CHEK2 and breast carcinoma: In contrast to the typical moderate risks attributed to CHEK2 GPVs, primarily based on this truncating CHEK2 1100delC founder GPV, there is another common European founder missense GPV, c.470T>C (p.Ile157Thr), herein referred to as “I157T” [15], which imparts a breast cancer risk of less than 20% and RR ~ 1.3 [14,16].