Association of the BRCA1 promoter polymorphism rs11655505 with the risk of familial breast and/or ovarian cancer.

Germline mutations in the BRCA1 tumor suppressor gene predispose affected individuals to breast cancer; however, incomplete cancer penetrance and the presence of phenocopies in BRCA1 families also indicate genetic and environmental modifiers of breast cancer risk. In this study, we have tested the single nucleotide polymorphism rs1655505 of the BRCA1 promoter, as candidate for the modifier of breast cancer risk. The polymorphic variants were genotyped in BRCA1-negative (729), familial breast and/or ovarian cancer cases (FBOC), including cases with a reported maternal history (154), nonfamilal (sporadic) cases (600), hereditary breast/ovarian cases with BRCA1 mutations (190) and population controls (1,590) from Central Poland. An association with the risk of FBOC was observed for the minor (T) allele and (TT) genotype (T: p = 0.006, OR = 1.40, 95% CI = 1.10-1.79; TT: p = 0.001, OR = 2.23, 95% CI = 1.37-3.62) in female cases with a reported maternal history, specifically in women with the onset of disease after 50 years of age (T: p = 0.004, OR = 1.77, 95% CI = 1.20-2.62; TT: p = 0.001, OR = 3.7, 95% CI = 1.62-8.46). The presented evidence suggests a need to conduct larger studies on the association between genetic variations at the BRCA1 promoter and the breast cancer risk, according to maternal/paternal lineage.

Risk profiles and penetrance estimations in multiple endocrine neoplasia type 2A caused by germline RET mutations located in exon 10.

Multiple endocrine neoplasia type 2 is characterized by germline mutations in RET. For exon 10, comprehensive molecular and corresponding phenotypic data are scarce. The International RET Exon 10 Consortium, comprising 27 centers from 15 countries, analyzed patients with RET exon 10 mutations for clinical-risk profiles. Presentation, age-dependent penetrance, and stage at presentation of medullary thyroid carcinoma (MTC), pheochromocytoma, and hyperparathyroidism were studied. A total of 340 subjects from 103 families, age 4-86, were registered. There were 21 distinct single nucleotide germline mutations located in codons 609 (45 subjects), 611 (50), 618 (94), and 620 (151). MTC was present in 263 registrants, pheochromocytoma in 54, and hyperparathyroidism in 8 subjects. Of the patients with MTC, 53% were detected when asymptomatic, and among those with pheochromocytoma, 54%. Penetrance for MTC was 4% by age 10, 25% by 25, and 80% by 50. Codon-associated penetrance by age 50 ranged from 60% (codon 611) to 86% (620). More advanced stage and increasing risk of metastases correlated with mutation in codon position (609→620) near the juxtamembrane domain. Our data provide rigorous bases for timing of premorbid diagnosis and personalized treatment/prophylactic procedure decisions depending on specific RET exon 10 codons affected.

The frequency of selected polymorphic variants of the RET gene in patients with medullary thyroid carcinoma and in the general population of central Poland.

The object of this work was to compare the frequency of three polymorphic changes in the RET proto-oncogene: L769L, S836S, and S904S in patients with medullary thyroid carcinoma (MTC; n = 246) and in the general population (n = 420 for single-nucleotide polymorphism [SNP] L769L and S904S; n = 411 for SNP 836). We tried to investigate how the harbored SNPs affect the age at onset of sporadic medullary thyroid carcinoma (sMTC) and MTC in carriers of known pathogenic mutations at codons 634 and 791 of the RET gene. A statistically significant difference was found in the frequency of the heterozygous change L769L in patients with sMTC (48.3%) and in unaffected individuals (39.5%). The presence of the polymorphic change L769L in the RET gene predisposes to the development of sMTC and also lowers the age of onset of MTC in carriers of the homozygous polymorphic variant L769L. The presence of this polymorphic change in MTC patients carrying, at the same time, the RET codon 634 mutation lowers the age of onset of MTC in this group.

Novel germline mutations in BRCA2 gene among breast and breast-ovarian cancer families from Poland.

Identification of mutations in the BRCA2 gene and estimation of their clinical consequences for women and men treated in the Maria Sklodowska-Curie Memorial Cancer Center Warsaw, Poland in the years 1998-2008. The probands (97 women and 8 men) had a family history of breast and ovarian cancer (median age 46). The presence of molecular changes was examined in DNA isolated from peripheral blood lymphocytes. Germline mutations in 27 exons of the BRCA2 gene were screened by 'touchdown' PCR amplification, DHPLC and sequencing. Missense mutations were classified by multiple-sequences alignments of orthologous BRCA2 protein sequences with T-Coffee software. 39 molecular changes (8 novel) were identified in the BRCA2 gene in 105 investigated patients. In 12 patients the following pathogenic mutations were identified: 5467insT, 6174delT, 6192delAT, 6675delTA, 8141del5, 9152delT, 9326insA, 9631delC, IVS23-2A > G and E394X. The presence of 10 missense type mutations was detected including the following: D1420O, T1915 M, N3124I. The determination of pathogenic status of molecular variants detected in BRCA2 gene, described in the BIC mutation database as 'UV' depends on many parameters. Important is the assessment of the evolutionary conservation of their protein sequences and studying of the frequency of molecular variants detected in breast cancer patients and in population. A high diversity was found of the pathogenic mutations detected in BRCA2 gene in the Polish population.

