MELAS: a nationwide prospective cohort study of 96 patients in Japan.

BACKGROUND: MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) (OMIM 540000) is the most dominant subtype of mitochondrial myopathy. The aim of this study was to determine the prevalence, natural course, and severity of MELAS. METHODS: A prospective cohort study of 96 Japanese patients with MELAS was followed between June 2003 and April 2008. Patients with MELAS were identified and enrolled based on questionnaires administered to neurologists in Japan. MELAS was defined using the Japanese diagnostic criteria for MELAS. Two follow-up questionnaires were administered to neurologists managing MELAS patients at an interval of 5years. RESULTS: A prevalence of at least 0.58 (95% confidential interval (CI), 0.54-0.62)/100,000 was calculated for mitochondrial myopathy, whereas the prevalence of MELAS was 0.18 (95%CI, 0.02-0.34)/100,000 in the total population. MELAS patients were divided into two sub-groups: juvenile form and adult form. Stroke-like episodes, seizure and headache were the most frequent symptoms seen in both forms of MELAS. Short stature was significantly more frequent in the juvenile form, whereas hearing loss, cortical blindness and diabetes mellitus were significantly more frequent in the adult form. According to the Japanese mitochondrial disease rating scale, MELAS patients showed rapidly increasing scores (mean±standard deviation, 12.8±8.7) within 5years from onset of the disease. According to a Kaplan-Meier analysis, the juvenile form was associated with a higher risk of death than the adult form (hazard ratio, 3.29; 95%CI, 1.32-8.20; p=0.0105). CONCLUSIONS AND GENERAL SIGNIFICANCE: We confirmed that MELAS shows a rapid degenerative progression within a 5-year interval and that this occurs in both the juvenile and the adult forms of MELAS and follows different natural courses. This article is part of a Special Issue entitled: Biochemistry of Mitochondria.

A two-day-old hyperthyroid neonate with thyroid hormone resistance born to a mother with well-controlled Graves' disease: a case report.

INTRODUCTION: Resistance to thyroid hormone is a syndrome caused by thyroid hormone receptor ß mutations, which are usually inherited in an autosomal-dominant pattern. CASE PRESENTATION: Our patient, a Japanese neonate boy, showed hyperthyroid symptoms at age two days. Although our patient was diagnosed as having resistance to thyroid hormone, his hyperthyroid symptoms continued for two weeks. Therefore, our patient was treated with methimazole and iodine for two weeks from birth, showing no side effects and no symptoms upon treatment. At age 70 days, an R243W mutation in thyroid hormone receptor ß was detected in our patient; while absent in his mother, the mutation was present in his father, who never showed any symptoms. CONCLUSIONS: To the best of our knowledge this is the first case report of a resistance to thyroid hormone in a neonate presenting with hyperthyroid symptoms born to a mother with Graves' disease and treated with methimazole and iodine. These results suggest that methimazole and iodine may be a good short-term option for treatment.