Dorota Nowakowska

Increased cancer risk of heterozygotes with NBS1 germline mutations in Poland

It has been suggested based on familial data that Nijmegen breakage syndrome (NBS) heterozygotes have an increased risk of malignant tumors. We found 15 carriers of the 657del5 mutation and 8 carriers of the R215W molecular variant of the NBS1 gene among 1,289 consecutive patients from Central Poland with various cancers and only 10 and 4 such carriers, respectively, in 1,620 controls from this region. Most of the 657del5 mutation carriers were found among patients with melanoma (4/105), non‐Hodgkin lymphoma (2/42) and breast cancer (4/224) and of the 234 patients with colorectal carcinoma 3 carried the 657del5 mutation and 3 others the R215W molecular variant. The frequencies of 657del5 mutation carriers among patients with melanoma and non‐Hodgkin lymphoma and of R215W carriers in patients with colorectal cancer were significantly higher than in controls (p < 0.01, < 0.05 and < 0.05 respectively). The pooled frequencies of 657del5 and R215W mutations in all cancer patients were also significantly higher than in controls (p < 0.05). Two carriers of the 657del5 mutation had second primary tumors. Malignant tumors among parents and siblings of 657del5 mutation carriers (14/77) were twice more frequent than in population controls. Three carriers of this mutation (2 probands with melanoma) reported melanoma in relatives. These results suggest strongly that NBS1 heterozygosity may be associated with elevated risk of some cancers. Larger studies are needed to evaluate the impact of the high frequency of germline NBS1 mutations on the cancer burden in the Slav populations.

Germline mutations 657del5 of the NBS1 gene contribute significantly to the incidence of breast cancer in Central Poland

Recent studies have demonstrated that heterozygous carriers of the NBS1 657del5 mutation have an increased risk for familial and bilateral breast cancer, but similar studies in consecutive breast cancer patients were inconclusive. Here, in a study of 562 nonselected breast cancer patients from Central Poland, we found 11 (1.96%) 657del5 mutation carriers vs. 3.47 expected (OR 3.21, 95%CI: 1.36–7.61, p = 0.0107) and only 9 (1.6%) carriers of the 5382insC mutation of the BRCA1 gene, most frequently found among breast cancer patients in Poland. No carriers of R215W, another pathogenic mutation of the NBS1 gene, were found in the present study. All carriers of the 657del5 mutation had sporadic breast tumors while 5 of 9 5382insC carriers had a family history of breast/ovarian cancer or bilateral breast carcinoma. In the pooled group of patients from the present and our previous study, carried out also in patients from Central Poland, we obtained the following risk estimates (OR) for 657del5 carriers, as related to the age at breast cancer diagnosis: <40 years: 8.36; (95%CI: 2.57–27.27) p = 0.0003; <50 years: 4.27 (95%CI: 1.67–10.89) p = 0.003; ≥50 years: 2.40 (95%CI: 0.91–6.35) p = 0.1250; all ages: 3.13 (95% CI: 1.40–7.00) p = 0.0066. These findings demonstrate conclusively that NBS1 657del5 mutation carriers have a significantly, though moderately increased, age‐related risk of breast cancer, and imply that in populations with a high 657del5 carrier frequency this mutation may contribute substantially to the overall incidence of breast cancer, particularly in younger age groups.

A novel germline PALB2 deletion in Polish breast and ovarian cancer patients

BackgroundPALB2 protein was recently identified as a partner of BRCA1 and BRCA2 which determines their proper function in DNA repair.MethodsInitially, the entire coding sequence of the PALB2 gene with exon/intron boundaries was evaluated by the PCR-SSCP and direct sequencing methods on 70 ovarian carcinomas. Sequence variants of interest were further studied on enlarged groups of ovarian carcinomas (total 339 non-consecutive ovarian carcinomas), blood samples from 334 consecutive sporadic and 648 consecutive familial breast cancer patients, and 1310 healthy controls from central Poland.ResultsTen types of sequence variants were detected, and among them four novel polymorphisms: c.2996+58T>C in intron 9; c.505C>A (p.L169I), c.618T>G (p.L206L), both in exon 4; and c.2135C>T (A712V) in exon 5 of the PALB2 gene. Another two polymorphisms, c.212-58A>C and c.2014G>C (E672Q) were always detected together, both in cancer (7.5% of patients) and control samples (4.9% of controls, p = 0.2). A novel germline truncating mutation, c.509_510delGA (p.R170fs) was found in exon 4: in 2 of 339 (0.6%) unrelated ovarian cancer patients, in 4 of 648 (0.6%) unrelated familial breast cancer patients, and in 1 of 1310 controls (0.08%, p = 0.1, p = 0.044, respectively). One ovarian cancer patient with the PALB2 mutation had also a germline nonsense mutation of the BRCA2 gene.ConclusionsThe c.509_510delGA is a novel PALB2 mutation that increases the risk of familial breast cancer. Occurrence of the same PALB2 alteration in seven unrelated women suggests that c.509_510delGA (p.R170fs) is a recurrent mutation for Polish population.

