Biomedical subjects

B A Agnarsson

Publications and source records attributed to B A Agnarsson.

At least 19 recordsLinked to original sources

PubMed2006

Nordic collaborative study of the BARD1 Cys557Ser allele in 3956 patients with cancer: enrichment in familial BRCA1/BRCA2 mutation-negative breast cancer but not in other malignancies.

BACKGROUND: BARD1 was originally identified as a BRCA1-interacting protein but has also been described in tumour-suppressive functions independent of BRCA1. Several studies have indicated that the BARD1 gene is a potential target for germline changes predisposing to breast and ovarian cancer. The C-terminal Cys557Ser change has previously been uncovered to associate with an increased risk of breast cancer and was recently shown to result in defective apoptotic activities. AIM AND METHODS: Conformation-sensitive gel electrophoresis, minisequencing, TaqMan assays, denaturing high-performance liquid chromatography analysis and DNA sequencing were used to investigate the prevalence of the Cys557Ser allele in a large Nordic case-control study cohort consisting of 2906 patients with breast or ovarian cancer, 734 with prostate cancer, 188 with colorectal cancer, 128 men with breast cancer, and 3591 controls from Finland, Iceland, Denmark, Sweden and Norway. RESULTS: The frequency of the BARD1 Cys557Ser variant seemed to increase among patients from families with breast or ovarian cancer lacking BRCA1 or BRCA2 mutations: a significant difference was obtained compared with controls (6.8% v 2.7%; p<0.001; odds ratio (OR) 2.6; 95% confidence interval (CI) 1.7 to 4.0) and with patients from BRCA1/BRCA2 mutation-positive families (6.8% v 2.2%; p = 0.01; OR 3.2; 95% CI 1.2 to 8.3). In contrast, no major association with male breast, ovarian, colorectal or prostate cancer was observed. Additionally, a novel BARD1 allele resulting in Ser558Pro was identified in familial breast cancer cases. CONCLUSION: These results provide further evidence that BARD1 Cys557Ser confers a slightly increased risk of breast cancer in women.

Adolescent↗

PubMed2001

Alterations of the FHIT gene in breast cancer: association with tumor progression and patient survival.

Our previous results on breast tumors show that LOH (loss of heterozygosity) at the FHIT locus is associated with reduced Fhit protein expression. We have also shown that LOH at this locus is significantly higher in tumors from patients carrying the BRCA2 999de15 mutation than in tumors without this mutation, presumably because of lack of DNA repair. Here, our aim was to determine the relationship of FHIT LOH with breast tumor progression. Five microsatellite markers located within the FHIT gene were typed in 239 breast tumors and corresponding normal tissue, and the LOH results were compared with clinicopathologic factors and LOH at other chromosome regions. LOH at FHIT is associated with estrogen- and progesterone-negative breast tumors, high S-phase fraction, reduced patient survival, and LOH at chromosome regions 6q, 7q, 8p, 9p, 11p, 11q, 13q, 16q, 17p, 17q, 18q, and 20q. A multivariate analysis shows that LOH at FHIT results in a 60% increased relative risk of dying. We conclude that the loss of FHIT results in growth advantage of breast tumor cells, is associated with unstable genome, and may be of prognostic value.

Acid Anhydride Hydrolases↗

PubMed2000

Analysis of HPC1, HPCX, and PCaP in Icelandic hereditary prostate cancer.

Putative prostate cancer susceptibility loci have recently been identified by genetic linkage analysis on chromosomes 1q24-25 (HPC1). 1q44.243 (PCaP), and Xq27-28 (HPCX). In order to estimate the genetic linkage in Icelandic prostate cancer families, we genotyped 241 samples from 87 families with eleven markers in the HPC1 region, six markers at PCaP, and eight at HPCX. Concurrently, we assessed allelic imbalance at the HPC1 and PCaP loci in selected tumors from the patients. For each of the candidate regions, the combined parametric and non-parametric LOD scores were strongly negative. Evidence for linkage allowing for genetic heterogeneity was also insignificant for all the regions. The results were negative irrespective of whether calculations were performed for the whole material or for a selected set of early age at onset families. The prevalence of allelic imbalance was relatively low in both the HPC1 (0%-9%) and PCaP (5%-20%) regions and was not elevated in tumors from positively linked families. Our studies indicate that the putative cancer susceptibility genes at chromosomes 1q24-25, 1q44.2-43, and Xq27-28 are unlikely to contribute significantly to hereditary prostate cancer in Iceland and that selective loss of the HPC1 and PCaP loci is a relatively rare somatic event in prostate cancers.

