Abstract
BACKGROUND AND AIMS: Electronic cigarette use has escalated rapidly in recent years, particularly among youth. Little is known about the genetic influences on e-cigarette use. This study aimed to determine whether genetic risk for regular use of combustible cigarettes or for number of cigarettes smoked per day confers risk for ever e-cigarette use or frequency of e-cigarette use. DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: We used data from 9541 young adults from the Spit for Science longitudinal cohort study (2011-2019). Polygenic scores (PGS) of regular combustible cigarette use (PGS-RCU) and cigarettes per day (PGS-CPD) were constructed using summary statistics from the two largest available genome-wide association study (GWAS) meta-analysis of European ancestry and East Asian ancestry of combustible cigarette use and used to test whether the PGS of RCU or CPD predicted lifetime e-cigarette use and frequency of past 30-day e-cigarette use in a diverse sample of young adults of African (AFR), Admixed American (AMR), East Asian (EAS), European (EUR), and South Asian (SAS) ancestry. FINDINGS: The PGS-RCU was associated with lifetime e-cigarette use in the EUR sample (OR = 1.27, 95% CI = 1.19-1.36, P = 7.53 × 10(-12) ), but not in the other subsamples (ps > 0.12). This association remained significant after excluding regular combustible cigarette smokers (OR = 1.21, 95% CI = 1.12-1.31, P = 3.36 × 10(-6) ). There was no statistically significant association between PGS-CPD and lifetime e-cigarette use and neither the PGS-RCU nor the PGS-CPD were associated with frequency of e-cigarette use in the past 30 days in any of the subsamples. CONCLUSIONS: Genetic factors associated with regular combustible cigarette use appear to be associated with ever e-cigarette use in young adults. We did not find evidence for shared genetic factors influencing heaviness of use of combustible cigarettes and current e-cigarette use frequency.