Additionally, although the majority of studies reporting associations with probe cg03636183 have not used other biomarkers to confirm exposure to smoking, at least two used cotinine [45,46]. In addition, several studies controlled for blood cell mixture in their analyses, strengthening their findings [23,24,42,45,47,48,49]. Confirmatory sequencing or spectrometry were done in four of the studies [46,49,50,52] and confirmatory qPCR in one [27].
