Myopathie nécrosante auto-immune associée aux anticorps anti-hydroxy-méthyl-glutaryl-coenzyme A réductase

Introduction

Statins or 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase inhibitors (HMGCR) are among the most commonly prescribed treatment in France. They may be responsible for muscular intolerance with variable severity. They have been recently involved in the occurrence of an acquired inflammatory myopathy associated with anti-HMGCR antibodies. This new type of toxic myopathy remains poorly known by clinicians.

Observation

We report a 61-year-old woman treated with a statin for many years who developed a lower and upper limb disabling myopathy with a rapid unfavourable course despite treatment withdrawal. Clinical history and investigations, especially including an assay for anti-HMGCR antibodies led to the diagnosis of autoimmune necrotizing myopathy with anti-HMGCR antibodies. Subsequent initiation of an immunosuppressive treatment by corticosteroids and methotrexate was effective.

Conclusion

Statins may unmask or cause an autoimmune necrotizing myopathy associated with the presence of anti-HMGCR antibodies. Their identification is now routinely available. An immunosuppressive treatment is necessary and justified by the autoimmune nature of the disease.     

Les myopathies nécrosantes acquises

Necrotizing myopathies (MN) are defined by a specific histological pattern. They are characterized by a predominant muscle fibre necrosis and regeneration but with little or no associated inflammation. This histological pattern is observed in acquired myopathy but also in muscular dystrophy. Acquired NM can be secondary to drugs or toxics, and if not, autoimmune mechanisms have to be suspected. Necrotizing autoimmune myopathy is recognized as a subgroup of idiopathic inflammatory myopathies, different from other myositides. Generally, patients present a rapidly progressive and severe symmetrical proximal weakness with high serum creatine kinase level, associated in some patients with cardiac involvement. On the other hand, a slower progression may sometimes be observed, that could lead to erroneous diagnosis of muscular dystrophy. Necrotizing autoimmune myopathy may be associated to specific autoantibodies against signal recognition particle, or more recently described, against 3-hydroxy-3-methylglutaryl-coenzyme A reductase. Necrotizing auto-immune myopathy can also be described in association with connective tissue diseases such as lupus or sclerodermia. In remaining cases, cancer association may be observed. Necrotizing autoimmune myopathies are now considered as a new entity, treatable by immunosuppressants and which should not be misdiagnosed as a muscular dystrophy.     

Diabète et cardiopathie hypokinétique, quand évoquer une cytopathie mitochondriale ?

The association between diabetes mellitus and hypokinetic cardiomyopathy is frequent. We report a case of diabetes and hypokinetic cardiopathy in a 40-year-old man which led to the hypothesis of maternally inherited diabetes and deafness (MIDD) due to a mitochondrial disease. This diagnosis was confirmed by genetic testing which showed a DNA A3243G mutation in the mitochondria, the prevalence of which is 1–2% in diabetes mellitus. Cardiac abnormalities are frequent (18–34% of patients depending on the series) and the co-existence of left ventricular hypertrophy and systolic dysfunction is suggestive of this disease. Some authors have proposed co-enzyme Q as a treatment to improve the left ventricular ejection fraction and insulin secretion.     

Inherited defects of thyroid hormone metabolism

Intracellular metabolism of thyroid hormone and availability of the active hormone, triiodothyronine is regulated by three selenoprotein iodothyronine deiodinases (Ds). While acquired changes in D activities are common, inherited defects in humans have not been identified. Selenium (Se) is an essential trace element required for the biosynthesis of selenoproteins, and selenocysteine insertion sequence (SECIS) binding protein 2 (SBP2) represents a key trans-acting factor for the cotranslational insertion of selenocysteine into selenoproteins. In 2005 we reported the first mutations in the SBP2 gene in two families in which the probands presented with transient growth retardation associated with abnormal thyroid function tests, low triiodothyronine (T₃), high thyroxine (T₄) and reverse T₃, and slightly elevated thyrotropin. Affected children were either homozygous or compound heterozygous for SBP2 gene mutations and the relatively mild phenotype was due to partial SBP2 deficiency, affecting the expression of a subset of selenoproteins. In vivo studies of these subjects have explored the effects of Se and thyroid hormone supplementation. In vitro experiments have provided new insights into the effect of SBP2 mutations. A broader and more complex phenotype was brought to light by the subsequent identification of three new cases from different families with SBP2 gene mutations. These mutations caused a severe SBP2 deficiency resulting in reduced synthesis of most of the 25 known human selenoproteins. Here we summarize the clinical presentation of SBP2 mutations, their effect on SBP2 function and downstream consequences for selenoprotein synthesis and function.     

