Three novel BRCA1/BRCA2 mutations in breast/ovarian cancer families in Croatia.

BRCA1 and BRCA2 genes from 167 candidates (145 families) were scanned for mutations. We identified 14 pathogenic point mutations in 17 candidates, 9 in BRCA1 and 5 in BRCA2. Of those, 11 have been previously described and 3 were novel (c.5335C>T in BRCA1 and c.4139_4140dupTT and c.8175G>A in BRCA2). No large deletions or duplications involving BRCA1 and BRCA2 genes were identified. No founder mutations were detected for the Croatian population. Croatia shares most of the mutations with neighboring Slovenia and also with Germany, Austria and Poland. Two common sequence variants in BRCA1, c.2077G>A and c.4956G>A, were found more frequently in mutation carriers compared to healthy controls. No difference in BRCA2 variants was detected between the groups. Haplotype inference showed no difference in haplotype distributions between deleterious mutation carriers and non-carriers in neither BRCA1 nor BRCA2. In silico analyses identified one BRCA1 sequence variant (c.4039A>G) and two BRCA2 variants (c.5986G>A and c.6884G>C) as harmful with high probability, and inconclusive results were obtained for our novel BRCA2 variant c.3864_3866delTAA. Combination of QMPSF and HRMA methods provides high detection rate and complete coverage of BRCA1/2 genes. Benefit of BRCA1/2 mutation testing is clear, since we detected mutations in young unaffected women, who will be closely monitored for breast and ovarian cancer.

[Molecular basis of breast cancer related to BRCA 1 and BRCA2 genes: characteristics and targeting therapy]. / Molekularna osnova raka dojke vezana uz gene BRCA1 i BRCA2: karakteristike i ciljana terapija.

Breast cancer is one of the most frequent tumors in women, and BRCA1 and BRCA2 genes play a major role in the hereditary susceptibility for this disease. Until the age of 70 women carrying a mutation in BRCA1 or BRCA2 gene have a 45-85% probability of developing breast cancer, and 11-62% probability of developing ovarian cancer. Mutation carrier's tumors contain nonfunctional BRCA1 or BRCA2 genes, which in healthy cells are involved in DNA repair. These tumors show an increased sensitivity to DNA damaging chemical agents and to PARP (poly(adenosine diphosphate-ribose) polymerase1) inhibitors. New targeted therapies already in use are directed toward tumors of mutation carriers. Successful treatment is most likely to be achieved through cooperation of a pathologist, oncologist and a genetic laboratory performing BRCA genes mutation screening.

New sequence variants in BRCA1 and BRCA2 genes detected by high-resolution melting analysis in an elderly healthy female population in Croatia.

BACKGROUND: Mutations in BRCA1 and BRCA2 genes are associated with family predisposition to breast and ovarian cancer. Novel screening methods are required for efficient and rapid detection of sequence variants in cancer patients and their family members. METHODS: The screening for variants in the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2 in Croatia was performed by a high-resolution melting approach, which is based on differences in melting curves caused by variations in nucleotide sequence. This is the first screening in Croatia on elderly healthy women with no family history of cancer. BRCA1 screening was performed on 220 and BRCA2 screening on 115 samples. RESULTS: In a population well beyond the average age of breast/ovarian cancer onset, 21 different sequence variants in the BRCA1 gene (one novel: c.5193+49_50delTA) and 36 variants in the BRCA2 gene (7 novel: c.459A>C, c.3318C>A, c.4412_ 4414delGAA, c.4790C>A, c.6264T>C, c.9087G>A, and c.9864A>G) were detected. CONCLUSIONS: Nine BRCA1 and seven BRCA2 known variants appeared with such high frequencies that they could be declared as harmless in this population. Eight BRCA1 high frequency variants, located further from the promoter region, appear to be strongly correlated. Three novel variants that changed the amino acid sequence of the BRCA2 protein (two missense base substitutions, c.3318C>A and c.4790C>A, and one codon deletion c.4412_4414delGAA), appearing only once, were predicted to have no potential effect on protein structure and function.