High rate of mutations in the BRCA1, BRCA2, CHEK2, NBN, and BLM genes in Russian ovarian cancer patients

Background. The early diagnosis of ovarian cancer (OC) is an important problem in modern gynecological oncology due to significant detection rates for late-stage tumors. Intensive screening of patients from high-risk groups that include OC predisposition gene mutation carriers is indicated.

Subjects and methods. An unselected group of 202 patients with OC and two control groups of blood donors: 591 healthy females; 1197 persons (including 591 females, 606 males) were examined. Patients and healthy individuals who identified themselves as ethnic Russians and residents of the Russian Federation participated in the study. Whole peripheral blood samples were collected at the Clinical Subdivisions of the N.N. Blokhin Russian Cancer Research Center and at the Department of Transfusiology of the Acad. B.V. Petrovsky Russian Research Center of Surgery in 2012–2013. Informed consent was obtained from all the participants. DNA was extracted using a Prep-GS-Genetics reagent kit. Real-time polymerase chain reaction genotyping assay was carried out by melting-curve analysis employing an BRCA SNP genotyping kit
(BRCA1 and BRCA2 gene mutations) and original oligonucleotides (CHEK2, NBN, and BLM gene mutations). Thirteen population-specific mutations, including 7 (185delAG, 4153delA, 5382insC, 3819delGTAAA, 3875delGTCT, 300T>G, and 2080delA) in the BRCA1 gene, 1 (6174delT) in the BRCA2 gene, 3 (1100delC, IVS2+1G>A, and 470T>C) in the CHEK2 gene, 1 (657delACAAA) in the NBN gene, and 1 (1642C>T) in the BLM gene, were genotyped. Polymerase chain reaction was performed using a DTprime real-time detection thermal cycler.

Results and discussion. BRCA1 and BRCA2 gene mutations were detected in 46 (22.8 %) patients with OC; the prevailing mutation in the BRCA1 gene was 5382insC (58.7 %). OC was diagnosed in 32.6 % of the patients aged 51 years or older. The rate of moderate-penetrance mutations (1100delC and IVS2+1G>A in the CHEK2 gene, 657del5 in the NBN gene, and 1642C>T in the BLM gene) was 0.5–1.0 % in the group of OC patients and 0–0.3 % in the control group of healthy women. The majority of these patients (5/6) were diagnosed with OC at age less than 50 years. The CHEK2 mutation, 470T>C, was more frequently encountered in the control group (6.6 %) than in the OC patient group (5.0 %). High rate of the CHEK2 mutation, IVS2+1G>A, was first shown for OC patients in the Russian Federation, the odds ratio was 11.9 (95 % confidence interval, 9.5–14.3; p = 0.056). It was preliminarily concluded that it played an important role in the development of OC in the Russian population; our findings should be verified in further investigations. The difference in the rate of mutations, such as 1100delC, IVS2+1G>A and 470T>C in the CHEK2 gene, 657del5 in the NBN gene, 1642C>T in the BLM gene, were insignificant in the patient and control groups, which may be related to the low population rate of these genetic markers and, in case of the CHEK2 mutation, 470T>C, may be linked to its low penetrance. By taking into account the fact that numerous studies have proven the clinical significance of all examined moderate-penetrance mutations whose prevalence in the Russian population has been confirmed by the authors of this paper, the inclusion of the mutations in a diagnostic panel to detect hereditary predisposition to OC is substantiated. The associated risks are higher for the rare mutations leading to the formation of truncated nonfunctional proteins, which are 1100delC and IVS2+1G>A in the CHEK2 gene, 657del5 in the NBN gene, and 1642C>T in the BLM gene. The penetrance of the CHEK2 mutation, 470T>C, is lower, which should be kept in mind during medical genetic counselling.

Conclusion. The total rate of mutations in the BRCA1, BRCA2, CHEK2, NBN, and BLM genes in patients with OC was 30.7 %, which determines the expediency of molecular genetic screening in this category of patients.

1. Злокачественные новообразования в России в 2012 году (заболеваемость и смертность). Под ред. А.Д. Каприна, В.В. Старинского, Г.В. Петровой. М.: ФГБУ «МНИОИ им. П.А. Герцена» Минздрава России, 2014. 250 с.

2. Давыдов М.И., Аксель Е.М. Статистика злокачественных новообразований в России и странах СНГ в 2009 году. Вестн РОНЦ им. Н.Н. Блохина РАМН 2011; 22(3 прил. 1).

3. Partridge E., Kreimer A.R., Greenlee R.T. et al.; PLCO Project Team. Results from four rounds of ovarian cancer screening in a randomized trial. Obstet Gynecol 2009;113(4):775–82.

