under the receiver operating characteristic (AUROC) curves of 99% and mean p-values of 0.0005 and 0.0002 in plasma and erythrocytes, respectively. A total of 63 metabolites allowed discrimination between the two groups in the plasma, whereas 61 allowed discrimination in the erythrocytes. Overall, this signature points to altered arginine and nitric oxide metabolism, pain pathophysiology, hypoxia and energetic crisis, and membrane remodeling of red blood cells. It also revealed the alteration of metabolite concentrations that had not been previously associated with sickle cell disease. Our results demonstrate that the vaso-occlusive crisis has a specific metabolomic signature, distinct from that observed at steady state, which may be potentially helpful for finding predictive biomarkers for this acute life-threatening episode.

[Multiparametric biochemical analysis revealing an increase of homocysteinemia and NT-proBNP in hypertensive patients living in Bamako (Mali)]. / Analyse biochimique multi-paramétrique révélant une augmentation de l'homocystéinémie et du NT-ProBNP chez les patients hypertendus à Bamako (Mali).

INTRODUCTION: Arterial hypertension is a major public health problem in sub-Saharan Africa due to its high frequency and to the cardiovascular risk that it entails. The purpose of this study was to assess the prevalence of clinical and biological risk factors of hypertension in Bamako (Mali). METHODS: We conducted a case-control study, stratified in function of the sex, of 72 participants including 36 patients with hypertension and 36 controls. Twenty-two plasma biochemical parameters have been measured and analyzed using univariate and multivariate tests. RESULTS: Hyperhomocysteinemia was found in 55.6% of women (p = 0.03) and 100% of men (p = 0.007) with hypertension. High NT-proBNP was also found in 16.7% of women (VIP > 1 in multivariate model) and of men with hypertension (p = 0.00006). A good multivariate predictive model (OPLS-DA) was only obtained in women with high blood pressure, with Q2cum = 0.73, attesting severe sexual dimorphism associated with arterial hypertension. This model involved eight parameters whose plasma concentration was modified (homocysteine, NT-proBNP, potassium, urea, blood glucose, sodium, chlorine and total proteins). CONCLUSION: We registered a significant association between hyperhomocysteinemia and arterial hypertension. Therefore, the assay of homocysteine associated with good management would decrease the risk of cardiovascular diseases while improving the quality of life of hypertensive patients.

Effects of sildenafil on maximum walking time in patients with arterial claudication: The ARTERIOFIL study.

BACKGROUND: Patients with lower extremity peripheral artery disease (PAD) frequently experience claudication, a clinical symptom indicative of reduced walking capacity. Recommended care consists of exercise rehabilitation combined with optimal medical treatment and surgery. The effects of a single oral dose of sildenafil, a phosphodiesterase type-5 inhibitor, on patients with claudication are discussed. The aim of this study was to test the efficacy of a single 100 mg dose of sildenafil compared to placebo in terms of maximal walking time (MWT) in patients with claudication. METHODS: The ARTERIOFIL study is a crossover, double-blind, prospective, randomized, single-center study conducted at Angers University Hospital in France. MWT (primary endpoint) was assessed using a treadmill test (10% incline; 3.2 km/h). Secondary endpoints (pain-free walking time (PFWT), transcutaneous oximetry during exercise and redox cycle parameters and safety) were also studied. RESULTS: Fourteen patients were included of whom two were ultimately excluded. In the 12 remaining patients, the MWT was significantly improved during the sildenafil period compared with the placebo period (300 s [95% CI 172 s-428 s] vs 402 s [95% CI 274 s-529 s] p < 0.01). Sildenafil had no significant effect on pain-free walking time or skin tissue oxygenation during exercise. According to redox cycle parameters, sildenafil significantly reduced blood glucose and pyruvate levels and the 3-hydroxybutyrate/acetoacetate ratio, while there was no significant effect on lactate, 3-hydroxybutyrate, acetoacetate and free fatty acid levels. Symptomatic transient hypotension was observed in two women. CONCLUSIONS: The ARTERIOFIL study has shown that a single 100 mg oral dose of sildenafil had a significant effect on increase in MWT but had no significant effects on PFWT and oxygenation parameters in patients with claudication. A double-blind, prospective, randomized, multicenter study (VIRTUOSE©) is ongoing to evaluate the chronic effect of six month-long sildenafil treatment on MWT in PAD patients with claudication. CLINICAL TRIAL REGISTRATION: This clinical trial was registered at clinicaltrials.gov, registration. number: NCT02832570, (https://clinicaltrials.gov/ct2/show/NCT02832570).

Alagille syndrome: a case report.

