Mutaciones en BRCA1 y BRCA2 en pacientes con historia familiar de cáncer de mama

Genomic Disparities in Breast Cancer Among Latinas

BACKGROUND

Breast cancer is the most common cancer diagnosed among Latinas in the United States and the leading cause of cancer-related death among this population. Latinas tend to be diagnosed at a later stage and have worse prognostic features than their non-Hispanic white counterparts. Genetic and genomic factors may contribute to observed breast cancer health disparities in Latinas.

METHODS

We provide a landscape of our current understanding and the existing gaps that need to be filled across the cancer prevention and control continuum.

RESULTS

We summarize available data on mutations in high and moderate penetrance genes for inherited risk of breast cancer and the associated literature on disparities in awareness of and uptake of genetic counseling and testing in Latina populations. We also discuss common genetic polymorphisms and risk of breast cancer in Latinas. In the treatment setting, we examine tumor genomics and pharmacogenomics in Latina patients with breast cancer.

CONCLUSIONS

As the US population continues to diversify, extending genetic and genomic research into this underserved and understudied population is critical. By understanding the risk of breast cancer among ethnically diverse populations, we will be better positioned to make treatment advancements for earlier stages of cancer, identify more effective and ideally less toxic treatment regimens, and increase rates of survival.

Low prevalence of BRCA1 and BRCA2 mutations in the sporadic breast cancer of Spanish population

The true prevalence of BRCA1/BRCA2 (BRCAs) germline mutations in sporadic breast or ovarian cancer (SBC/SOC) in Caucasian population is not well established. The aim of the study is to establish the prevalence of BRCAs mutations in SBC to ponder its relevance in the programs of genetic counseling in cancer and to explore the genotype-phenotype relationship of these particular breast cancers. The study was performed in 495 SBC. We sought 46 BRCA1 and 53 BRCA2 pathogenic mutations reported in the Spanish population. We followed a high resolution melting method performed in the LightCycler 480 (Roche Diagnostics) for the screening of these Spanish mutations using 49 primer pairs. Eight different deleterious mutations, one of them novel, were detected in nine patients, five without family history of BC/OC, what yields a true prevalence of 1.05% for BRCAs mutations in SBC. Furthermore, we found 18 unknown variants. Larger tumour size (T > 1) and earlier presentation are the independent parameters associated with the presence of BRCAs pathogenic mutations in SBC (P < 0.01) and the BRCA1 mutations carriers develop steroid-receptors negative tumors. Our results indicate that the true prevalence of BRCAs germline deleterious mutations in SBC of Spaniards is low. However, this does not lessens its relevance since the presence of BRCAs mutations in SBC could represent circa 16% of total BRCAs mutations detected in BC. SBCs of BRCAs mutation carriers have phenotype more aggressiveness than SBC without BRCAs mutation.

High-resolution melting analysis for rapid screening of BRCA1 and BRCA2 Spanish mutations

The majority of BRCA1 and BRCA2 mutation detection procedures include screening methods, all of which are time-consuming. High-resolution melting (HRM) is a promising pre-screening method of gene scanning that combines simplicity and rapid identification of genetic variants. We evaluated HRM in the screening of BRCA1/2 Spanish mutations. We studied 40 BRCA1 and 47 BRCA2 DNA samples with different Spanish mutations. We included a group of 20 unknown DNAs from patients with sporadic breast cancer (BC). The assay was performed with the LightCycler 480 Instrument (Roche). The HRM discriminates all the BRCA1/2 Spanish mutations studied from wild-type DNA. Besides, 54 out of 87 mutations were clearly differentiated from each other. In sporadic BC 11 polymorphisms and three unclassified variants were found in both genes. HRM is a valuable method for rapid screening of BRCA1/2 Spanish mutations and is capable of differentiating new genetic variants in PCR products.

Genetic analysis of BRCA1 and BRCA2 in breast/ovarian cancer families from Aragon (Spain): two novel truncating mutations and a large genomic deletion in BRCA1

We screened BRCA1 and BRCA2 germline mutations in 60 high-risk breast and/or ovarian cancer patients and 20 relatives from Aragon (Spain) by DHPLC (Denaturing High Performance Liquid Chromatography) and direct sequencing of the entire coding sequence and the splicing sites of both genes. We have identified 17 different pathogenic mutations: 8 in BRCA1 and 9 in BRCA2 in 60 unrelated patients and 50% of relatives were carriers. The prevalence of pathogenic mutations in this study was 33.33%. Two truncating mutations are novel: c.5024_5025delGA in exon 16 of BRCA1 and c.2929delC in exon 11 of BRCA2 (numbered after GenBank U14680 and U43746). Multiplex Ligation Dependent Probe Amplification (MLPA) was performed for large mutational scanning of both genes and a large genomic deletion in BRCA1 was found (DelEx8-13). Furthermore, five mutations are described for the first time in Spanish population: c.1191delC, c.3478_3479delTT and c.6633_6637delCTTAA (BRCA1) and c.3972_3975delTGAG and 3908_3909delTG (BRCA2). Three mutations have been reported previously once in Spain: c.3600_3610del11 (BRCA1), c.5804_5807delTTAA (BRCA2) and c.9246C>A (BRCA2). The mutation c.5374_5377delTATG has been found before only in two unrelated families from Castilla-Leon, Spain (BRCA2). Frequent mutations described in Spanish population have also been present: c.187_188delAG, c.5242C>A and c.5385insC in BRCA1 and c.3492_3493insT and c.9254_9258delATCAT in BRCA2. c.5242C>A, 3972_3975delTGAG and c.5804_5807delTTAA were the recurrent mutations found. Fifteen different unclassified variants were identified (25% families). Although specific BRCA1 and BRCA2 mutations are recurrently reported as a result of genetic founder effects we conclude that heterogeneous ethnicity increases the variety of mutations that can be found in Spanish populations.

Genes de susceptibilidad al cáncer de mama

Five percent of all cases of breast cancer (BC) show a hereditary component related to gene mutations with an autosomic dominant transmission. To date, few genes are known to be responsible of hereditary BC. The germline mutations of BRCA1 or BRCA2 genes account for less than 50% of families with breast/ovarian cancer predisposition. The large percentage of families with multiple cases of female BC and no BRCA1 and BRCA2 mutations detected could be attributed to the existence of other high or low susceptibility genes acting together with lifestyle risk factors. The predisposition to BC in carriers of ATM mutations has been documented previously. Due to the frequency of ATM heterozygotes in the general population, the mutations in this gene could be associated with up to 5% of BC cases. The mutation 1100delC of the CHEK2 gene seems to be a low penetrance allele of BC susceptibility. The objective of the present manuscript is to review some of the susceptibility genes identified to date.