CHEK2 and breast cancer: Furthermore, although a complete absence of somatic TP53 PVs was observed in breast cancers with heterozygous CHEK2 gPVs (n = 3), non-breast cancers with heterozygous CHEK2 gPVs did present with somatic TP53 PVs (Figure 1, D; Supplementary Figure 3, D, available online).