Publications by authors named "Jacklyn N Hellwege"

41 Publications

A single genetic locus controls both expression of DPEP1/CHMP1A and kidney disease development via ferroptosis.

Nat Commun 2021 08 23;12(1):5078. Epub 2021 Aug 23.

Department of Medicine, Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.

Genome-wide association studies (GWAS) have identified loci for kidney disease, but the causal variants, genes, and pathways remain unknown. Here we identify two kidney disease genes Dipeptidase 1 (DPEP1) and Charged Multivesicular Body Protein 1 A (CHMP1A) via the triangulation of kidney function GWAS, human kidney expression, and methylation quantitative trait loci. Using single-cell chromatin accessibility and genome editing, we fine map the region that controls the expression of both genes. Mouse genetic models demonstrate the causal roles of both genes in kidney disease. Cellular studies indicate that both Dpep1 and Chmp1a are important regulators of a single pathway, ferroptosis and lead to kidney disease development via altering cellular iron trafficking.
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http://dx.doi.org/10.1038/s41467-021-25377-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8382756PMC
August 2021

Mapping the genetic architecture of human traits to cell types in the kidney identifies mechanisms of disease and potential treatments.

Nat Genet 2021 09 12;53(9):1322-1333. Epub 2021 Aug 12.

Department of Medicine, Renal Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, PA, USA.

The functional interpretation of genome-wide association studies (GWAS) is challenging due to the cell-type-dependent influences of genetic variants. Here, we generated comprehensive maps of expression quantitative trait loci (eQTLs) for 659 microdissected human kidney samples and identified cell-type-eQTLs by mapping interactions between cell type abundances and genotypes. By partitioning heritability using stratified linkage disequilibrium score regression to integrate GWAS with single-cell RNA sequencing and single-nucleus assay for transposase-accessible chromatin with high-throughput sequencing data, we prioritized proximal tubules for kidney function and endothelial cells and distal tubule segments for blood pressure pathogenesis. Bayesian colocalization analysis nominated more than 200 genes for kidney function and hypertension. Our study clarifies the mechanism of commonly used antihypertensive and renal-protective drugs and identifies drug repurposing opportunities for kidney disease.
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http://dx.doi.org/10.1038/s41588-021-00909-9DOI Listing
September 2021

Evidence that geographic variation in genetic ancestry associates with uterine fibroids.

Hum Genet 2021 Oct 23;140(10):1433-1440. Epub 2021 Jul 23.

Vanderbilt Genetics Institute, Vanderbilt University, Nashville, TN, USA.

Uterine fibroids disproportionately impact Black women. Evidence suggests Black women have earlier onset and higher cumulative risk. This risk disparity may be due an imbalance of risk alleles in one parental geographic ancestry subgroup relative to others. We investigated ancestry proportions for the 1000 Genomes phase 3 populations clustered into six geographic groups for association with fibroid traits in Black women (n = 583 cases, 797 controls) and White women (n = 1195 cases, 1164 controls). Global ancestry proportions were estimated using ADMIXTURE. Dichotomous (fibroids status and multiple fibroid status) and continuous outcomes (volume and largest dimension) were modeled for association with ancestry proportions using logistic and linear regression adjusting for age. Effect estimates are reported per 10% increase in genetically inferred ancestry proportion. Among Black women, West African (WAFR) ancestry was associated with fibroid risk, East African ancestry was associated with risk of multiple fibroids, Northern European (NEUR) ancestry was protective for multiple fibroids, Southern European ancestry was protective for fibroids and multiple fibroids, and South Asian (SAS) ancestry was positively associated with volume and largest dimension. In White women, NEUR ancestry was protective for fibroids, SAS ancestry was associated with fibroid risk, and WAFR ancestry was positively associated with volume and largest dimension. These results suggest that a proportion of fibroid risk and fibroid trait racial disparities are due to genetic differences between geographic groups. Further investigation at the local ancestry and single variant levels may yield novel insights into disease architecture and genetic mechanisms underlying ethnic disparities in fibroid risk.
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http://dx.doi.org/10.1007/s00439-021-02322-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8463481PMC
October 2021

Genetic Thyrotropin Regulation of Atrial Fibrillation Risk Is Mediated Through an Effect on Height.

