Dataset Information

GWAS of Breast Cancer in the African Diaspora

ABSTRACT:

The paucity of data on the genetic epidemiology of breast cancer for racial/ethnic groups other than those of European ancestry hinders the development of innovative interventions to reduce health disparities. Women in the African Diaspora experience a disproportionate burden of pre-menopausal breast cancer in comparison to all other races for reasons that remain unknown and understudied. This higher proportion of early-onset breast cancer might suggest a stronger genetic component in these populations. Genome-wide association studies (GWAS) have revealed several genetic loci that confer risk of breast cancer. Because all GWAS started the discovery stage in women of European ancestry and replicated mainly in women of European ancestry, we propose a novel approach for a GWAS in indigenous African women to identify alleles associated with breast cancer risk which will then be replicated in other populations. This innovative design builds on our current understanding of the etiologic heterogeneity in breast cancer and the distribution of breast cancer molecular subtypes which differ between women of African ancestry and women of European ancestry. The major objective of the proposed studies is to get to the "root" causes of breast cancer by identifying breast cancer risk alleles in a pooled sample of women of African ancestry and to replicate our findings in other populations.

To achieve this objective, we conducted a case control study of breast cancer in women of African ancestry, including Africans living in Nigeria, African Americans and African Barbadians. We will genotype ~3800 individuals using the Illumina HumanOmni2.5-Quad platform. We will conduct both standard and novel genetic analyses of the data to map genes associated with breast cancer susceptibility, verify genotyping and carry out fine-mapping studies in genes or regions showing association with breast cancer risk, and replicate in other African American and non-African American populations. By pooling unique resources from studies throughout the African Diaspora, this study has the potential to identify risk alleles in several genes that contribute to increased breast cancer risk and may have implications for early detection, prognosis and treatment of breast cancer in ALL women. This should ultimately lead to improved outcomes for those who suffer a disproportionate burden of early-onset breast cancer.

PROVIDER: phs000383 | dbGaP |

SECONDARY ACCESSION(S): PRJNA75839PRJNA75837

REPOSITORIES: dbGaP

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Dataset's files

Source:

			Action	DRS
	GapExchange_phs000383.v1.p1.xml	Xml
	dbGaPEx2.1.5.xsd	Other
	Study_Report.phs000383.CIDR_BreastCA_Olopade.v1.p1.MULTI.pdf	Pdf
	manifest_phs000383.CIDR_BreastCA_Olopade.v1.p1.c3.HRGM.pdf	Pdf
	datadict_v2.xsl	Other

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Project description:<p>The paucity of data on the genetic epidemiology of breast cancer for racial/ethnic groups other than those of European ancestry hinders the development of innovative interventions to reduce health disparities. Women in the African Diaspora experience a disproportionate burden of pre-menopausal breast cancer in comparison to all other races for reasons that remain unknown and understudied. This higher proportion of early-onset breast cancer might suggest a stronger genetic component in these populations. Genome-wide association studies (GWAS) have revealed several genetic loci that confer risk of breast cancer. Because all GWAS started the discovery stage in women of European ancestry and replicated mainly in women of European ancestry, we propose a novel approach for a GWAS in indigenous African women to identify alleles associated with breast cancer risk which will then be replicated in other populations. This innovative design builds on our current understanding of the etiologic heterogeneity in breast cancer and the distribution of breast cancer molecular subtypes which differ between women of African ancestry and women of European ancestry. The major objective of the proposed studies is to get to the "root" causes of breast cancer by identifying breast cancer risk alleles in a pooled sample of women of African ancestry and to replicate our findings in other populations.</p> <p>To achieve this objective, we conducted a case control study of breast cancer in women of African ancestry, including Africans living in Nigeria, African Americans and African Barbadians. We will genotype ~3800 individuals using the Illumina HumanOmni2.5-Quad platform. We will conduct both standard and novel genetic analyses of the data to map genes associated with breast cancer susceptibility, verify genotyping and carry out fine-mapping studies in genes or regions showing association with breast cancer risk, and replicate in other African American and non-African American populations. By pooling unique resources from studies throughout the African Diaspora, this study has the potential to identify risk alleles in several genes that contribute to increased breast cancer risk and may have implications for early detection, prognosis and treatment of breast cancer in ALL women. This should ultimately lead to improved outcomes for those who suffer a disproportionate burden of early-onset breast cancer.</p>

Project description:Background: Differences in breast cancer outcomes according to race/ethnicity have been reported. Hispanic/Latino (H/L) populations are a genetically admixed and heterogeneous group, with variable fractions of European, Indigenous American and African ancestries. Some studies suggest that breast cancer-specific mortality is higher in U.S. Hispanic/Latinas compared to non-Hispanic Whites (NHW) even after adjustment for socioeconomic status and education. The molecular profile of breast cancer has been widely described in NHWs but equivalent knowledge is lacking in Hispanic/Latinas. We have previously reported that the most prevalent breast cancer intrinsic subtype in Colombian H/L women was Luminal B as defined by surrogate St. Gallen 2013 criteria. In this study we explored ancestry-associated differences in molecular profiles of Luminal B tumors among these highly admixed women. Methods: We performed whole-transcriptome RNA-seq analysis in 42 Luminal tumors (21 Luminal A and 21 Luminal B) from Colombian women. Genetic ancestry was estimated from a panel of 80 ancestry-informative markers (AIM). We categorized patients according to Luminal subtype and to the proportion of European and Indigenous American ancestry and performed differential expression analysis comparing Luminal B against Luminal A tumors according to the assigned ancestry groups. Results: We found 5 genes potentially modulated by genetic ancestry: ERBB2 (Fold Change = 2.367, padj < 0.01), GRB7 (Fold Change = 2.327, padj < 0.01), GSDMB (Fold Change = 1.723, padj < 0.01, MIEN1 (Fold Change = 2.195, padj < 0.01 and ONECUT2 (Fold Change = 2.204, padj < 0.01). In the replication set we found a statistical significant association between European ancestry fraction and the expression levels of ERBB2 (p = 0.02, B = 2.49) and ONECUT2 (p = 0.04, B = -4.87). We also observed statistical significant associations for ERBB2 expression with Indigenous American ancestry (p < 0.001, B = 3.82). This association was not biased by the distribution of HER2+ tumors among the groups analyzed. Conclusions: Our results suggest that genetic ancestry in Hispanic/Latina women might modify ERBB2 gene expression in Luminal tumors. Further analyses are needed to confirm these findings and explore their prognostic value.

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GWAS of Breast Cancer in the African Diaspora

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