Prevalence of the most frequent BRCA1 mutations in Polish population

The purpose of our study was to establish the frequency and distribution of the four most common BRCA1 mutations in Polish general population and in a series of breast cancer patients. Analysis of the population frequency of 5382insC (c.5266dupC), 300T >G (p.181T >G), 185delAG (c.68_69delAG) and 3819del5 (c.3700_3704del5) mutations of the BRCA1 gene were performed on a group of respectively 16,849, 13,462, 12,485 and 3923 anonymous samples collected at birth in seven Polish provinces. The patient group consisted of 1845 consecutive female breast cancer cases. The most frequent BRCA1 mutation in the general population was 5382insC found in 29 out of 16,849 samples (0.17%). 300T >G and 3819del5 mutations were found in respectively 11 of 13,462 (0.08%) and four of 3923 (0.1%) samples. The population prevalence for combined Polish founder 5382insC and 300T >G mutations was 0.25% (1/400). The frequencies of 5382insC and 300T >G carriers among consecutive breast cancer cases were, respectively, 1.9% (35/1845) and 1.2% (18/1486). Comparing these data with the population frequency, we calculated the relative risk of breast cancer for 5382insC mutation at OR = 17 and for 300T >G mutation at OR = 26. Our results, based on large population studies, show high frequencies of founder 5382insC and 300T >G BRCA1 mutations in Polish general population. Carriage of one of these mutations is connected with a very high relative risk of breast cancer.

Novel germline mutations in the adenomatous polyposis coli gene in Polish families with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is a genetically determined disorder that is inherited in an autosomal dominant manner. The occurrence of FAP is associated with mutations in the APC gene, which were described in 1991.1 De novo mutations of the APC gene occur in one per 10 000 newborns. The APC gene is localised on chromosome 5q21 and consists of 21 exons. In most cases, mutations of the APC gene are small deletions or insertions: the AAAGA deletion at codon 1309, which occurs in 10% of families with FAP, and the ACAAA deletion at codon 1061, which occurs in 5% of families with FAP, are the most frequent mutations. Ninety-two percent of all mutations in the APC gene lead to truncations of the APC protein product. Dysfunction of the APC gene causes the accumulation of B-cathenin and the expression of genes that promote cell division. The FAP syndrome contributes only a relatively low percentage of all colorectal carcinomas (1–2%) and is characterised by the presence of numerous (at least 100) polyps that line the mucosa of the large intestine and rectum. The occurrence of other gastrointestinal adenomas, cutaneous sebaceous cysts, osteomas (mostly in the jaw, scapula, and long bones), connective tissue neoplasms, desmoid tumours, and, in some cases, coexisting duodenal and thyroid carcinomas (which together are classified as Gardner syndrome) and less common structural deformations in the teeth may also be observed.2,3 The DNA bank of Polish families with FAP was established in 1997 at the Institute of Human Genetics, Polish Academy of Science in Poznan. This study reports a spectrum of mutations of the APC gene in Polish patients with FAP. ### Patients Clinical diagnoses of FAP in patients were established in genetic centres or gastroenterology clinics in Poznan, Szczecin, Krakow, Wroclaw, Gdansk, Warszawa, and Lodź, appropriate to the …

Limited significance of family history for presence of BRCA1 gene mutation in Polish breast and ovarian cancer cases