J Clin Endocrinol Metab 2021 06;106(7):2124-2132

Department of Biomedical Informatics & Center for Precision Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.

Context: A genetic predisposition to lower thyrotropin (TSH) levels is associated with increased atrial fibrillation (AF) risk through undefined mechanisms.

Objective: Defining the genetic mediating mechanisms could lead to improved targeted therapies to mitigate AF risk.

Methods: We used 2-sample mendelian randomization (MR) to test associations between TSH-associated single-nucleotide variations and 16 candidate mediators. We then performed multivariable mendelian randomization (MVMR) to test for a significant attenuation of the genetic association between TSH and AF, after adjusting for each mediator significantly associated with TSH.

Results: Four candidate mediators (free thyroxine, systolic blood pressure, heart rate, and height) were significantly inversely associated with genetically predicted TSH after adjusting for multiple testing. In MVMR analyses, adjusting for height significantly decreased the magnitude of the association between TSH and AF from -0.12 (SE 0.02) occurrences of AF per SD change in height to -0.06 (0.02) (P = .005). Adjusting for the other candidate mediators did not significantly attenuate the association.

Conclusion: The genetic association between TSH and increased AF risk is mediated, in part, by taller stature. Thus, some genetic mechanisms underlying TSH variability may contribute to AF risk through mechanisms determining height occurring early in life that differ from those driven by thyroid hormone-level elevations in later life.
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http://dx.doi.org/10.1210/clinem/dgab272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8208678PMC
June 2021

Associations of biogeographic ancestry with hypertension traits.

J Hypertens 2021 04;39(4):633-642

Vanderbilt Genetics Institute, Vanderbilt University.

Objectives: Ethnic disparities in hypertension prevalence are well documented, though the influence of genetic ancestry is unclear. The aim of this study was to evaluate associations of geographic genetic ancestry with hypertension and underlying blood pressure traits.

Methods: We tested genetically inferred ancestry proportions from five 1000 Genomes reference populations (GBR, PEL, YRI, CHB, and LWK) for association with four continuous blood pressure (BP) traits (SBP, DBP, PP, MAP) and the dichotomous outcomes hypertension and apparent treatment-resistant hypertension in 220 495 European American, 59 927 African American, and 21 273 Hispanic American individuals from the Million Veteran Program. Ethnicity stratified results were meta-analyzed to report effect estimates per 10% difference for a given ancestry proportion in all samples.

Results: Percentage GBR was negatively associated with BP (P = 2.13 × 10-19, 7.92 × 10-8, 4.41 × 10-11, and 3.57 × 10-13 for SBP, DBP, PP, and MAP, respectively; coefficient range -0.10 to -0.21 mmHg per 10% increase in ancestry proportion) and was protective against hypertension [P = 2.59 × 10-5, odds ratio (OR) = 0.98] relative to other ancestries. YRI percentage was positively associated with BP (P = 1.63 × 10-23, 1.94 × 10-26, 0.012, and 3.26 × 10-29 for SBP, DBP, PP, and MAP, respectively; coefficient range 0.06-0.32 mmHg per 10% increase in ancestry proportion) and was positively associated with hypertension risk (P = 3.10 × 10-11, OR = 1.04) and apparent treatment-resistant hypertension risk (P = 1.86 × 10-4, OR = 1.04) compared with other ancestries. Percentage PEL was inversely associated with DBP (P = 2.84 × 10-5, beta = -0.11 mmHg per 10% increase in ancestry proportion).

Conclusion: These results demonstrate that risk for BP traits varies significantly by genetic ancestry. Our findings provide insight into the geographic origin of genetic factors underlying hypertension risk and establish that a portion of BP trait ethnic disparities are because of genetic differences between ancestries.
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http://dx.doi.org/10.1097/HJH.0000000000002701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8362794PMC
April 2021

Discovery of rare variants associated with blood pressure regulation through meta-analysis of 1.3 million individuals.

