Résumé :
|
Communication n° 679 INTRODUCTION ETF-QO deficiency is a rare cause of myopathy. Three forms have been described : two forms with a neonatal onset (type I,II), and a late onset form (III). Very few late onset cases have been published in adulthood. Symptoms included myopathy with metabolic disorders: hypoglycemia, acidosis, and hyperammonemia, released by fasting. Symptoms have been reported to be riboflavin responsive. We report here a new late onset case. METHODS CASE REPORT A 36 year-old woman complained of proximal muscle weakness with muscle pain for ten months. First clinical examination revealed mild proximal muscle weakness and decreased tendon reflexes. During the following year, she experienced two episodes of acute worsening weakness, with dyspnea, nausea and dropped head. First episode relapsed incompletely with L-carnitine. Second episode was more severe with marked dysphagia, marked proximal muscle weakness with walking loss, areflexia and dropped head. Episodes were associated with rhabdomyolysis, acidosis, and hypoglycemia only during the second episode. Symptoms improved drammaticaly by avoiding fasting, and with L-carnitine and riboflavin supplementation. No relapses occurred during the following year after treatment. RESULTS Two muscle biopsies showed an increased lipid content, numerous ragged-red fibres in the first biopsy. Mitochondrial oxidative metabolism analysis revealed decreased complex I,II and II+III activity in the first biopsy and only a decreased complex I activity in the second one. Free muscle carnitine level was low with normal total carnitine. Plasmatic acylcarnitines profile revealed increased long chain acylcarnitines, whereas C5,C8,C10 acylcarnitines were low. Urine chromatographic analysis demonstrated organic acids and acylglycins increase. All these abnormalities were consistent with MADD. ETF enzymatic activity muscle study pointed out ETF-QO deficiency. CONCLUSION In adulthood, ETF-QO deficiency can provoke a myopathy with dropped head. When such features are associated with a lipidic myopathy, a chromatographic organic acids urine analysis and a plasmatic acylcarnitine profil could be performed in order to detect a MADD. Riboflavin supplementation can dramatically improve patients in such cases.
|