As another example, expression of OSBP2 was strongly and positively associated with AD progression in ADNI peripheral blood samples50; the probe we identified as associated with D (cg15256322) lies very close to the transcription start site of OSBP2. This probe has a negative effect on D, i.e. lower values of methylation residuals associate with higher values of D. Based on our definition of D, a higher value of D implies either less phosphorylated tau proteins or more total tau proteins. Here, MAPT is linked to Alzheimer disease.