Lorenzoni Paulo José, Scola Rosana H, Kay Cláudia S Kamoi, Arndt Raquel C, Freund Aline A, Bruck Isac, Santos Mara Lúcia S F, Werneck Lineu C
Internal Medicine Department, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Arq Neuropsiquiatr. 2009 Sep;67(3A):668-76. doi: 10.1590/s0004-282x2009000400018.
The aim of the study was to analyze a series of Brazilian patients suffering from MELAS.
Ten patients with MELAS were studied with correlation between clinical findings, laboratorial data, electrophysiology, histochemical and molecular features.
Blood lactate was increased in eight patients. Brain image studies revealed a stroke-like pattern in all patients. Muscle biopsy showed ralled-red fibers (RRF) in 90% of patients on modified Gomori-trichrome and in 100% on succinate dehydrogenase stains. Cytochrome c oxidase stain analysis indicated deficient activity in one patient and subsarcolemmal accumulation in seven patients. Strongly succinate dehydrogenase-reactive blood vessels (SSV) occurred in six patients. The molecular analysis of tRNA (Leu(UUR)) gene by PCR/RLFP and direct sequencing showed the A3243G mutation on mtDNA in 4 patients.
The muscle biopsy often confirmed the MELAS diagnosis by presence of RRF and SSV. Molecular analysis of tRNA(Leu(UUR)) gene should not be the only diagnostic criteria for MELAS.
本研究旨在分析一系列患有线粒体脑肌病伴乳酸血症和卒中样发作（MELAS）的巴西患者。
对10例MELAS患者进行了研究，分析了临床症状、实验室检查数据、电生理学、组织化学和分子特征之间的相关性。
8例患者血乳酸升高。脑部影像学研究显示所有患者均有卒中样表现。肌肉活检显示，改良Gomori三色染色法中90%的患者出现破碎红纤维（RRF），琥珀酸脱氢酶染色法中100%的患者出现RRF。细胞色素c氧化酶染色分析表明，1例患者活性缺乏，7例患者肌膜下积聚。6例患者出现强琥珀酸脱氢酶反应性血管（SSV）。通过聚合酶链反应/限制性片段长度多态性分析（PCR/RLFP）和直接测序对tRNA（Leu（UUR））基因进行分子分析，结果显示4例患者线粒体DNA（mtDNA）存在A3243G突变。
肌肉活检常通过RRF和SSV的存在来确诊MELAS。tRNA（Leu（UUR））基因的分子分析不应作为MELAS的唯一诊断标准。