4. Domchek S.M., Friebel T.M., Singer C.F. et al. Association of risk-reducing surgery in BRCA1 or BRCA2 mutation carriers with cancer risk and mortality. JAMA 2010;304(9):967–75.

5. Long K.C., Kauff N.D. Hereditary ovarian cancer: recent molecular insights and their impact on screening strategies. Curr Opin Oncol 2011;23(5):526–30.

6. Любченко Л.Н. Наследственный рак молочной железы и/или яичников: ДНК-диагностика, индивидуальный прогноз, лечение и профилактика. Дис. ... д-ра мед. наук. М., 2009.

7. Lalwani N., Prasad S.R., Vikram R. et al. Histologic, molecular, and cytogenetic features of ovarian cancers: implications for diagnosis and treatment. Radiographics 2011;31(3): 625–46.

8. Zhang S., Royer R., Li S. et al. Frequencies of BRCA1 and BRCA2 mutations among 1,342 unselected patients with invasive ovarian cancer. Gynecol Oncol 2011;121(2): 353–7.

9. Chen S., Parmigiani G. Meta-analysis of BRCA1 and BRCA2 penetrance. J Clin Oncol 2007;25(11):1329–33.

10. Antoniou A., Pharoah P.D., Narod S. et al. Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case Series unselected for family history: a combined analysis of 22 studies. Am J Hum Genet 2003;72(5):1117–30.

11. Cybulski C. Selected aspects of inherited susceptibility to prostate cancer and tumours of different site of origin. Hered Cancer Clin Pract 2007;5(3):164–79.

12. Apostolou P., Fostira F. Hereditary breast cancer: the era of new susceptibility genes. Biomed Res Int 2013;2013:747318.

13. Walsh T., Casadei S., Lee M.K. et al. Mutations in 12 genes for inherited ovarian, fallopian tube, and peritoneal carcinoma dentified by massively parallel sequencing. Proc Natl Acad Sci USA 2011;108(44):18032–7.

14. Cast ra L., Krieger S., Rousselin A. et al. Next-generation sequencing for the diagnosis of hereditary breast and ovarian cancer using genomic capture targeting multiple candidate genes. Eur J Hum Genet 2014;22(11): 1305–13.

15. Ferla R., Cal V., Cascio S. et al. Founder mutations in BRCA1 and BRCA2 genes. Ann Oncol 2007;18 Suppl 6:vi93–8.

16. Prokofyeva D., Bogdanova N., Dubrowinskaja N. et al. Nonsense mutation p.Q548X in BLM, the gene mutated in Bloom's syndrome, is associated with breast cancer in Slavic populations. Breast Cancer Res Treat 2013;137(2):533–9.

17. Sokolenko A.P., Iyevleva A.G., Preobrazhenskaya E.V. et al. High prevalence and breast cancer predisposing role of the BLM c.1642 C > T (Q548X) mutation in Russia. Int J Cancer 2012;130(12):2867–73.

18. Steffen J., Nowakowska D., Niwińska A. et al. Germline mutations 657del5 of the NBS1 gene contribute significantly to the incidence of breast cancer in Central Poland. Int J Cancer 2006;15(2):472–5.

19. Weischer M., Bojesen S.E., Ellervik C. et al. CHEK2*1100delC genotyping for clinical assessment of breast cancer risk: meta-analyses of 26,000 patient cases and 27,000 controls. J Clin Oncol 2008;26(4):542–8.

20. Han F.F., Guo C.L., Liu L.H. The effect of CHEK2 variant I157T on cancer susceptibility: evidence from a meta-analysis. DNA Cell Biol 2013;32(6):329–35.

21. Батенева Е.И., Мещеряков А.А., Любченко Л.Н. и др. Частота одиннадцати мутаций генов BRCA1 и BRCA2 в неотобранной выборке больных раком молочной железы россиянок. Уральск мед журн 2011;3(81):69–73.

22. Кофиади И.А., Ребриков Д.В. Методы детекции однонуклеотидных полиморфизмов: аллель-специфичная ПЦР и гибридизация с олигонуклеотидной пробой. Генетика 2006;42(1):22–32.

23. Часовникова О.Б., Митрофанов Д.В., Демченко Д.О. и др. BRCA1 и BRCA2 мутации у больных раком молочной железы в сибирском регионе. Сиб онкол журн 2010;(5):32–5.

24. Iyevleva A.G., Suspitsin E.N., Kroeze K. et al. Non-founder BRCA1 mutations in Russian breast cancer patients. Cancer Lett 2010;298:258–63.

25. Suspitsin E.N., Sherina N.Y., Ponomariova D.N. et al. High frequency of BRCA1, but not CHEK2 or NBS1 (NBN), founder mutations in Russian ovarian cancer patients Hered Cancer Clin Pract 2009;25(7):5.