MC1R and skin neoplasm: Participants enrolled at baseline who did not complete at least one follow-up survey were more likely to be younger, male, non-White, have lower levels of education and health literacy, have decreased belief that skin cancer prevention activities are effective, and have decreased perceived skin cancer risk and skin cancer worry, although specific predictors of questionnaire missingness differed according to MC1R risk category and follow-up timepoint (Supplementary Table S3).