HLA-DRB5 and dementia: It should be noted that the co-twin control association between DNA methylation in HLA-DRB5 and dementia was largely driven by a single site, cg13022993, with a substantially stronger association in the co-twin control model (β = 1.20, P = 0.004) than in the full sample (β = 0.26, P = 0.074), while associations at other sites were weakened (Supplementary table S2b).