We report the case of an infant hospitalized for neonatal anoxic ischemia in whom the diagnosis of Alagille syndrome (SAG ; MIM # 118450) was suspected in the presence of major cholestasis, cardiac malformations, suggestive facial dysmorphia, and vertebral and ocular abnormalities. This diagnosis was later confirmed by the detection of a heterozygous pathogenic variant in the gene JAG1, i.e. the gene predominantly responsible for this syndrome with autosomal dominant transmission, which affects about 1 in 30 000 births. The purpose of this presentation is to highlight this relatively unknown syndrome, both from the diagnostic and physiopathological points of view. This clinical case is also an opportunity to discuss pseudo-bisalbuminemia, accidentally discovered in the patient during the exploration of serum proteins by capillary electrophoresis. In total, the medical biologist is directly concerned by the multidisciplinary management of this syndrome, which involves biological perturbances in multiple organs.

A Plasma Metabolomic Signature Involving Purine Metabolism in Human Optic Atrophy 1 (OPA1)-Related Disorders.

Purpose: Dominant optic atrophy (DOA; MIM [Mendelian Inheritance in Man] 165500), resulting in retinal ganglion cell degeneration, is mainly caused by mutations in the optic atrophy 1 (OPA1) gene, which encodes a dynamin guanosine triphosphate (GTP)ase involved in mitochondrial membrane processing. This work aimed at determining whether plasma from OPA1 pathogenic variant carriers displays a specific metabolic signature. Methods: We applied a nontargeted clinical metabolomics pipeline based on ultra-high-pressure liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) allowing the exploration of 500 polar metabolites in plasma. We compared the plasma metabolic profiles of 25 patients with various OPA1 pathogenic variants and phenotypes to those of 20 healthy controls. Statistical analyses were performed using univariate and multivariate (principal component analysis [PCA], orthogonal partial least-squares discriminant analysis [OPLS-DA]) methods and a machine learning approach, the Biosigner algorithm. Results: A robust and relevant predictive model characterizing OPA1 individuals was obtained, based on a complex panel of metabolites with altered concentrations. An impairment of the purine metabolism, including significant differences in xanthine, hypoxanthine, and inosine concentrations, was at the foreground of this signature. In addition, the signature was characterized by differences in urocanate, choline, phosphocholine, glycerate, 1-oleoyl-rac-glycerol, rac-glycerol-1-myristate, aspartate, glutamate, and cystine concentrations. Conclusions: This first metabolic signature reported in the plasma of patient carrying OPA1 pathogenic variants highlights the unexpected involvement of purine metabolism in the pathophysiology of DOA.

Myoadenylate deaminase deficiency: a frequent cause of muscle pain A case detected by exercise testing.

Myoadenylate deaminase deficit (MAD, MIM#615511) is the most common cause of metabolic myopathies with an estimated prevalence of 1-2% in the general population. We report the case of a 39-year-old man suffering from severe skeletal muscle pain that had developed gradually for 4 years. A moderate increase in creatine kinase (CK) was the only biological sign observed. This study takes a closer look at a common but poorly known pathology and highlights the interest of the dynamic metabolic investigations carried out during exercise stress test with a cycle ergometer. Our non-invasive clinical and biological examination, at the interface between physiology and biology, disclosed the total absence of a physiological increase in plasma ammonia evocative of MAD. However, MAD was later confirmed by histochemistry and molecular studies, which revealed the presence of the recurrent homozygous pathogenic variant affecting the adenosine monophosphate deaminase 1 gene (AMPD1) in most patients with MAD.

Neurotoxicity of Insecticides.

BACKGROUND: Human exposure to insecticides raises serious public health concerns worldwide. Insecticides constitute a wide-ranging heterogeneous group of chemicals, most of which target the nervous system and disrupt neurometabolism and/or neurotransmission. Although the acute effects of insecticide poisoning in humans are well documented, the chronic and long-term effects remain difficult to investigate. OBJECTIVES AND METHOD: We sought to review the present state-of-knowledge of acute, chronic, neurodevelopmental and neurological consequences of human exposure to insecticides. RESULTS: Animal and epidemiologic studies indicate cognitive, behavioral and psychomotor alterations in mammals chronically exposed to insecticides. Parkinson's and Alzheimer's diseases, amyotrophic lateral sclerosis, and depression, have been regularly associated with insecticide exposure. Clinical studies, supported by experiments on animal models, demonstrate the neurotoxic impact of insecticide exposure during the period of cerebral development, the developing brain being particularly vulnerable to the action of insecticides. Moreover, detoxifying systems that are highly polymorph lead to great inter-individual variability in susceptibility to the neurotoxic effects of insecticides. CONCLUSION: Studies on mild chronic exposure to insecticides suggest significant involvement in the pathogenesis of multifactorial neurological diseases. However, the tardive appearance of neurodegenerative disorders and the large variability of inter-individual susceptibility to neurotoxicants make it difficult to assess the relative contribution of insecticide exposure. Close vigilance should therefore be exercised with regard to possible exposure to insecticides, particularly during the period of cerebral development.

