Mutations in the androgen receptor (AR) gene have been suggested to predispose to male breast cancer (MBC). Studies on MBC patients have not been based on the mutation screening of the entire coding region of the AR and the number of subjects has been small. Therefore, some AR gene alterations may have remained undetected. In the present study, we have comprehensively screened the entire coding region of the AR gene for mutations and also studied the role of AR CAG and GGC repeat lengths as risk factors for MBC in a cohort of 32 Finnish MBC patients. To estimate the possible involvement of the prostate cancer predisposing AR Arg726Leu germ-line mutation in MBC, this mutation was tested in 117 MBC patients. No germ-line mutations were found and the CAG and GGC repeat lengths were similar among MBC cases as among Scandinavian population. Our data indicate that the AR gene does not substantially contribute to MBC predisposition.
BARD1 (BRCA1-associated RING-domain 1) is a tumor suppressor whose protein product interacts with BRCA1, and in which rare somatic and germline mutations have been reported in breast, uterine, and endometrial cancers. We aimed to evaluate whether there are BARD1 genetic variants that contribute to breast cancer risk by screening the gene for germline alterations in 45 Finnish familial breast cancer patients and in seven patients with both breast and ovarian cancer. Two of the missense alterations identified (Cys557Ser and Val507Met) were recently suggested to associate with an increased breast cancer risk. We also analyzed these variants in large and independent series of familial and unselected breast cancer patients and healthy controls. No clearly deleterious mutations were detected in the initial mutation screening. No association of the Cys557Ser and breast cancer risk was observed as the variant was found altogether in 1.4% (16/1181) of familial and 2.2% (34/1565) of unselected breast cancer patients, and in 2.5% (27/1083) of healthy controls. The frequency of the Val-allele of the Val507Met variant was modestly higher among breast cancer patients than among healthy controls, although the difference did not reach statistical significance. No statistically significant association of the Cys557Ser or Val507Met variants with any clinicopathologic parameters was observed. These results suggest that the contribution of the BARD1 germline variants to breast cancer predisposition is very limited, and that neither Cys557Ser nor Val507Met have an effect on familial breast cancer susceptibility.
The etiology and pathogenesis of male breast cancer (MBC) are poorly known. This is due to the fact that the disease is rare, and large-scale genetic epidemiologic studies have been difficult to carry out. Here, we studied the frequency of eight recurrent Finnish BRCA2 founder mutations in a large cohort of 154 MBC patients (65% diagnosed in Finland from 1967 to 1996). Founder mutations were detected in 10 patients (6.5%), eight of whom carried the 9346(-2) A>G mutation. Two novel mutations (4075 delGT and 5808 del5) were discovered in a screening of the entire BRCA2 coding region in 34 samples. However, these mutations were not found in the rest of the 120 patients studied. Patients with positive family history of breast and/or ovarian cancer were often BRCA2 mutation carriers (44%), whereas those with no family history showed a low frequency of involvement (3.6%; P
Laboratory of Atherosclerosis Genetics, Department of Clinical Chemistry, Centre for Laboratory Medicine, Tampere University Hospital, FinnMedi 2 3rd fl., PO Box 2000, FIN-33521, Tampere, Finland.
Matrix metalloproteinase 3 (MMP3) is expressed in human coronary atherosclerotic lesions and is known to be involved in degradation of the plaque and to be co-localized with calcium and fibrin deposits in advanced lesions, indicating a possible role of MMP3 in arterial calcification. The MMP3 gene promoter polymorphism leads to low promoter activity 6A6A, intermediate promoter activity 5A6A and high promoter activity 5A5A genotypes. To determine whether these genotypes predict the extent of atherosclerosis we investigated their association with different types of coronary lesions in an autopsy series of 300 middle-aged white Finnish men (aged 35-69 years) from the Helsinki Sudden Death Study (HSDS). Areas of the coronary wall covered with different atherosclerotic lesions were measured and MMP3 genotypes were determined by PCR and minisequencing. In men >/=53 years the mean area of calcified lesion in the most severely affected coronary artery was significantly associated with the MMP3 genotype (P=0.029). Subjects with high promoter activity genotypes had on average larger calcified lesion areas than those with the low-activity genotype. The MMP3 genotype (P=0.025) persisted as an independent predictor of mean calcified lesion area after stepwise adjustment for age, BMI, hypertension, diabetes, number of affected vessels and smoking. These data provide evidence that the proposed effect of MMP3 in the process of atherogenesis may be modified by the MMP3 genotype.
