[Show abstract][Hide abstract] ABSTRACT: Hereditary breast-ovarian cancer syndrome contributes to as much as 5-7% of breast cancer (BC) and 10-15% of ovarian cancer (OC) incidence. Mutations in the "canonical" genesBRCA1andBRCA2occur in 20-30% of affected pedigrees. In addition toBRCA1andBRCA2 mutations, germ-line lesions in theCHEK2,NBS1, andPALB2genes also contribute to familial BC clustering. The epidemiology of hereditary breast-ovarian cancer in Russia has some specific features. The impact of the "founder" effect is surprisingly remarkable: a single mutation,BRCA15382insC, accounts for the vast majority ofBRCA1defects across the country. In addition, there are two other recurrentBRCA1alleles:BRCA14153delA andBRCA1185delAG. BesidesBRCA1, in Russia breast cancer is often caused by germ-line alterations in theCHEK2andNBS1genes. In contrast toBRCA1andBRCA2, theCHEK2andNBS1heterozygosity does not significantly increase the OC risk. Several Russian breast cancer clinics recently started to investigate the efficacy of cisplatin in the therapy ofBRCA1-related cancers; initial results show a unique sensitivity ofBRCA1-associated tumours to this compound.
[Show abstract][Hide abstract] ABSTRACT: A significant portion of ovarian cancer (OC) cases is caused by germ-line mutations in BRCA1 or BRCA2 genes. BRCA testing is cheap in populations with founder effect and therefore recommended for all patients with OC diagnosis. Recurrent mutations constitute the vast majority of BRCA defects in Russia, however their impact in OC morbidity has not been yet systematically studied. Furthermore, Russian population is characterized by a relatively high frequency of CHEK2 and NBS1 (NBN) heterozygotes, but it remains unclear whether these two genes contribute to the OC risk.
The study included 354 OC patients from 2 distinct, geographically remote regions (290 from North-Western Russia (St.-Petersburg) and 64 from the south of the country (Krasnodar)). DNA samples were tested by allele-specific PCR for the presence of 8 founder mutations (BRCA1 5382insC, BRCA1 4153delA, BRCA1 185delAG, BRCA1 300T>G, BRCA2 6174delT, CHEK2 1100delC, CHEK2 IVS2+1G>A, NBS1 657del5). In addition, literature data on the occurrence of BRCA1, BRCA2, CHEK2 and NBS1 mutations in non-selected ovarian cancer patients were reviewed.
BRCA1 5382insC allele was detected in 28/290 (9.7%) OC cases from the North-West and 11/64 (17.2%) OC patients from the South of Russia. In addition, 4 BRCA1 185delAG, 2 BRCA1 4153delA, 1 BRCA2 6174delT, 2 CHEK2 1100delC and 1 NBS1 657del5 mutation were detected. 1 patient from Krasnodar was heterozygous for both BRCA1 5382insC and NBS1 657del5 variants.
Founder BRCA1 mutations, especially BRCA1 5382insC variant, are responsible for substantial share of OC morbidity in Russia, therefore DNA testing has to be considered for every OC patient of Russian origin. Taken together with literature data, this study does not support the contribution of CHEK2 in OC risk, while the role of NBS1 heterozygosity may require further clarification.
Full-text · Article · Feb 2009 · Hereditary Cancer in Clinical Practice
[Show abstract][Hide abstract] ABSTRACT: BRCA1 and BRCA2 germ-line mutations occur in a significant number of unselected ovarian cancer (OC) patients, thus making a noticeable contribution to OC morbidity. It is of interest whether CHEK2, which is frequently regarded as a third breast cancer specific gene, is also relevant to ovarian cancer pathogenesis. In this report we analyzed the presence of CHEK2 1100 delC founder mutation in 268 randomly recruited OC patients. The mutation was identified in 2 women with OC (0.8%) as compared to 1/448 (0.2%) healthy middle-aged and 0/373 elderly tumour-free women. Taken together this result and the negative findings of two other published reports on an association of CHEK2 with ovarian cancer indicate that there is no justification for intensive ovarian cancer screening in CHEK2 1100 delC carriers.
Full-text · Article · Feb 2007 · Hereditary Cancer in Clinical Practice
[Show abstract][Hide abstract] ABSTRACT: Three founder alleles of the CHEK2 gene have been associated with predisposition to a range of cancer types in Poland. Two founder alleles (1100delC and IVS2 + 1G >A) result in a truncated CHEK2 protein and the other is a missense substitution, leading to the replacement of a threonine with an isoleucine (I157T).
To establish if these variants play a role in the etiology of ovarian tumors, we genotyped 1108 Polish women with various types of ovarian tumors and 4000 controls for the three CHEK2 variants. We included 539 Polish women with benign ovarian cystadenomas, 122 women with borderline ovarian malignancies and 447 women with invasive ovarian cancer.
Positive associations were seen with the CHEK2 I157T missense variant and ovarian cystadenomas (OR = 1.7; P = 0.005), with borderline ovarian cancers (OR = 2.6; P = 0.002) and with low-grade invasive cancers (OR = 2.1; P = 0.04). There was no association with ovarian cancer of high grade (OR = 1.0). The association between the I157T missense variant was then confirmed in a second sample of Russian patients with borderline ovarian cancers (OR = 2.7; P = 0.06).
These data indicate that CHEK2 variants may predispose to a range of ovarian tumor types of low malignant potential, but not to aggressive cancers.
No preview · Article · Oct 2006 · Gynecologic Oncology
[Show abstract][Hide abstract] ABSTRACT: The BRCA1 4153delA allele is frequently referred to as the Russian founder mutation, as it was initially detected in several cancer families from Moscow. Our earlier studies have demonstrated 1% occurrence of BRCA1 4153delA heterozygosity in familial and/or early-onset and/or bilateral Russian breast cancer (BC) patients. Since literature data suggest that the 4153delA variant is more associated with ovarian cancer (OC) than with BC, we expected to reveal a highly elevated frequency of this genotype in Russian ovarian cancer series. However, real-time allele-specific PCR genotyping has detected only two BRCA1 4153delA carriers out of 177 unselected OC patients (1.1%). Both these carriers were early-onset and had serous carcinomas of grade 3. Thus, our study supports neither the Russian origin of BRCA1 4153delA mutation, nor its selectivity towards ovarian versus breast cancer predisposition.
Preview · Article · Sep 2006 · Hereditary Cancer in Clinical Practice