Associations of NPPA promoter true methylation and hydroxymethylation with ischemic stroke and its functional outcome

Background Atrial natriuretic peptide (ANP) has been associated with
ischemic stroke (IS), but the underlying molecular mechanisms are not
clear. The objective of this study was to examine whether DNA methylation
and hydroxymethylation in the coding gene of ANP (NPPA) were associated
with IS, as well as its functional outcome. Methods and Results DNA
methylation and hydroxymethylation in NPPA promoter region were quantified
by targeted bisulfite sequencing and APOBEC-coupled epigenetic sequencing,
respectively, in 615 IS patients and 610 age- and sex-matched healthy
controls. True methylation was calculated as the quantified methylation
level minus the quantified hydroxymethylation level. The functional
outcome of IS was evaluated by the modified Rankin Scale (mRS) at a
3-month follow-up visit after onset. Multiple testing was controlled by
the false discovery rate approach. Of the nine CpG sites assayed,
hypomethylation at eight CpGs was not only associated with an increased
risk of having IS but also predicted a higher mRS score after onset (all
q<0.05) and hydroxymethylation at one CpG located at Chr1:11908348
was positively associated with IS (OR=1.39, 95%CI:1.15-1.68,
q<0.05), after adjusting for covariates and multiple testing.
While, hydroxymethylation levels at none of the CpGs assayed were
significantly associated with the mRS score. Conclusions DNA methylation
and hydroxymethylation in NPPA promoter were associated with the risk of
IS and its functional outcome in Chinese adults.