A case of mitochondrial episodic myopathy (variant without optic atrophy and reversible leukoencephalopathy) in the Carpathian region

Mitochondrial episodic myopathy with/or without optic nerve atrophy and reversible leukoencephalopathy (MEOAL, OMIM 251900) belongs to rare primary mitochondrial myopathies, caused by nuclear genome DNA mutations with autosomal recessive inheritance. Purpose - to inform about the case of this current rare mitochondrial miopathy and encrease the knowledge of practical doctors in scope of diagnostics and treatment of the current orphan pathology Clinical case. In the clinical case being presented herein, the sick child had a severe course of the disease in the form of episodes of severe myopathy (during one of them there was a need for long-term mechanical lungventilation with the placement of a tracheostomy) in combination with severe metabolic crises. During crises, persistent keto- and lactic acidosis, a sharp increase in transaminases (alanine aminotransferase and aspartate aminotransferase) and creatine kinase in blood serum were observed. The patient did not have optic nerve atrophy or leukoencephalopathy. A similar course of the disease is described in the literature by different authors in only 3 cases. Molecular genetic analysis (Invitae laboratory, San Francisco) revealed 2 mutations of the FDX2 gene (the disease is associated with this gene) with uncertain pathogenic significance. Considering the presence of cardinal symptoms of MEOAL, this diagnosis was set to the patient, and therefore the detected mutations of the FDX2 gene should be considered as pathogenic. Conclusions. A thorough syndromic analysis of the phenotype together with a set of paraclinical examinations, including modern molecular genetic methods, made it possible to establish a clinical diagnosis of an extremely rare primary mitochondrial myopathy, which will contribute to further elucidation of relationships in the «genotype-phenotype» system and, possibly, reclassification of pathogenic genotypes in modern databases, as well as finding optimal approaches in treatment and rehabilitation of patients. The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.