Haplotype analyses of the c.1027C>T and c.2167_2168delAT recurrent truncating mutations in the breast cancer-predisposing gene PALB2.

PURPOSE: Breast cancer-predisposing mutations PALB2 c.1027C>T (p.Gln343*) and PALB2 c.2167_2168delAT have each been observed multiple times in breast cancer families of Italian ancestry. More recently, the c2167_2168delAT mutation was identified in unrelated breast cancer cases of various ancestries. For each mutation, we investigated whether the origin was multiple mutational events (a "hot-spot") or a single event (a founder allele). METHODS: We genotyped and reconstructed haplotypes for 36 participants of Italian, Italian-American, Hispanic, and Nigerian ancestries, using seven short tandem repeat (STR) markers that covered 3 Megabases within and flanking PALB2 on chromosome 16. RESULTS: For PALB2 c.1027C>T, a shared haplotype with a minimum size of 150 kb was shared by all 19 carriers investigated, all of Italian ancestry. This result suggests that this allele arose as a single event in a shared ancestor. For PALB2 c.2167_2168delAT, all 12 carriers from American-Italian and Italian families shared a 1-Mb haplotype, the 3 Hispanic carriers shared a different haplotype of size 2 Mb, and the Nigerian carrier had different alleles at all 7 STR markers. These results suggest that PALB2 c.2167_2168delAT arose multiple times, but that within each population, PALB2 c.2167_2168delAT likely represents a single mutational event. CONCLUSION: We identified two PALB2 mutations that are founder alleles in Italian families, one of which is, independently, also a founder mutation in American-Hispanic breast cancers.

A BRCA1 promoter variant (rs11655505) and breast cancer risk.

BACKGROUND: A study of Chinese women recently suggested that the minor allele of rs11655505 in the BRCA1 promoter (c.-2265C-->T) increases promoter activity and has a protective effect on breast cancer risk. METHODS: We genotyped rs11655505 in 2912 female breast cancer cases and 2783 unaffected female controls from four Caucasian breast cancer studies. RESULTS: No evidence for an association between rs11655505 and breast cancer risk was found. CONCLUSIONS: Our study failed to confirm a role of rs11655505 in breast cancer risk. Larger studies are necessary to determine if there is a weak association between this SNP and breast cancer risk.

Towards population-based genetic screenings for breast and ovarian cancer: A comprehensive review from economic evaluations to patient perspectives.

Genetic testing for hereditary breast and ovarian cancer following genetic counseling is based on guidelines that take into account particular features of the personal and family history, and clinical criteria conferring a probability of having a BRCA mutation greater than 10% as a threshold for accessing the test. However, besides reducing mortality and social impact, the extension of screening programs also for healthy family members would allow a huge saving of the rising costs associated with these pathologies, supporting the choice of the "Test" strategy versus a "No Test" one. Analyses of different health care systems show that by applying the "Test" strategy on patients and their families, a decrease in breast and ovarian cancer cases is achieved, as well as a substantial decrease in costs of economic resources, including the costs of the clinical management of early detected tumors. In this review, we analyzed the most recent papers published on this topic and we summarized the findings on the economic evaluations related to breast and ovarian cancer population screenings. These results proved and validated that the population-wide testing approach is a more accurate screening and preventive intervention than traditional guidelines based on personal/family history and clinical criteria to reduce breast and ovarian cancer risk.

Evaluation of SNPs in miR-146a, miR196a2 and miR-499 as low-penetrance alleles in German and Italian familial breast cancer cases.

Recently, the SNPs rs11614913 in hsa-mir-196a2 and rs3746444 in hsa-mir-499 were reported to be associated with increased breast cancer risk, and the SNP rs2910164 in hsa-mir-146a was shown to have an effect on age of breast cancer diagnosis. In order to further investigate the effect of these SNPs, we genotyped a total of 1894 breast cancer cases negative for disease-causing mutations or unclassified variants in BRCA1 and BRCA2, and 2760 controls from Germany and Italy. We compared the genotype and allele frequencies of rs2910164, rs11614913 and rs3746444 in cases versus controls of the German and Italian series, and of the two series combined; we also investigated the effect of the three SNPs on age at breast cancer diagnosis. None of the performed analyses showed statistically significant results. In conclusion, our data suggested lack of association between SNPs rs2910164, rs11614913 and rs3746444 and breast cancer risk, or age at breast cancer onset.