Nat Genet 2020 12 23;52(12):1314-1332. Epub 2020 Nov 23.

Department of Clinical Biochemistry, Herlev and Gentofte Hospital, Copenhagen University Hospital, Herlev, Denmark.

Genetic studies of blood pressure (BP) to date have mainly analyzed common variants (minor allele frequency > 0.05). In a meta-analysis of up to ~1.3 million participants, we discovered 106 new BP-associated genomic regions and 87 rare (minor allele frequency ≤ 0.01) variant BP associations (P < 5 × 10), of which 32 were in new BP-associated loci and 55 were independent BP-associated single-nucleotide variants within known BP-associated regions. Average effects of rare variants (44% coding) were ~8 times larger than common variant effects and indicate potential candidate causal genes at new and known loci (for example, GATA5 and PLCB3). BP-associated variants (including rare and common) were enriched in regions of active chromatin in fetal tissues, potentially linking fetal development with BP regulation in later life. Multivariable Mendelian randomization suggested possible inverse effects of elevated systolic and diastolic BP on large artery stroke. Our study demonstrates the utility of rare-variant analyses for identifying candidate genes and the results highlight potential therapeutic targets.
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http://dx.doi.org/10.1038/s41588-020-00713-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7610439PMC
December 2020

Blunted PTH response to vitamin D insufficiency/deficiency and colorectal neoplasia risk.

Clin Nutr 2021 05 6;40(5):3305-3313. Epub 2020 Nov 6.

Division of Epidemiology, Vanderbilt Ingram Cancer Center, Department of Medicine, Vanderbilt University School of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37203, USA. Electronic address:

Background & Aims: In contrast to many observational studies, large-scale randomized trials do not support the protective role of vitamin D for the prevention of colorectal neoplasia. However, in previous studies, individuals with blunted parathyroid hormone (PTH) response to vitamin D insufficiency/deficiency (BPRVID), were not differentiated from those with high PTH response to vitamin D insufficiency/deficiency (HPRVID). Individuals with BPRVID are responsive to magnesium treatment, particularly treatment of magnesium plus vitamin D while those with HPRVID are responsive to vitamin D treatment. We prospectively compared these two distinct groups (i.e. BPRVID and HPRVID) for risk of incident adenoma, metachronous adenoma, and incident colorectal cancer (CRC) METHODS: Three nested case-control studies in the Prostate, Lung, Colorectal and Ovarian Cancer (PLCO) Screening Trial.

Results: We found optimal 25(OH)D levels were associated with a significantly reduced risk of CRC, primarily among women. The associations between 25(OH)D and CRC risk significantly differed by PTH levels, particularly among women. Compared to individuals with optimal levels for both 25(OH)D and PTH, all others were at an elevated risk of incident CRC, primarily in women. We found those with BPRVID had 2.56-fold significantly increased risk of CRC compared to 1.65-fold non-significantly increased risk for those with HPRVID. Among women, we observed those with BPRVID had 4.79-6.25-fold significantly increased risks of incident CRC and adenoma whereas those with HPRVID had 3.65-fold significantly increased risk of CRC.

Conclusions: Individuals with BPRVID are at higher risks of incident adenoma and CRC compared to those with HPRVID, particularly among women.
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http://dx.doi.org/10.1016/j.clnu.2020.10.057DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8099932PMC
May 2021

The polygenic architecture of left ventricular mass mirrors the clinical epidemiology.

Sci Rep 2020 05 5;10(1):7561. Epub 2020 May 5.

Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.

