Suzuki Y, Goto Y, Taniyama M, Nonaka I, Murakami N, Hosokawa K, Asahina T, Atsumi Y, Matsuoka K
Saiseikai Central Hospital, Minato-ku, Tokyo, Japan.
J Neurol Sci. 1997 Jan;145(1):49-53. doi: 10.1016/s0022-510x(96)00239-0.
Diabetes mellitus associated with 3243 mitochondrial tRNA(Leu(UUR)) mutation (DM-Mt3243) is a subtype of the mitochondrial multisystem syndromes, usually lacking myopathy. Muscle biopsies were obtained from 5 patients with diabetes and one patient with impaired glucose tolerance, all possessing the 3243 mutation without hallmarks of MELAS. The specimens were subjected to histochemical, biochemical, and genetic analysis. Ragged-red fibers were seen in 4 of the 6 patients (67%), and focal cytochrome c oxidase deficiency in 3 (50%). Strongly succinate dehydrogenase-reactive blood vessels was found in 5 patients (83%). The histochemical signs were present even when the mutant percentage was very low. The percentage of mutant DNA was almost always higher in muscles than in leukocytes. The combination of allele specific PCR amplification and PCR-RFLP method was useful to evaluate the mutant proportion. The mutant percentage in muscle was under 50% in 5 (83%) patients. Mitochondrial enzyme activity was deficient only in one patient. This study presents the detailed muscle histopathology in the DM-Mt3243 group. Abnormal histopathologic findings seemed similar to those noted in MELAS. However, mutant percentage in muscles was lower than that of MELAS, and respiratory chain enzyme activity was well preserved.
与3243线粒体tRNA（亮氨酸（UUR））突变相关的糖尿病（DM-Mt3243）是线粒体多系统综合征的一种亚型，通常无肌病表现。对5例糖尿病患者和1例糖耐量受损患者进行了肌肉活检，所有患者均存在3243突变，无MELAS特征。对标本进行了组织化学、生化和基因分析。6例患者中有4例（67%）可见破碎红纤维，3例（50%）存在局灶性细胞色素c氧化酶缺乏。5例患者（83%）发现琥珀酸脱氢酶反应性强的血管。即使突变比例非常低，组织化学征象依然存在。肌肉中突变DNA的比例几乎总是高于白细胞。等位基因特异性PCR扩增和PCR-RFLP方法相结合有助于评估突变比例。5例（83%）患者肌肉中的突变比例低于50%。仅1例患者线粒体酶活性缺乏。本研究展示了DM-Mt3243组详细的肌肉组织病理学情况。异常组织病理学发现似乎与MELAS中所见相似。然而，肌肉中的突变比例低于MELAS，呼吸链酶活性保存良好。
