Furthermore, the brain of Alzheimer’s disease patients contains significantly lower KLK6 levels than the brain of nonaffected individuals (Zarghooni et al., 2002; Ashby et al., 2010); when the mRNA levels were quantified in the hippocampus they were also decreased (Shimizu-Okabe et al., 2001). This evidence concerns the gene KLK6 and Alzheimer disease.