Pituitary stalk interruption syndrome: a rare and severe cause of pituitary deficiency Laboratory diagnosis of a newborn case.

We report the case of a newborn with neonatal hypotonia associated to a micropenis and a bilateral cryptorchidia. The discovery of severe hypoglycemia at 0.22 mmol/L led to further biological investigations that revealed sharply decreased levels of several hypophyseal hormones. Altered corticotropic, somatotropic, thyreotropic, and gonadotropic axes finally suggested congenital hypophyseal insufficiency. This diagnostic was confirmed by a brain MRI (magnectic resonance imaging), which revealed a total interruption of the pituitary stalk. Immediate substitutive hormonal treatment allowed a clinical improvement of the condition and limited the risk of further episodes of hypoglycemia. The pituitary stalk interruption syndrome (PSIS), a very rare congenital disorder, has an estimated incidence of about 1:200.000. This developmental anomaly of the hypophysis calls for urgent diagnosis since prognosis depends on the rapid implementation of substitutive hormonal therapy. The hormonal deficit in the newborn affected by PSIS is often of a multiple nature with a constant somatotropic deficit, thus requiring the exploration of the different antehypophyseal axes. Despite the fact that PSIS is a rare disorder, it should always be kept in the differential diagnosis of newborn presenting with hypoglycemia. Since the interpretation of hormonal assays is particularly delicate at birth, close clinico-biological cooperation is essential for rapid diagnosis of PSIS and appropriate adaptation of the short- and long-term therapeutic management of the newborn.

Type I hyperlipidaemia caused by lipoprotein lipase deficiency in a nurseling: the role of the clinical laboratory in processing biological samples and contributing to the diagnosis and therapeutic follow-up of patients.

We describe the case of a two-months-old nurseling admitted to the paediatric emergency unit for vomiting. Upon clinical examination, the paediatrician found the child pale with an alteration of the general condition, a tachycardia and severe hepatomegaly. Blood sampling revealed hyperlipasemia at 228 IU/L and lactescent plasma, prompting the biologist to complete the prescription by lipid profile analysis. Severe hypertriglyceridaemia peaking at 47 mmol/L was then identified. The hypothesis of acute pancreatitis due to familial chylomicronaemia was proposed. The diagnosis of type I hyperlipidaemia due to complete lipoprotein lipase deficiency was later confirmed by the molecular genetic identification of a homozygous mutation in the LPL gene encoding the enzyme. This disease is extremely rare, and occurrence of first clinical symptoms before one year of age is possible although exceptional. The treatment, including digestive rest and parenteral nutrition, allowed rapid improvement of the acute episode and long-term dietary management prevented recurrent acute pancreatitis. In addition to the importance of clinical and laboratory cooperation, this case report provides an opportunity for discussing the analytical interferences and pre-analytical procedures involved in the exploration of biological parameters in hyperlipaemic plasma.

Mitochondrial energetic defects in muscle and brain of a Hmbs-/- mouse model of acute intermittent porphyria.

Acute intermittent porphyria (AIP), an autosomal dominant metabolic disease (MIM #176000), is due to a deficiency of hydroxymethylbilane synthase (HMBS), which catalyzes the third step of the heme biosynthetic pathway. The clinical expression of the disease is mainly neurological, involving the autonomous, central and peripheral nervous systems. We explored mitochondrial oxidative phosphorylation (OXPHOS) in the brain and skeletal muscle of the Hmbs(-/-) mouse model first in the basal state (BS), and then after induction of the disease with phenobarbital and treatment with heme arginate (HA). The modification of the respiratory parameters, determined in mice in the BS, reflected a spontaneous metabolic energetic adaptation to HMBS deficiency. Phenobarbital induced a sharp alteration of the oxidative metabolism with a significant decrease of ATP production in skeletal muscle that was restored by treatment with HA. This OXPHOS defect was due to deficiencies in complexes I and II in the skeletal muscle whereas all four respiratory chain complexes were affected in the brain. To date, the pathogenesis of AIP has been mainly attributed to the neurotoxicity of aminolevulinic acid and heme deficiency. Our results show that mitochondrial energetic failure also plays an important role in the expression of the disease.

