MT-CO2 and early-onset autosomal dominant Alzheimer disease: Analysis of mitochondrial cytochrome c oxidase II gene obtained from blood samples revealed that 4 nonrelated patients with probable AD harbored the polymorphism A8027G (three of them were diagnosed with late onset Alzheimer's disease, with familial history of the disease and one of them with early onset Alzheimer's disease) (Tables 1 and 2).