Comparative in vitro and in silico analyses of variants in splicing regions of BRCA1 and BRCA2 genes and characterization of novel pathogenic mutations.

Several unclassified variants (UVs) have been identified in splicing regions of disease-associated genes and their characterization as pathogenic mutations or benign polymorphisms is crucial for the understanding of their role in disease development. In this study, 24 UVs located at BRCA1 and BRCA2 splice sites were characterized by transcripts analysis. These results were used to evaluate the ability of nine bioinformatics programs in predicting genetic variants causing aberrant splicing (spliceogenic variants) and the nature of aberrant transcripts. Eleven variants in BRCA1 and 8 in BRCA2, including 8 not previously characterized at transcript level, were ascertained to affect mRNA splicing. Of these, 16 led to the synthesis of aberrant transcripts containing premature termination codons (PTCs), 2 to the up-regulation of naturally occurring alternative transcripts containing PTCs, and one to an in-frame deletion within the region coding for the DNA binding domain of BRCA2, causing the loss of the ability to bind the partner protein DSS1 and ssDNA. For each computational program, we evaluated the rate of non-informative analyses, i.e. those that did not recognize the natural splice sites in the wild-type sequence, and the rate of false positive predictions, i.e., variants incorrectly classified as spliceogenic, as a measure of their specificity, under conditions setting sensitivity of predictions to 100%. The programs that performed better were Human Splicing Finder and Automated Splice Site Analyses, both exhibiting 100% informativeness and specificity. For 10 mutations the activation of cryptic splice sites was observed, but we were unable to derive simple criteria to select, among the different cryptic sites predicted by the bioinformatics analyses, those actually used. Consistent with previous reports, our study provides evidences that in silico tools can be used for selecting splice site variants for in vitro analyses. However, the latter remain mandatory for the characterization of the nature of aberrant transcripts.

Germline mutations in BRIP1 and PALB2 in Jewish high cancer risk families.

Germline mutations in BRCA1 and BRCA2 account for ~30 % of inherited breast cancer. BRIP1 and PALB2 are likely genes for breast cancer susceptibility, based on their roles in maintaining cellular integrity. Indeed, few pathogenic germline mutations in both genes are reported in ethnically diverse breast cancer families. There is a paucity of data on the putative contribution of both genes to inherited breast cancer in Jewish high risk families. High risk Jewish women, none of whom was a carrier of the predominant Jewish mutations in BRCA1/BRCA2, were screened for BRIP1 germline mutations by combined denaturing gradient gel electrophoresis, high resolution melting and sequencing. Direct sequencing of exons and flanking intronic sequences was used for PALB2 mutational analysis. Overall, 149 women, all of high risk, cancer prone families of Ashkenazi origin, were genotyped for BRIP1 mutations: 127 with breast cancer, 22 with ovarian cancer. No truncating mutations were noted and one novel (p.Ala745Thr) and two previously described missense mutations were detected. For PALB2, 93 women were genotyped (87 with breast cancer) of Ashkenazi (n = 32) and non Ashkenazi Jewish origin. Fifteen sequence variants were detected, of these, none was truncating, four were not previously reported, and two (p.Asp871Gly and p.Leu1119Pro) were seemingly pathogenic based on the PolyPhen2 protein prediction algorithm. These missense mutations were not detected in any of 113 healthy Ashkenazi and 109 Moroccan, cancer free controls. In conclusion, germline mutations in BRIP1 and PALB2 contribute marginally to breast cancer susceptibility in ethnically diverse, Jewish high risk families.

Sequencing analysis of SLX4/FANCP gene in Italian familial breast cancer cases.

Breast cancer can be caused by germline mutations in several genes that are responsible for different hereditary cancer syndromes. Some of the genes causing the Fanconi anemia (FA) syndrome, such as BRCA2, BRIP1, PALB2, and RAD51C, are associated with high or moderate risk of developing breast cancer. Very recently, SLX4 has been established as a new FA gene raising the question of its implication in breast cancer risk. This study aimed at answering this question sequencing the entire coding region of SLX4 in 526 familial breast cancer cases from Italy. We found 81 different germline variants and none of these were clearly pathogenic. The statistical power of our sample size allows concluding that in Italy the frequency of carriers of truncating mutations of SLX4 may not exceed 0.6%. Our results indicate that testing for SLX4 germline mutations is unlikely to be relevant for the identification of individuals at risk of breast cancer, at least in the Italian population.