ALZHEIMER-TYPE PATHOLOGY IN A PATIENT WITH MITOCHONDRIAL MYOPATHY, ENCEPHALOPATHY, LACTIC-ACIDOSIS AND STROKE-LIKE EPISODES (MELAS)

A 53-year-old Japanese woman with a point mutation in mitochondrial DN A (tRNA(Leu(UUR)), nt3243) consistent with mitochondrial myopathy, enc ephalopathy, lactic acidosis and stroke-like episodes (MELAS) and Alzh eimer-type brain pathology is reported. This woman had suffered myopat hy and psychosis without any clinical evidence of, stroke-like episode s during the last 10 years of her life, and had died after an accident . At autopsy 30 h post mortem, a part of the brain was snap frozen for biochemical and histochemical studies, and the remaining part was pro cessed for a routine examination and electron microscopy. In the brain there were no ischemic lesions. Instead, primitive/diffuse senile pla ques were found throughout the brain, predominantly in the frontal and temporal lobes, while Alzheimer neurofibrillary tangles were found on ly in the parahippocampal gyrus. These plaques were positive for beta- protein and mostly negative for tau protein, ubiquitin, neurofilaments , alpha-choline acetyltransferase, and acetylcholinesterase. Mutations in codon 331 of the ND2 gene as well as codons 693, 713 and 717 of th e beta-amyloid precursor protein gene, known to be responsible for som e cases of familial Alzheimer disease, were not found. Furthermore, co incidental Down syndrome was ruled out by chromosome analysis. The res ults suggest a possible correlation between this mitochondrial DNA abn ormality and Alzheimer-type pathology.