CYP2R1 and cancer: An early MR analysis in 95,766 Danish participants (2,839 cancer deaths) suggested that higher levels of vitamin D (instrumented using 4 SNPs in DHCR7 or CYP2R1) may lower risk of cancer mortality (OR per 20 nmol/L higher plasma 25(OH)D: 0.70; 95% CI 0.50, 0.98), consistent with a meta-analysis of five trials (N = 1,591 deaths) showing that vitamin D supplementation (achieving a 54–135 nmol/L increase in circulating levels of circulating 25(OH)D in the intervention group) reduced total cancer mortality [relative risk (RR) 0.88; 95% CI 0.78, 0.98] [55, 57].