ABSTRACT
We carried out a genome-wide association study of breast cancer predisposition with replication and refinement studies involving 6,145 cases and 33,016 controls and identified two SNPs (rs4415084 and rs10941679) on 5p12 that confer risk, preferentially for estrogen receptor (ER)-positive tumors (OR = 1.27, P = 2.5 x 10(-12) for rs10941679). The nearest gene, MRPS30, was previously implicated in apoptosis, ER-positive tumors and favorable prognosis. A recently reported signal in FGFR2 was also found to associate specifically with ER-positive breast cancer.
Subject(s)
Breast Neoplasms/genetics , Chromosomes, Human, Pair 5/genetics , Genetic Predisposition to Disease , Genetic Variation , Receptors, Estrogen/metabolism , Adenocarcinoma/genetics , Adenocarcinoma/metabolism , Adenocarcinoma/pathology , Adult , Aged , Aged, 80 and over , Apoptosis , Breast Neoplasms/metabolism , Breast Neoplasms/pathology , Carcinoma, Ductal, Breast/genetics , Carcinoma, Ductal, Breast/metabolism , Carcinoma, Ductal, Breast/pathology , Carcinoma, Intraductal, Noninfiltrating/genetics , Carcinoma, Intraductal, Noninfiltrating/metabolism , Carcinoma, Intraductal, Noninfiltrating/pathology , Carcinoma, Lobular/genetics , Carcinoma, Lobular/metabolism , Carcinoma, Lobular/pathology , Carcinoma, Medullary/genetics , Carcinoma, Medullary/metabolism , Carcinoma, Medullary/pathology , Case-Control Studies , Cohort Studies , Female , Humans , International Agencies , Male , Middle Aged , Polymorphism, Single Nucleotide , Prognosis , Receptor, Fibroblast Growth Factor, Type 2/genetics , Receptor, Fibroblast Growth Factor, Type 2/metabolism , Ribosomal Proteins/genetics , Ribosomal Proteins/metabolismABSTRACT
Familial clustering studies indicate that breast cancer risk has a substantial genetic component. To identify new breast cancer risk variants, we genotyped approximately 300,000 SNPs in 1,600 Icelandic individuals with breast cancer and 11,563 controls using the Illumina Hap300 platform. We then tested selected SNPs in five replication sample sets. Overall, we studied 4,554 affected individuals and 17,577 controls. Two SNPs consistently associated with breast cancer: approximately 25% of individuals of European descent are homozygous for allele A of rs13387042 on chromosome 2q35 and have an estimated 1.44-fold greater risk than noncarriers, and for allele T of rs3803662 on 16q12, about 7% are homozygous and have a 1.64-fold greater risk. Risk from both alleles was confined to estrogen receptor-positive tumors. At present, no genes have been identified in the linkage disequilibrium block containing rs13387042. rs3803662 is near the 5' end of TNRC9 , a high mobility group chromatin-associated protein whose expression is implicated in breast cancer metastasis to bone.
Subject(s)
Breast Neoplasms/genetics , Chromosomes, Human, Pair 16/genetics , Chromosomes, Human, Pair 2/genetics , Genetic Predisposition to Disease , Genetic Variation , Receptors, Estrogen/biosynthesis , Breast Neoplasms/metabolism , Case-Control Studies , Female , HumansABSTRACT
BACKGROUND: Most, if not all, of the cellular functions of the BRCA1 protein are mediated through heterodimeric complexes composed of BRCA1 and a related protein, BARD1. Some breast-cancer-associated BRCA1 missense mutations disrupt the function of the BRCA1/BARD1 complex. It is therefore pertinent to determine whether variants of BARD1 confer susceptibility to breast cancer. Recently, a missense BARD1 variant, Cys557Ser, was reported to be at increased frequencies in breast cancer families. We investigated the role of the BARD1 Cys557Ser variant in a population-based cohort of 1,090 Icelandic patients with invasive breast cancer and 703 controls. We then used a computerized genealogy of the Icelandic population to study the relationships between the Cys557Ser variant and familial clustering of breast cancer. METHODS AND FINDINGS: The Cys557Ser allele was present at a frequency of 0.028 in patients with invasive breast cancer and 0.016 in controls (odds ratio [OR] = 1.82, 95% confidence interval [CI] 1.11-3.01, p = 0.014). The alleleic frequency was 0.037 in a high-predisposition group of cases defined by having a family history of breast cancer, early onset of breast cancer, or multiple primary breast cancers (OR = 2.41, 95% CI 1.22-4.75, p = 0.015). Carriers of the common Icelandic BRCA2 999del5 mutation were found to have their risk of breast cancer further increased if they also carried the BARD1 variant: the frequency of the BARD1 variant allele was 0.047 (OR = 3.11, 95% CI 1.16-8.40, p = 0.046) in 999del5 carriers with breast cancer. This suggests that the lifetime probability of a BARD1 Cys557Ser/BRCA2 999del5 double carrier developing breast cancer could approach certainty. Cys557Ser carriers, with or without the BRCA2 mutation, had an increased risk of subsequent primary breast tumors after the first breast cancer diagnosis compared to non-carriers. Lobular and medullary breast carcinomas were overrepresented amongst Cys557Ser carriers. We found that an excess of ancestors of contemporary carriers lived in a single county in the southeast of Iceland and that all carriers shared a SNP haplotype, which is suggestive of a founder event. Cys557Ser was found on the same SNP haplotype background in the HapMap Project CEPH sample of Utah residents. CONCLUSIONS: Our findings suggest that BARD1 Cys557Ser is an ancient variant that confers risk of single and multiple primary breast cancers, and this risk extends to carriers of the BRCA2 999del5 mutation.