Left ventricular (LV) mass is a prognostic biomarker for incident heart disease and all-cause mortality. Large-scale genome-wide association studies have identified few SNPs associated with LV mass. We hypothesized that a polygenic discovery approach using LV mass measurements made in a clinical population would identify risk factors and diseases associated with adverse LV remodeling. We developed a polygenic single nucleotide polymorphism-based predictor of LV mass in 7,601 individuals with LV mass measurements made during routine clinical care. We tested for associations between this predictor and 894 clinical diagnoses measured in 58,838 unrelated genotyped individuals. There were 29 clinical phenotypes associated with the LV mass genetic predictor at FDR q < 0.05. Genetically predicted higher LV mass was associated with modifiable cardiac risk factors, diagnoses related to organ dysfunction and conditions associated with abnormal cardiac structure including heart failure and atrial fibrillation. Secondary analyses using polygenic predictors confirmed a significant association between higher LV mass and body mass index and, in men, associations with coronary atherosclerosis and systolic blood pressure. In summary, these analyses show that LV mass-associated genetic variability associates with diagnoses of cardiac diseases and with modifiable risk factors which contribute to these diseases.
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http://dx.doi.org/10.1038/s41598-020-64525-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7200691PMC
May 2020

Genome-Wide Association Study of Apparent Treatment-Resistant Hypertension in the CHARGE Consortium: The CHARGE Pharmacogenetics Working Group.

Am J Hypertens 2019 11;32(12):1146-1153

Robertson Center for Biostatistics, University of Glasgow, Glasgow, UK.

Background: Only a handful of genetic discovery efforts in apparent treatment-resistant hypertension (aTRH) have been described.

Methods: We conducted a case-control genome-wide association study of aTRH among persons treated for hypertension, using data from 10 cohorts of European ancestry (EA) and 5 cohorts of African ancestry (AA). Cases were treated with 3 different antihypertensive medication classes and had blood pressure (BP) above goal (systolic BP ≥ 140 mm Hg and/or diastolic BP ≥ 90 mm Hg) or 4 or more medication classes regardless of BP control (nEA = 931, nAA = 228). Both a normotensive control group and a treatment-responsive control group were considered in separate analyses. Normotensive controls were untreated (nEA = 14,210, nAA = 2,480) and had systolic BP/diastolic BP < 140/90 mm Hg. Treatment-responsive controls (nEA = 5,266, nAA = 1,817) had BP at goal (<140/90 mm Hg), while treated with one antihypertensive medication class. Individual cohorts used logistic regression with adjustment for age, sex, study site, and principal components for ancestry to examine the association of single-nucleotide polymorphisms with case-control status. Inverse variance-weighted fixed-effects meta-analyses were carried out using METAL.

Results: The known hypertension locus, CASZ1, was a top finding among EAs (P = 1.1 × 10-8) and in the race-combined analysis (P = 1.5 × 10-9) using the normotensive control group (rs12046278, odds ratio = 0.71 (95% confidence interval: 0.6-0.8)). Single-nucleotide polymorphisms in this locus were robustly replicated in the Million Veterans Program (MVP) study in consideration of a treatment-responsive control group. There were no statistically significant findings for the discovery analyses including treatment-responsive controls.

Conclusion: This genomic discovery effort for aTRH identified CASZ1 as an aTRH risk locus.
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http://dx.doi.org/10.1093/ajh/hpz150DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856621PMC
November 2019

Mapping eGFR loci to the renal transcriptome and phenome in the VA Million Veteran Program.

Nat Commun 2019 08 26;10(1):3842. Epub 2019 Aug 26.

Biomedical Laboratory Research and Development, Tennessee Valley Healthcare System (626)/Vanderbilt University, Nashville, TN, USA.

Chronic kidney disease (CKD), defined by low estimated glomerular filtration rate (eGFR), contributes to global morbidity and mortality. Here we conduct a transethnic Genome-Wide Association Study of eGFR in 280,722 participants of the Million Veteran Program (MVP), with replication in 765,289 participants from the Chronic Kidney Disease Genetics (CKDGen) Consortium. We identify 82 previously unreported variants, confirm 54 loci, and report interesting findings including association of the sickle cell allele of betaglobin among non-Hispanic blacks. Our transcriptome-wide association study of kidney function in healthy kidney tissue identifies 36 previously unreported and nine known genes, and maps gene expression to renal cell types. In a Phenome-Wide Association Study in 192,868 MVP participants using a weighted genetic score we detect associations with CKD stages and complications and kidney stones. This investigation reinterprets the genetic architecture of kidney function to identify the gene, tissue, and anatomical context of renal homeostasis and the clinical consequences of dysregulation.
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http://dx.doi.org/10.1038/s41467-019-11704-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6710266PMC
August 2019

A -Ethnic Genome-Wide Association Study of Uterine Fibroids.

