For example, the heterozygous state of the CHEK2 1100delC variant, which predisposes carriers to breast cancer, is associated with an OR of 1.5-3.0 (corresponding to a lifetime risk of 20-25%), while the homozygous state is associated with a greater than fourfold increase in the lifetime risk compared with the general population [31,32]. Here, CHEK2 is linked to breast cancer.