Alleles↗

PubMed2000

Analysis of the fragile histidine triad (FHIT) gene in lobular breast cancer.

The fragile histidine triad (FHIT) gene is a candidate tumour suppressor gene in breast and other cancers. We investigated deletions within the FHIT gene in lobular breast cancer and found that 16% of cases showed loss of heterozygosity (LOH) within the gene. We compared LOH within FHIT in lobular and ductal breast tumours and found a significant association between LOH at FHIT and the ductal histological type (P<0.001). To determine whether genomic alteration of the FHIT gene in lobular breast cancer leads to Fhit inactivation we have assessed the level of Fhit expression by immunohistochemical detection and determined that 27% (15 of 55) consecutive sporadic lobular tumours showed negative or reduced Fhit expression. A significant association was found between LOH at the FHIT gene and reduced Fhit expression in lobular and ductal tumours (P=0.025 and P=0.001, respectively). Thus, genetic alterations within the FHIT gene, leading to loss of Fhit protein, may play an important role in the carcinogenesis of a significant number of sporadic lobular breast cancers, even though the apparent frequency of genomic alterations within the gene is lower than in ductal breast cancer.

Acid Anhydride Hydrolases↗

PubMed2000

Chromosome 8p alterations in sporadic and BRCA2 999del5 linked breast cancer.

Chromosomal losses involving the short arm of chromosome 8 are frequent in a variety of tumour types, including breast cancer, suggesting the presence of one or more tumour suppressor genes in this region. In this study, we have used 11 microsatellite markers to analyse loss of heterozygosity (LOH) at chromosome 8p in 151 sporadic breast tumours and 50 tumours from subjects carrying the BRCA2 999del5 mutation. Fifty percent of sporadic tumours compared to 78% of BRCA2 linked tumours exhibit LOH at one or more markers at 8p showing that chromosome 8p alterations in breast tumours from BRCA2 999del5 carriers are more pronounced than in sporadic breast tumours. The pattern of LOH is different in the two groups and a higher proportion of BRCA2 tumours have LOH in a large region of chromosome 8p. In the total patient material, LOH of 8p is associated with LOH at other chromosome regions, for example, 1p, 3p, 6q, 7q, 9p, 11p, 13q, 17p, and 20q, but no association is found between LOH at 8p and chromosome regions 11q, 16q, 17q, and 18q. Furthermore, an association is detected between LOH at 8p and positive node status, large tumour size, aneuploidy, and high S phase fraction. Breast cancer patients with LOH at chromosome 8p have a worse prognosis than patients without this defect. Multivariate analysis suggests that LOH at 8p is an independent prognostic factor. We conclude that chromosome 8p carries a tumour suppressor gene or genes, the loss of which results in growth advantage of breast tumour cells, especially in carriers of the BRCA2 999del5 mutation.

BRCA2 Protein↗

PubMed2000

[Liver metastases of unknown origin.].

OBJECTIVE: Approximately 5% of cancer patients are diagnosed with tumour of unknown origin (3-4% in Iceland). Of those 10-30% have liver metastases. Liver metastases of unknown origin is thus not an uncommon problem. In the present study information about the origin and histology of liver metastases of unknown origin was compiled. MATERIAL AND METHODS: Records of all biopsies from liver metastases performed in the years 1987-1996 were retrieved from the medical database of the Department of Pathology at the University of Iceland. The biopsies came from a group of 176 patients. Ninety-two cases, in which the origin of the primary tumour was suspected or known, were excluded from the study, leaving 84 cases where the primary was completely unknown. The database of the Icelandic Cancer Society was used to gather data about the final tissue diagnosis and the location of the primary tumour when known. RESULTS: The Cancer Society data revealed the location of the primary tumour in 55 of the 84 cases of liver metastases of unknown origin. The most prevalent (75%) primary tumours were cancers of the pancreas (15), lung (13) and colon/rectum (12). The tissue diagnosis was adenocarcinoma in 33 of the 55 cases. In the male patients 83% of the adenocarcinoma metastases came from the colon/rectum or pancreas. The corresponding figure for the female patients was 67%, while 20% of the tumours in females originated in the gallbladder and biliary tree. CONCLUSIONS: In two thirds of the cases of liver metastases of unknown origin the primary tumour was later discovered. The most prevalent tumours were cancers in the pancreas, lung and colon/rectum. Adenocarcinoma was the tissue diagnosis in 60% of cases.