Déficit multiple en acyl-CoA déshydrogénases : une cause traitable de lipidose musculaire d’origine génétique

Introduction

Multiple acyl-CoA dehydrogenase deficiency (MADD) is a rare genetic disease involving fatty acid oxidation. It is due to the deficiency of one of the two electron transporters: electron transfer flavoprotein (ETF) or electron transfer flavoprotein ubiquinone oxydoreductase (ETF-QO). Symptoms begin more often in childhood or in young adulthood with a multisystemic disease with encephalopathy or muscular weakness.

Case reports

We report here two adult cases with ETF-QO deficiency, confirmed by mutation analysis (ETFDH gene), revealed by a muscular weakness associated with muscle lipidosis. One of our patients presented an acute encephalopathy with vomiting ten years before the onset of muscular symptoms. The second patient exhibited a slowly progressive pelvic girdle muscle weakness. Diagnosis was established by characteristic abnormalities of acylcarnitine profile by tandem mass spectrometry. For both patients, a dramatic clinical improvement was observed under treatment with riboflavine and L-carnitine.

Conclusion

Since it is a treatable disorder, this diagnosis must be considered by performing an acylcarnitine profile in all patients presenting with an unexplained muscular weakness.     

Association myopathie inflammatoire et hépatocarcinome : à propos d’une observation et revue de la littérature

Association inflammatory myopathies and tumors are not fortuitous but association with hepatocellular carcinoma is rarely reported in literature. We described a case of association polymyositis hepatocellular carcinoma in 37-year-old black African patient, with fatal issue.     

Central Core Disease mit „structured cores“ in Typ II-Fasern

Zusammenfassung Es wird über einen sporadischen Fall einer congenitalen langsam progredienten neuromuskulären Erkrankung berichtet. Die im Rahmen der Muskelbiopsie zu erhebenden lichtmikroskopischen, ultrastrukturellen und enzymhistochemischen Befunde entsprechen einer Central Core Disease mit structured cores in Typ II-Fasern.Die Arbeit wurde mit Unterstützung der Friedrich Baur-Stiftung, München, durchgeführt.     

Chloroquin-induzierte Myopathie

Zusammenfassung Die Myotoxizität von Chloroquin und Hydroxychloroquin ist langjährig bekannt. Üblicherweise kann es dosisabhängig in den ersten 24 Monaten der Medikation zur Entwicklung einer Gliedergürtelschwäche im Rahmen einer vakuolären Myopathie kommen. Wir berichten über einen Fall mit Ausbildung einer Muskelschwäche nach siebenjähriger Einnahme von täglich 250 mg Chloroquinphosphat (=155 mg Chloroquinbase). Auch nach langjähriger, scheinbar gut vertragener Chloroquinmedikation muss auf die Ausbildung relevanter Nebenwirkungen geachtet werden.     

Cyclosporin-induced toxic neuromyopathy

INTRODUCTION: Cyclosporine is an immunosuppressive treatment whose side effects limit its usefulness. Among neurological side effects, neuropathies or myopathies have been reported, specially inpatients given combinations of cyclosporine with co-enzyme A reductase inhibitors. CASE REPORT: We report here the case of a 67-year-old woman who developed few months after a kidney graft sensorimotor disorders which progressed rapidly. Since all etiologies of such a disorder were ruled out, the hypothesis of toxicity exclusively induced by cyclosporine was suggested and confirmed by the improvement observed after its withdrawal. CONCLUSION: This observation highlights the fact that cyclosporine may induce neuromyopathies even when given alone at the therapeutic dosage.