Other genes that include CHEK2, PTEN, TP53, ATM, STK11/LKB1, CDH1, NBS1, RAD50, BRIP1 and PALB2 have been described to be high or moderate penetrance breast cancer susceptibility genes, all contributing to the hereditary breast cancer spectrum.
Heterozygous mutations in the PALB2hereditary breast cancer predisposition gene impact on the three-dimensional nuclear organization of patient-derived cell lines.
PALB2 c.1676A > G (rs152451A/G) and c.2993C > T (rs45551636C/T) variants were significantly associated with increased BC risk only in cases with a strong family history of BC (OR = 1.9 [CI 95% 1.3-2.8] p < 0.01 and OR = 3.3 [CI 95% 1.4-7.3] p < 0.01, respectively).
Using Exome Aggregation Consortium control data, we confirm significant associations of heterozygous germ line mutations with BC for ATM (OR: 3.63, 95%CI: 2.67-4.94), CDH1 (OR: 17.04, 95%CI: 3.54-82), CHEK2 (OR: 2.93, 95%CI: 2.29-3.75), PALB2 (OR: 9.53, 95%CI: 6.25-14.51), and TP53 (OR: 7.30, 95%CI: 1.22-43.68).
As PALB2-deficient tumors were shown to be sensitive to Poly(ADP-ribose) Polymerase (PARP) inhibitors, our study has implications for newly developed, favorable treatment options in familial breast cancer.
Here we show, by screening for PALB2 mutations in Finland that a frameshift mutation, c.1592delT, is present at significantly elevated frequency in familial breast cancer cases compared with ancestry-matched population controls.
Loss-of-function mutations in PALB2 are an important cause of hereditary breast cancer, with respect both to the frequency of cancer-predisposing mutations and to the risk associated with them.
These variants were found in genes associated with known or suspected BC predisposition (PALB2, BARD1, CHEK2, RAD51C and FANCA) or in predisposing genes linked to other cancer types but not well-studied in the context of familial BC (EXO1, RECQL4, CCNH, MUS81, TDP1, DCLRE1A, DCLRE1C, PDE11A and RINT1) and genes associated with different hereditary syndromes but not yet clearly associated with familial cancer syndromes (ABCC11, BBS10, CD96, CYP1A1, DHCR7, DNAH11, ESCO2, FLT4, HPS6, MYH8, NME8 and TTC8).
Our results show that mutation analysis of the PALB2 gene, including the analysis of LGRs, is primarily indicated in patients with HBC in case of their BRCA1 and BRCA2 negativity.
Hence, our approach allowed us to specify BC relative risks associated with deleterious-predicted variants in PALB2, ATM and CHEK2 and to add MAST1, POLH, RTEL1 and FANCI to the list of DNA repair genes possibly involved in BC susceptibility.
In five patients (5 of 83; 6% of cohort), we detected causative pathogenic variants in established hereditary breast cancer susceptibility genes (i.e., PALB2, CHEK2, ATM).