English Abstract↗

PubMed1999

Reduced Fhit expression in sporadic and BRCA2-linked breast carcinomas.

Evidence for alteration of the FHIT gene in a significant fraction of breast carcinomas has been reported, in apparent concordance with loss of heterozygosity (LOH) at chromosome region 3p14.2 in breast cancer and benign proliferative breast disease. A significantly higher frequency of LOH at the FHIT locus was reported for BRCA2-/- tumors, possibly due to misrepaired double-strand breaks at this common fragile region. To determine whether such genomic alterations lead to Fhit inactivation, we have assessed the level of Fhit expression by immunohistochemical detection in sporadic tumors and cancers occurring in BRCA2 999del5 carriers. To determine whether Fhit inactivation may have prognostic significance, we have also assessed expression of breast cancer markers and clinical features in sporadic tumors relative to Fhit expression. Of 40 consecutive sporadic breast carcinomas studied for tumor markers, 50% showed reduced Fhit expression. In these sporadic cancers, loss of Fhit expression was not correlated significantly with the presence or absence of other tumor markers. In a study of 58 sporadic and 34 BRCA2 999del5 Icelandic invasive cancers, there was a significant association of LOH at 3p14.2 with reduced expression of Fhit (P = 0.001); also the lower expression of Fhit and higher LOH at 3p14.2 in BRCA2 999del5 tumors relative to sporadic cancers was significant (P = 0.002). Thus, genetic alteration at the fragile site within the FHIT gene leads to loss of Fhit protein in a significant fraction of sporadic breast cancers and a much larger fraction of familial breast cancers with an inherited BRCA2 mutation, consistent with the idea that loss of BRCA2 function affects stability of the FHIT/FRA3B locus.

Acid Anhydride Hydrolases↗

PubMed1999

Enhanced B cell survival in familial macroglobulinaemia is associated with increased expression of Bcl-2.

A family with three cases of macroglobulinaemia of undetermined significance (MGUS), and one case each of immunoblastic lymphoma, Waldentröm's macroglobulinaemia and multiple myeloma was first described 20 years ago. We have previously identified 10 out of 35 healthy family members tested whose lymphocytes produced abnormally high amounts of immunoglobulins in culture. In the present study lymphocyte subpopulations of these hyper-responders have been further characterized and lymphocyte reactivity and survival in vitro have been studied. No differences were detected in the proportions of resting B lymphocytes (CD19+) co-expressing CD5, CD10, CD11b, or CD38, and the CD4/CD8 ratio of T cells was normal before and after stimulation with pokeweed mitogen (PWM). The initial rate of response in terms of immunoglobulin production was not increased, but immunoglobulin levels continued to rise during the second week of culture whereas the production peaked at 8 days in control cultures. This was associated with significantly greater survival of lymphocytes and at 14 days surviving B cells could only be identified in samples from hyper-responders. A lymph node removed because of tuberculosis from a family member 23 years before the diagnosis of multiple myeloma showed very marked Bcl-2 expression in a B cell follicle. This was not seen in a tuberculous lymph node from an unrelated subject. Stimulated cultures from three hyper-responders tested demonstrated significantly higher retention of Bcl-2 in B cells compared with one family control and six unrelated controls. We conclude that the increased production of immunoglobulins previously observed in this family with an inherited tendency for benign and malignant B cell proliferation is the result of enhanced B cell survival, which is associated with increased expression of Bcl-2 following stimulation.

