At this locus, a single CpG probe has emerged consistently: cg03636183. This review identified 12 studies that included the probe among their list of significant results. Of those, the probe was the most significant finding in three [46,47,48], all of which used the 27k platform for discovery. Although subsequent studies with the 450k platform have not typically identified this probe as the most significantly associated with smoking, the overall finding has replicated in a number of these studies. The probe has been shown to be hypomethylated in adult smokers across a broad age range [27,28,46,47,48,49,50,51,52,53,54]. The probe is associated with smoking in studies in both men and women, men only [28], and women only [27,50,53,54]. The association is present in individuals of African ancestry [27,48], South Asian ancestry [28], and Arab ancestry [55] in addition to European ancestry.
