It is estimated that 0.5 to 1% of the general population carry an ATM variant classified as pathogenic for A-T disease, and studies conducted in hereditary breast and ovarian cancer families or early-onset breast cancer cases showed that such variants confer a 2 to 4-fold increase in breast cancer risk as compared to noncarriers [9,10,11]. The gene discussed is ATM; the disease is breast carcinoma.