B-Lymphocyte Subsets↗

PubMed1998

High incidence of loss of heterozygosity in breast tumors from carriers of the BRCA2 999del5 mutation.

Germ-line mutation in the BRCA2 gene confers an increased risk of breast cancer. An elevation of additional genetic defects in tumors of patients with germ-line mutation in the BRCA2 gene compared with sporadic breast tumors has been reported. To evaluate the nature of the difference, we did detailed mapping of chromosomes 1p, 3p, 6q, 11, 13q, 16q, 17, and 20q, using microsatellite markers. We found that the frequency of loss of heterozygosity was similar at some chromosomal regions in the BRCA2 999del5 and sporadic tumors but significantly different at others. These others include chromosomal arms 3p, 6q, 11p, 11q, 13q, and 17p. Loss of heterozygosity mapping suggests that the same chromosome regions are involved in both tumor groups but at elevated frequencies in BRCA2 999del5 tumors. This higher frequency of genetic aberrations could pinpoint genes that selectively promote tumor progression in individuals predisposed to breast cancer due to the BRCA2 999del5 germ-line mutation. Accumulation of somatic genetic changes during tumor progression may follow a specific and more aggressive pathway of chromosome damage in these individuals.

BRCA2 Protein↗

PubMed1998

High incidence of loss of heterozygosity at chromosome 17p13 in breast tumours from BRCA2 mutation carriers.

Breast tumours from BRCA1 and BRCA2 mutation carriers are genetically instable and display specific patterns of chromosomal aberrations, suggestive of distinct genetic pathways in tumour progression. The frequency of abnormalities affecting chromosome 17p and the TP53 gene was determined in 27 breast tumours from 26 female patients carrying the Icelandic BRCA2 founder mutation (999del5). Loss of heterozygosity (LOH) was detected in 23 of the 27 tumours (85%). The majority of tumours manifesting LOH had lost a large region on 17p, although a more restricted loss, including the TP53 locus was seen in a few tumours. Positive p53 immunostaining was observed in 18 of 26 tumours (69%). However, mutations in the TP53 gene were detected in only three tumours (11%), including a missense (codon 139) and a nonsense mutation (codon 306) in two tumours with moderate p53 expression and a frameshift deletion (codon 182) in a tumour with no detectable p53 expression. Positive p53 immunostaining, mainly weak, was observed in 16 of the 24 tumours (66%) without TP53 mutation. The high frequency of LOH at chromosome 17p13 suggests that one or more genes from this region are involved in the development of BRCA2-induced breast cancer. The frequent finding of weak overexpression of, presumably wild type p53 protein, suggests an alternative mechanism of TP53 involvement specific to these tumours.

BRCA2 Protein↗

PubMed1998

Mapping loss of heterozygosity at chromosome 13q: loss at 13q12-q13 is associated with breast tumour progression and poor prognosis.

Several chromosome regions exhibit loss of heterozygosity (LOH) in human breast carcinoma and are thought to harbour tumour suppressor genes (TSG). At chromosome 13q, two TSGs have been identified, RB1 at 13q14 and BRCA2 at 13q12-q13. In this study, 139 sporadic breast tumours were analysed with 18 polymorphic microsatellite markers for detailed mapping of LOH at chromosome 13q and evaluation of an association with known progression factors. LOH with at least one marker was observed in 71 (51%) of the tumours analysed. The deletion mapping indicated three LOH target regions, 13q12-q13, 13q14 and 13q31-q34. LOH at chromosome 13q12-q13 was associated with low progesterone receptor content, a high S phase fraction and aneuploidy. Multivariate analysis adjusting for lymph node involvement and S phase fraction showed that patients with tumours exhibiting LOH at 13q12-q13 have a 3-4-fold increased risk of recurrence and death compared with other patients. Our results suggest there are at least three separate LOH target regions at chromosome 13q and inactivation of one or more genes at chromosome 13q12-q13 results in poor prognosis for breast cancer patients.

Aneuploidy↗

PubMed1998

Inherited BRCA2 mutation associated with high grade breast cancer.

