Five of these genes were discovered in our case-case analysis of any 2+ primary cancers: SLC6A2 (OR [95% CI] = 1.86 [1.42, 2.41], p = 3.90 × 10−6), ATM (OR [95% CI] = 1.42 [1.15, 1.77], p = 1.10 × 10−3), CHEK2 (OR [95% CI] = 1.56 [1.23, 1.98], p = 2.31 × 10−4), SAMHD1 (OR [95% CI] = 1.56 [1.14, 2.13], p = 5.34 × 10−3), and BRCA2 (OR [95% CI] = 1.86 [1.31, 2.65], p = 5.42 × 10−4). Here, SLC6A2 is linked to cancer.