They found that women with AT-associated ATM mutations treated previously with radiation had significantly greater risk of contralateral breast cancer than unexposed women either with no mutation (Gy < 1.0, RR = 2.8; Gy ≥ 1.0, RR = 3.3) or unexposed women with the same mutation (Gy < 1.0, RR = 5.3; Gy ≥ 1.0, RR = 5.8). The gene discussed is ATM; the disease is breast cancer.