Screening of CHEK2 and TP53 p.R337H germ-line mutations in high-risk patients for hereditary breast and ovarian cancer from northeast of Brazil.

Abstract

1539 Background: CHEK2 is a molecular messenger that interacts with a checkpoint network of other susceptibility genes like ATM, BRCA1, TP53, MDM2, Cdc25A and Cdc25C. The mission of these checkpoints is to preserve the genome integrity during the cell division by regulating the cellular response to DNA damages. The TP53 p.R337H germline mutation was studied in patients with Li-Fraumeni Syndrome, breast cancer and Choroid plexus carcinomas in Southern of Brazil, but never in the Northeast. In the hereditary breast cancer the mutation frequencies of susceptibility genes of low penetrance like CHEK2 is 1-10%, while for genes of high penetrance as TP53 is <1%. Thus, the aim of this study was to screening for CHEK2 and TP53 most common germline mutations in high-risk patients for hereditary breast and ovarian cancer (HBOC) from Northeast of Brazil. Methods: It was analyzed 100 high-risk patients for HBOC from Bahia, Brazil. The genomic DNA was extract from peripheral blood. The CHEK2 mutations, c.1100delC, c.444+1G>A and p.I157T, and TP53 p.R337H mutation were genotyped by Allelic Specific-PCR or PCR-RFLP. Results: Most of the subjects had only breast cancer (86.0%), followed by ovarian (7.0%) and both breast and ovarian cancer (7.0%). Among the breast cancer cases the most common histological type was the ductal (71.0%), while among the ovarian cancer cases were the serous (57.14%). The mean age at diagnostic was 42 yrs (± 9.99). Any of the patient presented c.1100delC, c.444+1G>A and p.I157T mutations. But, two have the p.R337H mutation. Conclusions: Though there is the hypothesis that mutations of low penetrance genes, such as CHEK2, are more likely to be found than high penetrance genes, such as TP53, here it was demonstrate that three of most predisposing variants of CHEK2, c.1100delC, c.444+1G>A and p.I157T, do not have major contribution in HBOC in the population studied. While, the p.R337H, though presented in low frequency compared with the Southern of Brazil (Ashton-Prolla et al., 2012), seems to have a significant contribution in HBOC.