De la Monte and Wands [89] examined postmortem brain tissue from AD patients with different degrees of severity and found that the severity of AD was related to impairments in mitochondrial gene expression, namely in complex IV of the mitochondrial respiratory chain, increased levels of p53 and molecular indexes of oxidative stress, such as up-regulation of nitric oxide synthase (NOS) and NADPH-oxidase (NOX). This evidence concerns the gene FMO5 and Alzheimer disease.