Placebo controlled double blind randomized Phase II Clinical Trial of sodium pyruvate on lactic acidosis associated with mitochondrial disorders

INTERVENTION: Intervention type:DRUG. Intervention1:sodium pyruvate, Dose form:GRANULES, Route of administration:ORAL, intended dose regimen:0.5g/kg/day TID ., Route of administration:ORAL, Route of administration:ORAL Control intervention1:Lactose + NaCl, Dose form:GRANULES, Route of administration:ORAL, Intended dose regimen:0.17g/kg/day TID. CONDITION: lactic acidosis associated with mitochondrial disorders PRIMARY OUTCOME: JMDRS section 1 & 2. Timepoint:24 weeks; . SECONDARY OUTCOME: NMDAS section 1‐3, brain lactate by MRS, GDF15. Timepoint: 24 weeks; . INCLUSION CRITERIA: mitochondrial disease who fulfilled the following criteria 1) patient whoes age is over than 6 years‐old 2) patient who are fulfilled the diagnostic criteria of MELAS/MELA 3) patientwho has an A3243G mutation. 4) no past history of sodium pyruvate administration for the therapeutic purpose 5) patient whose score of section 1+2 by JMDRS is more than 10, and one of the specific score is more than 2. 6) patient who have a written informed conscent or ascent by his/her own opinion.