It is estimated that about 5–10% of ovarian and 2–5% of all breast cancer patients are carriers of a germline BRCA1 or BRCA2 gene mutation. Most families with detected BRCA1 or BRCA2 gene mutation are qualified for molecular testing on the basis of family history of breast or ovarian cancers. The purpose of our study was to establish the frequency of positive family history of cancer in a series of Polish consecutive breast and ovarian cancer patients in two groups, with and without the BRCA1 gene mutations. We analysed the prevalence of four of the most common BRCA1 mutations: 5382insC (c.5266dupC), 300T>G (p.181T>G), 185delAG (c.68_69delAG) and 3819del5 (c.3700_3704del5). The patient group consisted of 1,845 consecutive female breast and 363 ovarian cancer cases. 19 out of 37 (51%) of BRCA1-positive ovarian cancer patients and 21 out of 55 (39%) BRCA1-positive breast cancer had negative family history of breast and/or ovarian cancer among first- and second-degree relatives. In ovarian cancer patients, negative family history was more frequent in those with 300T>G BRCA1 gene mutation than in 5382insC carriers. This finding indicates the necessity of searching for 300T>G mutation in families with a single diagnosis of ovarian cancer in family. The high frequency of mutations detected in breast cancer patients lacking obvious family history shows that breast cancer patients should be qualified for genetic testing on the basis of wide clinical and pathological criteria.

Common low-penetrance risk variants associated with breast cancer in Polish women

BackgroundBreast cancer is the most common type of cancer and the second leading cause of cancer-death among women in Poland. The known high-risk mutations account for 25% of familial aggregation cases and 5% of total breast cancer predisposition. Genome-wide association studies have identified a number of common low-penetrance genetic variants, but their contribution to disease risk differs between populations.MethodsTo verify selected associations with breast cancer susceptibility among Polish women, the replication study was performed, included 1424 women with breast cancer and 1788 healthy persons. Sixteen single-nucleotide polymorphisms (SNPs) were analyzed using TaqMan SNP Genotyping Assays. Allele frequency differences were tested using chi2-test implemented in PLINK v1.07 and Cochran-Armitage trend test was performed using R software.ResultsSignificant differences (Bonferroni corrected p-valuecor ≤ 0.0197) in the frequency of alleles distribution between all cancer and control subjects were observed for four (rs2736098, rs13281615, rs1219648, rs2981582) out of 16 SNPs. The same result was obtained for group of patients without high-risk BRCA1/2 mutations. The rs1219648 (p-valuecor ≤ 6.73E-03) and rs2981582 (p-valuecor ≤ 6.48E-03) SNPs showed significant association with both familial and sporadic cancers. Additionally, rs2736098 (p-valuecor ≤ 0.0234) was associated with only sporadic cancers; also in group without carriers of high-risk mutation. All these associations revealed their significance also in Cochran-Armitage trend test. Opposite to other SNPs, rs2736098 was associated with a decreased risk of breast cancer.ConclusionThe association of four known susceptibility SNPs, representing three individual loci, with breast cancer risk in Polish women was confirmed. One of them (rs2736098) seems to be specific for the Polish population. Due to the population differences in allele frequencies, identification of general genetic risk factors requires sets of association studies conducted on different populations.

High Resolution Melting analysis as a rapid and efficient method of screening for small mutations in the STK11 gene in patients with Peutz-Jeghers syndrome

BackgroundPeutz-Jeghers syndrome (PJS) is a rare hereditary syndrome characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract, mucocutaneous pigmentation and increased risk of cancer in multiple internal organs. Depending on the studied population, its incidence has been estimated to range from 1:200 000 even up to 1:50 000 births. Being an autosomal disease, PJS is caused in most cases by mutations in the STK11 gene.MethodsThe majority of causative DNA changes identified in patients with PJS are small mutations and, therefore, developing a method of their detection is a key aspect in the advancement of genetic diagnostics of PJS patients. We designed 13 pairs of primers, which amplify at the same temperature and enable examination of all coding exons of the STK11 gene by the HRM analysis.ResultsIn our group of 41 families with PJS small mutations of the STK11 gene were detected in 22 families (54%). In the remaining cases all of the coding exons were sequenced. However, this has not allowed to detect any additional mutations.ConclusionsThe developed methodology is a rapid and cost-effective screening tool for small mutations in PJS patients and makes it possible to detect all the STK11 gene sequence changes occurring in this group.

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.

First Polish Cowden syndrome patient with confirmed PTEN gene mutation

Cowden syndrome is a rare hereditary disease. Incidence of the disease is conditioned by occurrence of mutations in the PTEN gene. The disease has a frequency of 1/120,000 newborn and it predisposes to the occurrence of hamartoma polyps in the gastrointestinal tract, skin tumours, as well as tumours of the breast, ovary and thyroid. Here we describe the case of a Polish patient diagnosed with Cowden syndrome with an identified mutation in the PTEN gene. The disease course of the patient is described and discussed along with other cases of carriers of substitution 68T>A in the PTEN gene.