Inheritance is believed to play a major role in 5-10% of breast cancer. The breast cancer susceptibility genes BRCA1 and BRCA2 are estimated to account for more than half of these cases. Recent studies have suggested that breast cancers associated with BRCA1 germline mutations are of higher grade than sporadic cases. The purpose of this investigation was to determine if there are significant pathologic and biologic differences between hereditary BRCA2 related breast carcinomas and non-hereditary breast cancers. Forty cases of hereditary breast cancer from families associated with a specific 999del5 BRCA2 mutation were compared with regard to histologic and biologic factors to an age matched control group. Thirty-four patients (85%) had ductal carcinoma, two had lobular carcinoma, and one patient had medullary carcinoma. Compared to the control group, the BRCA2 tumors had less tubule formation (p = 0.02), more nuclear pleomorphism (p = 0.02), and higher mitotic rates (p = 0.002), and were thus of higher histologic grade (p = 0.003). By flow cytometry the BRCA2 tumors also had significantly higher S-phase fractions than the control tumors (p = 0.02). Significant differences in axillary lymph-node involvement or ploidy status were not detected. According to the results of this study, hereditary breast cancers associated with the 999del5 BRCA2 mutation are high grade tumors with a rapid proliferation rate. Other or additional factors than the defining BRCA2 mutation are involved in determining the tumor type.

Adult↗

PubMed1998

Basal cell carcinoma of the eyelid. Risk of recurrence according to adequacy of surgical margins.

PURPOSE: To examine all basal cell carcinomas of the eyelid diagnosed in Iceland during a 25-year period, paying special attention to the surgical margins of excision in relation to recurrence. Based on the results a simple, clinically relevant method of classifying the surgical margin is proposed. METHODS: All histologically proven basal cell cancer specimens from eyelids were reviewed retrospectively. The surgical excision margins were classified as radical, marginal or intralesional. RESULTS: Recurrence risk was low when the tumor had a surgical margin described as radical or marginal. The recurrence rate was 38% when the margin was intralesional. CONCLUSION: By assessing the surgical margins by this method, which is easy to apply, better understanding between the pathologist and the surgeon may be achieved.

Adolescent↗

PubMed1997

Distinct somatic genetic changes associated with tumor progression in carriers of BRCA1 and BRCA2 germ-line mutations.

BRCA1 and BRCA2 mutations confer increased risk for development of breast cancer, but a number of additional, currently largely unknown, somatic genetic defects must also accumulate in the breast epithelial cells before malignancy develops. To evaluate the nature of these additional somatic genetic defects, we performed a genome-wide survey by comparative genomic hybridization on breast cancers from 21 BRCA1 mutation carriers, 15 BRCA2 mutation carriers, and 55 unselected controls. The total number of genetic changes was almost two times higher in tumors from both BRCA1 and BRCA2 mutation carriers than in the control group. In BRCA1 tumors, losses of 5q (86%), 4q (81%), 4p (64%), 2q (40%), and 12q (40%) were significantly more common than in the control group (7-13%). BRCA2 tumors were characterized by a higher frequency of 13q (73%) and 6q (60%) losses and gains of 17q22-q24 (87%) and 20q13 (60%) as compared to the prevalence of these changes in the control group (12-18%). In conclusion, accumulation of somatic genetic changes during tumor progression may follow a unique pathway in individuals genetically predisposed to cancer, especially by the BRCA1 gene. Activation or loss of genes in the affected chromosomal regions may be selected for during tumor progression in cells lacking functional BRCA1 or BRCA2. Identification of such genes could provide targets for therapeutic intervention and early diagnosis.

Adult↗

PubMed1997

Detection of orbital implant infection with technetium 99m-labeled leukocytes.

