ACE2 and COVID-19: Next, when examining X-linked candidate loci, we found that one CpG site in ACE2 (cg21598868, p value ≤ 0.05) was differentially methylated by COVID-19 status in both sexes, although females (Δβ = 0.061), had a larger effect size than males (Δβ = 0.037) (Fig. 7B).