SAMHD1 and breast cancer: At phenome-wide significance, SAMHD1 mutation carrier status was associated with approximately twofold increased risk of breast cancer (OR = 1.91; 95% CI, 1.52–2.40; p=2.7 × 10–8), as well as greater risk of ‘cancer (suspected or other)’ (OR = 1.52; 95% CI, 1.28–1.80; p=1.1 × 10–6; Figure 4B; Figure 4—source data 2).