The significant increase in median Klotho levels was associated with the AD-MCI group (carriers, 936.6 pg/mL [range, 501.7-1563.5 pg/mL]; noncarriers, 790.1 pg/mL [range, 351.9-2733.8 pg/mL]; P = .006) and was not present in the AD-dementia group. This evidence concerns the gene KL and Alzheimer disease.