KLKB1 and Alzheimer disease: Variants in KLKB1 or F12 were not identified in the largest GWAS of AD to date [3], although the kallikrein-kinin system is overactivated in the plasma, CSF, and frontal and temporal cortices of AD cases [90, 92, 93] and is most prominently expressed in brain regions with the earliest signs of AD [94].