Age at onset of bilateral breast cancer, the presence of hereditary BRCA1, BRCA2, CHEK2 gene mutations and positive family history of cancer.

BACKGROUND: Our research focused on the relations between the age at onset of bilateral breast cancer and the prevalence of selected hereditary BRCA1, BRCA2 and CHEK2 gene mutations with reference to their positive family history of cancer. METHODS: The DNA of peripheral blood lymphocytes of patients was examined for the presence of selected hereditary mutations in the BRCA1, BRCA2 and CHEK2 genes, using molecular biology techniques. The family history of neoplasms was also analyzed. RESULTS: The following mutations in the BRCA1 gene were identified: 185delAG, C61G, 5382insC, 3875 del11ins7, and R1751X. In the BRCA2 gene, the 9631delC and A9599T mutations were found. In the CHEK2 gene, the 1100delC and I157T mutations were identified. BRCA1/2 gene mutations were identified in 19.4% of patients and CHEK2 gene mutations in 7%. CONCLUSIONS: It was shown that the presence of the mutations in the BRCA1/2 genes among patients with bilateral breast cancer is associated with an earlier occurrence of the first and the second breast cancer than in patients without hereditary mutations in these genes (a difference of 7.2-8.4 years). In patients with CHEK2 gene mutations, breast cancer occurred 2.1-3.8 years earlier than in patients without mutations in the CHEK2 gene.

[Clinical and genetic profile of patients with medullary thyroid cancer treated in the Cancer Centre--Institute of Oncology in Warsaw]. / Analiza kliniczna i genetyczna chorych na raka rdzeniastego tarczycy w Centrum Onkologii--Instytucie w Warszawie.

INTRODUCTION: The aim of this study was to analyse the distribution and frequency of mutations and their correlations with clinical phenotypes of patients with MTC, to reveal the differences between sporadic and familial type of MTC, and to describe the phenotypes of patients. MATERIALS AND METHODS: 212 patients with medullary thyroid cancer (MTC) were treated in Cancer Centre in Warsaw between 1997 and 2005. In most patients, DNA isolated from peripheral blood leukocytes was tested for RET gene mutations by sequencing and accordingly MTC form was assessed. Genetic testing was performed in the relatives of patients with familial MTC in order to distinguish asymptomatic mutation carriers from noncarriers. RESULTS: RET gene mutations were identified in 46 patients (22%). The others were found noncarriers and sporadic MTC was diagnosed. MEN 2A/FMTC syndrome (multiple endocrine neoplasia type 2A/ familial type of MTC) was diagnosed in 44 patients, MEN 2B syndrome (multiple endocrine neoplasia type 2B) in 2 patients. In patients with sporadic and familial MTC, age at diagnosis and multifocal occurrence was analysed, and the results were found to be in accordance with those of other research centres. However, the distribution and frequency of mutations, as well as some clinical data, such as the frequency of pheochromocytoma occurrence as the first manifestation of MEN syndrome, differed from the published data, and further studies are necessary to reveal the reasons of these differences. CONCLUSIONS: DNA testing for RET gene mutations is reliable as a diagnostic tool and therefore it should be performed for screening of all patients with MTC or other diseases of MEN syndrome.

Preliminary studies on DNA retardation by MutS applied to the detection of point mutations in clinical samples.

MutS ability to bind DNA mismatches was applied to the detection of point mutations in PCR products. MutS recognized mismatches from single up to five nucleotides and retarded the electrophoretic migration of mismatched DNA. The electrophoretic detection of insertions/deletions above three nucleotides is also possible without MutS, thanks to the DNA mobility shift caused by the presence of large insertion/deletion loops in the heteroduplex DNA. Thus, the method enables the search for a broad range of mutations: from single up to several nucleotides. The mobility shift assays were carried out in polyacrylamide gels stained with SYBR-Gold. One assay required 50-200 ng of PCR product and 1-3 microg of Thermus thermophilus his6-MutS protein. The advantages of this approach are: the small amounts of DNA required for the examination, simple and fast staining, no demand for PCR product purification, no labelling and radioisotopes required. The method was tested in the detection of cancer predisposing mutations in RET, hMSH2, hMLH1, BRCA1, BRCA2 and NBS1 genes. The approach appears to be promising in screening for unknown point mutations.