Chromosomal region 13q21-q22 harbors a putative breast cancer susceptibility gene and has been implicated as a common site for somatic deletions in a variety of malignant tumors. We have built a complete physical clone contig for a region between D13S1308 and AFM220YE9 based on 18 yeast artificial chromosome and 81 bacterial artificial chromosome (BAC) clones linked together by 22 genetic markers and 61 other sequence tagged sites. Combining data from 47 sequenced BACs (as of June 2001), we have assembled in silico an integrated 5.7-Mb genomic map with 90% sequence coverage. This area contains eight known genes, two hypothetical proteins, 24 additional Unigene clusters, and approximately 100 predicted genes and exons. We have determined the cDNA and genomic sequence, and tissue expression profiles for the KIAA1008 protein (homologous to the yeast mitotic control protein dis3+), KLF12 (AP-2 repressor), progesterone induced blocking factor 1, zinc finger transcription factor KLF5, and LIM domain only-7, and for the hypothetical proteins FLJ22624 and FLJ21869. Mutation screening of the five known genes in 19 breast cancer families has revealed numerous polymorphisms, but no deleterious mutations. These data provide a basis and resources for further analyses of this chromosomal region in the development of cancer.
Hereditary hemochromatosis (HH), the most common genetic disease in northern Europeans, is an autosomal recessive disorder of iron metabolism. The association between hepatocellular carcinoma and HFE homozygosity is well documented, but recently HFE hetero- and homozygosity has also been linked to nonhepatocellular malignancies, including female breast cancer. We hypothesized that C282Y and H63D mutations in the HFE gene could contribute to male breast cancer (MBC) and prostate cancer (PC) susceptibility at the population level in Finland. We screened the 2 major HFE mutations, H63D and C282Y, from 116 MBC cases diagnosed in Finland between 1967 and 1996, 843 consecutive unselected PC cases diagnosed at the Pirkanmaa Hospital District between 1999 and 2001 and 480 anonymous blood donor controls by minisequencing. Our results indicate that the frequencies of the HFE mutations do not significantly differ between MBC and PC patients and the population-based controls. No significantly altered risks for MBC or PC among carriers of the 2 variants were observed. However, HFE mutations were seen twice as often among carriers of a common BRCA2 mutation 9346(-2)A-->G compared with the rest of the MBC cases, indicating that HFE may be an MBC risk modifier gene among BRCA2 mutation carriers. In conclusion, our results indicate a minor role for the HFE mutations C282Y and H63D in the causation of MBC and PC, but carriers of both BRCA2 9346(-2)A-->G and an HFE mutation may be at an increased risk.
Laboratory of Cancer Genetics, Tampere University Hospital and Institute of Medical Technology, University of Tampere, Teiskontie 35, FIN-33520 Tampere, Finland. ritva.karhu@uta.fi
Germ-line mutations of the BRCA2 gene are the highest known risk factors for male breast cancer (MBC). Mutations in BRCA2 are mainly point mutations in contrast to BRCA1 in which large genomic rearrangements are quite common. In recent literature, however, genomic alterations of BRCA2 have been linked especially to male breast cancer families. We wanted to screen large genomic deletions and duplications of BRCA2 among Finnish male breast cancer patients.
We used multiplex ligation-dependent probe amplification (MLPA) to detect large genomic rearrangements in the BRCA2 gene among 36 unselected Finnish male breast cancer patients previously tested and found negative for Finnish BRCA1 and BRCA2 founder mutations.
No genomic mutations of BRCA2 nor CHEK2*1100delC point mutations, also included in the assay, were found in this study.
Large genomic BRCA2 rearrangements were not found among our 36 Finnish male breast cancer patients. Screening of large BRCA2 rearrangements is not likely to be advantageous in Finland.
Mutations in the BRCA1 and BRCA2 genes are known to predispose to breast cancer. In Finland, however, only 21% of all breast cancer families have mutations in these genes. Recent studies have shown that large genomic alterations of BRCA1 are common in many countries. Because such alterations will be missed in conventional mutation screening strategies, we decided to screen Finnish breast and ovarian cancer families for genomic alterations by using a multiplex polymerase chain reaction method. The most characteristic features of BRCA1-related breast cancer were used to select patients, namely (1) both breast and ovarian cancer in the family (48 patients), (2) four or more breast cancers in family (22 patients), or (3) young age (