Orbital implant infection is a rare cause of anophthalmic socket pain. Because of the potential danger of infection spreading to nearby structures, it is of paramount importance to diagnose the condition as soon as possible. Scintigraphy is a method for diagnosis of graft infections by radioisotopic imaging of inflammatory sites. We report on a patient with socket pain 3 months after implantation of an acrylic implant. The socket appearance was normal and there were no signs of infection other than culture-positive socket exudation. Three consecutive computed tomography scans revealed no abnormalities. 99mTc leukocyte scintigraphy revealed white blood cell accumulation at the implantation site. The implant was removed and cultured. This produced Staphylococcus epidermidis and R. equii. A parenteral antibiotic treatment was instituted with subsequent improvement of symptoms. Four months later, after negative scintigraphy, a hydroxyapatite implant was inserted, demonstrating full vascularization on a bone scan after 2 months. Two months later, the patient developed the previous symptoms, with all of the former findings, including positive scintigraphy. The implant was removed, revealing a microabscess on the anterior aspect, producing S. epidermidis on culture. We conclude that scintigraphy using 99mTc-labeled leukocytes is a useful technique in diagnosing low-grade orbital infection.

Acrylic Resins↗

PubMed1997

Malignant nasopharyngeal tumours in Iceland.

From 1965 to 1990, 46 cases of malignant nasopharyngeal tumours were diagnosed in Iceland. The incidence rate is as low as in other Western countries, 0.6/100,000 per year. Histo-pathological diagnosis were as follows: Undifferentiated carcinoma 45%; squamous cell carcinoma 30%; non-keratinizing carcinoma 7%; and plasmacytoma 9%; lymphoma 7%; rhabdomyosarcoma 2%. Four per cent were diagnosed at stage I, 13% at stage II, 29% at stage III and 54% at stage IV. The overall crude survival at 10 years from diagnosis was 28.3%. The following factors were found to have a prognostic value: Stage of disease, size of tumour (T-classification) and age at diagnosis. Nodal stage (N-classification) alone and sex were not found to be prognostic factors. There was no difference in survival among the different WHO types of cancer. Patients with carcinoma were all treated with radiotherapy. The survival of those who received more than 60 Gy was better than of those who received 60 Gy or less (p = 0.04).

Adolescent↗

PubMed1996

High prevalence of the 999del5 mutation in icelandic breast and ovarian cancer patients.

Studies on Icelandic breast cancer families have shown that most of them segregate a 999del5 BRCA2 mutation. Here, we report the frequency of the 999del5 BRCA2 mutation in an Icelandic control population and four different groups of cancer patients diagnosed with (a) breast cancer; (b) ovarian cancer; (c) prostate cancer (patients younger than 65 years); and (d) other cancer types. The proportions of individuals carrying the mutation were 0.4% in the control population and in the patient groups 8.5%, 7.9%, 2.7%, and 1.0%, respectively. Our results indicate that BRCA2 confers a very high risk of breast cancer and is responsible for a substantial fraction of breast and ovarian cancer in Iceland, but only a small proportion of other cancers.

Adult↗

PubMed1996

Male breast cancer in Iceland.

All malignant tumours of the male breast diagnosed in Iceland during the 40-year period 1955-1994 were studied with regard to histological classification, tumour grading and flow cytometric analysis. Of 31 malignant tumours diagnosed, 29 were primary breast carcinomas. Male breast carcinoma constitutes 1% of all breast malignancies in Iceland and 0.25% of all malignant tumours in males. About 80% of the male breast carcinomas were diagnosed during the latter half of the study period. The mean age of the patients was 66.3 years and the left-to-right ratio was 1.9:1.0. Right-sided tumours appeared to be more aggressive. The mean tumour size was 2.6 cm. The vast majority of the carcinomas (79%) were of the infiltrating ductal type. Of these 21.7% were grade I, 43.5% were grade II and 34.8% grade III. Papillary carcinomas made up 17% of the total. These occurred in slightly older patients than the infiltrating ductal carcinomas and were diploid tumours. In this study 57% of the tumours were found to be aneuploid, but nearly 70% of the invasive ductal carcinomas NOS were aneuploid. In general, the aneuploid tumours were larger, of higher average histological grade and had a higher mean S-phase value. The overall mean S-phase fraction was 7.2% which is similar to that found in female breast tumours in Iceland. It is concluded that male-to-female ratio of breast carcinoma in Iceland is similar to that found in other Western countries. The age-standardised incidence has increased considerably in the last 20 years, in contrast to the rates reported from most other countries. Papillary tumours are unusually common in Icelandic males.

Aged↗