[Multiorgan failure after sickle cell vaso occlusive attack: integrated clinical and biological emergency]. / Complications en cascade avec défaillance multiviscérale au cours d'une drépanocytose : gestion coordonnée de l'urgence au laboratoire et au service de réanimation médicale.

We describe the case of a 30-year-old patient, suffering from composite S/ß + sickle cell disease. He was hospitalized following a vaso-occlusive attack with acute bone pains. Despite an analgesic treatment and transfusion of three units of red blood cells, a non-regenerative anemia appeared within 24 hours. One day later an acute chest syndrome with atelectasis of the left lung and desaturation and multi-organ failure occurred and necessitated the patient's intubation and required him to be placed in an artificial coma. A bronchoalveolar lavage was performed, which eliminated pneumonia but proved, after staining with oil red O, many neutral fatty acid microvacuoles in more than 80% of macrophages, suggesting a pulmonary fat embolism. The hypothesis of a bone marrow necrosis causing a pulmonary fat embolism was discussed and confirmed the next day by the characteristic appearance of the bone marrow. A therapeutic protocol associating iteratively bleeding and red blood cells transfusion was administered on the second day with the objective of maintaining haemoglobin S at less than 20% rate. Successive haemoglobin S assay was applied using a high performance liquid chromatography (HPLC) technique with a quick response within one hour after transfusion or bleeding. This protocol resulted in an improvement in the patient's condition, with a gradual normalization of vital signs and extubation twelve days later and discharge without sequelae twenty-five days later. The succession of rare but serious sickle cell complications anaemia which occurred in this patient could be controlled by adapting the laboratory for the clinical emergency.

Pro-oxidant effect of ALA is implicated in mitochondrial dysfunction of HepG2 cells.

Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using the MnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300 µM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300 µM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria.

Acute intermittent porphyria causes hepatic mitochondrial energetic failure in a mouse model.

Acute intermittent porphyria (AIP), an inherited hepatic disorder, is due to a defect of hydroxymethylbilane synthase (HMBS), an enzyme involved in heme biosynthesis. AIP is characterized by recurrent, life-threatening attacks at least partly due to the increased hepatic production of 5-aminolaevulinic acid (ALA). Both the mitochondrial enzyme, ALA synthase (ALAS) 1, involved in the first step of heme biosynthesis, which is closely linked to mitochondrial bioenergetic pathways, and the promise of an ALAS1 siRNA hepatic therapy in humans, led us to investigate hepatic energetic metabolism in Hmbs KO mice treated with phenobarbital. The mitochondrial respiratory chain (RC) and the tricarboxylic acid (TCA) cycle were explored in the Hmbs(-/-) mouse model. RC and TCA cycle were significantly affected in comparison to controls in mice treated with phenobarbital with decreased activities of RC complexes I (-52%, (**)p<0.01), II (-50%, (**)p<0.01) and III (-55%, (*)p<0.05), and decreased activity of α-ketoglutarate dehydrogenase (-64%, (*)p<0.05), citrate synthase (-48%, (**)p<0.01) and succinate dehydrogenase (-53%, (*)p<0.05). Complex II-driven succinate respiration was also significantly affected. Most of these metabolic alterations were at least partially restored after the phenobarbital arrest and heme arginate administration. These results suggest a cataplerosis of the TCA cycle induced by phenobarbital, caused by the massive withdrawal of succinyl-CoA by ALAS induction, such that the TCA cycle is unable to supply the reduced cofactors to the RC. This profound and reversible impact of AIP on mitochondrial energetic metabolism offers new insights into the beneficial effect of heme, glucose and ALAS1 siRNA treatments by limiting the cataplerosis of TCA cycle.

Adenine nucleotide translocase is involved in a mitochondrial coupling defect in MFN2-related Charcot-Marie-Tooth type 2A disease.

Charcot-Marie-Tooth type 2A disease (CMT2A), a dominantly inherited peripheral neuropathy, is caused by mutations in MFN2, a mitochondrial fusion protein. Having previously demonstrated a mitochondrial coupling defect in CMT2A patients' fibroblasts, we here investigate mitochondrial oxygen consumption and the expression of adenine nucleotide translocase (ANT) and uncoupling proteins from eight other patients with the disease. The mitochondrial uncoupling was associated with a higher respiratory rate, essentially involving complex II proteins. Furthermore, a twofold increase in the expression of ANT led to the reduced efficiency of oxidative phosphorylation in CMT2A cells, suggesting that MFN2 plays a role in controlling ATP/ADP exchanges.