Evaluating the impact of altered gene expression on uterine fibroid risk in African ancestry populations - PROJECT SUMMARY Uterine fibroids, benign tumors of the uterus, affect 77% of women by menopause in the U.S. and account for up to $34 billion in annual healthcare costs. Black women have at least a two-fold higher risk of fibroids than White women, develop fibroids at younger ages, are more likely to have a clinical diagnosis, and are more likely to have a hysterectomy. Black women are also more likely than White women to have larger and more numerous fibroids. Fibroids are also highly heritable. We have shown associations between increasing African ancestry and fibroid risk that risk varies by African geographic region. We will leverage VUMC’s extensive research infrastructure in Nigeria, our state-of-the-art tissue collection, -omics expertise, and the high level of genetic diversity within Africa-origin populations to test the hypothesis that Nigerian women have stronger risk for fibroids than US Black women. Nigeria is an ideal locale to study these issues as ancestry from Nigerian populations represents a large proportion of the African American genome. Several large-scale genome- wide association studies (GWAS) of fibroid risk have identified multiple fibroid risk loci. However, the mechanisms by which these genes function in the uterus or in fibroid tumors remain poorly defined. Within this grant we will use bulk RNA (RNAseq) and single cell RNAseq (scRNAseq) to better understand the mechanisms by which GWAS identified loci function in fibroid risk in African ancestry women. We will conduct the following specific aims: 1. Test for the association of known and novel fibroid GWAS loci among Nigerian women and identify loci associated with gene expression in myometrium. We hypothesize that effect sizes are larger for fibroid risk loci among Nigerian women and these loci associate with gene expression. We will run bulk RNAseq on 1,000 myometrium samples (500 discovery and 500 validation) and conduct germline low pass sequencing from whole blood from the 3,000 with 1,000 overlapping individuals. 2. Detect cell-specific gene expression unique to normal or fibroid tissue in African ancestry women. We hypothesize that there are differences in cell-type specific gene expression across normal and fibroid uteri. Using overlapping samples from Aim 1, we will run scRNAseq on fibroid tumors and normal myometrial tissue (75 non-fibroid, and 75 fibroid tissues from US Blacks, age-matched). 3. Build a myometrial tissue eQTL atlas and gene expression prediction models. We hypothesize that eQLTs identified from Aim 1 and 2 can be used to develop predicted gene expression models. Combining genotypes and bulk RNAseq data generated in Aim 1 and scRNAseq data from Aim 2, we construct bulk and cell-specific predicted gene expression models. We will then conduct a multi-stage predicted gene expression association analyses using GWAS summary statistics and data. We propose an efficient and cost-effective approach to identify functional loci associated with fibroid determinants by developing a uterine tissue gene expression reference in Black women.
