A CASE OF ADULT ONSET PURE MITOCHONDRIAL MYOPATHY

Mitochondriopathies (MCPs) are a group of disorders that are caused by an inability in the synthesis of mitochondrial proteins or transfer RNA (tRNA) and ribosomal RNA (rRNAs) encoded by nuclear DNA (nDNA) or mitochondrial DNA (mtDNA) either due to sporadic or spontaneous mtDNA or nDNA mutations or due to exogenous noxious influences like drugs, toxins or infections and these disorders have various clinical presentations. It is believed that >95% of the MCPs are caused by nDNA mutations. In this paper, we present a case of adult onset pure mitochondrial myopathy. A46 year-old male had complaints of exertional dyspnea which progressively developed in twelve years, palpitation, bilateral eyelid drooping and proximal muscle weakness. Serum CPK, lactate, piruvate and lactate/piruvate levels of the patient were high. There was mild-moderate restrictive respiratory distress. Myogenic pattern was found in EMG. The diagnosis was established by mitochondrial accumulation in subsarcolemmal regions ["ragged red fiber" (RRF)] in many and the lack of COX activity in a small number of muscle fibers. Common deletion has been found in genetic analysis. The patient was accepted as adult onset pure mitochondrial myopathy, as he had only muscle findings clinically and pathologically.