Front Genet 2019 12;10:511. Epub 2019 Jun 12.

Vanderbilt Epidemiology Center, Institute for Medicine and Public Health, Vanderbilt University Medical Center, Nashville, TN, United States.

Uterine fibroids affect up to 77% of women by menopause and account for up to $34 billion in healthcare costs each year. Although fibroid risk is heritable, genetic risk for fibroids is not well understood. We conducted a two-stage case-control meta-analysis of genetic variants in European and African ancestry women with and without fibroids classified by a previously published algorithm requiring pelvic imaging or confirmed diagnosis. Women from seven electronic Medical Records and Genomics (eMERGE) network sites (3,704 imaging-confirmed cases and 5,591 imaging-confirmed controls) and women of African and European ancestry from UK Biobank (UKB, 5,772 cases and 61,457 controls) were included in the discovery genome-wide association study (GWAS) meta-analysis. Variants showing evidence of association in Stage I GWAS ( < 1 × 10) were targeted in an independent replication sample of African and European ancestry individuals from the UKB (Stage II) (12,358 cases and 138,477 controls). Logistic regression models were fit with genetic markers imputed to a 1000 Genomes reference and adjusted for principal components for each race- and site-specific dataset, followed by fixed-effects meta-analysis. Final analysis with 21,804 cases and 205,525 controls identified 326 genome-wide significant variants in 11 loci, with three novel loci at chromosome 1q24 (sentinel-SNP rs14361789; = 4.7 × 10), chromosome 16q12.1 (sentinel-SNP rs4785384; = 1.5 × 10) and chromosome 20q13.1 (sentinel-SNP rs6094982; = 2.6 × 10). Our statistically significant findings further support previously reported loci including SNPs near , and /. We report evidence of ancestry-specific findings for sentinel-SNP rs10917151 in the / locus ( = 1.76 × 10). Ancestry-specific effect-estimates for rs10917151 were in opposite directions (P-Het-between-groups = 0.04) for predominantly African (OR = 0.84) and predominantly European women (OR = 1.16). Genetically-predicted gene expression of several genes including in vagina ( = 4.6 × 10), in esophageal mucosa ( = 8.7 × 10), in multiple tissues including subcutaneous adipose tissue ( = 3.3 × 10), and in skeletal muscle tissue ( = 5.8 × 10) were associated with fibroids. The finding for was supported by SNP-based summary Mendelian randomization analysis. Our study suggests that fibroid risk variants act through regulatory mechanisms affecting gene expression and are comprised of alleles that are both ancestry-specific and shared across continental ancestries.
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http://dx.doi.org/10.3389/fgene.2019.00511DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6582231PMC
June 2019

A catalog of genetic loci associated with kidney function from analyses of a million individuals.

Nat Genet 2019 06 31;51(6):957-972. Epub 2019 May 31.

Diabetes and Cardiovascular Disease-Genetic Epidemiology, Department of Clincial Sciences in Malmö, Lund University, Malmö, Sweden.

Chronic kidney disease (CKD) is responsible for a public health burden with multi-systemic complications. Through trans-ancestry meta-analysis of genome-wide association studies of estimated glomerular filtration rate (eGFR) and independent replication (n = 1,046,070), we identified 264 associated loci (166 new). Of these, 147 were likely to be relevant for kidney function on the basis of associations with the alternative kidney function marker blood urea nitrogen (n = 416,178). Pathway and enrichment analyses, including mouse models with renal phenotypes, support the kidney as the main target organ. A genetic risk score for lower eGFR was associated with clinically diagnosed CKD in 452,264 independent individuals. Colocalization analyses of associations with eGFR among 783,978 European-ancestry individuals and gene expression across 46 human tissues, including tubulo-interstitial and glomerular kidney compartments, identified 17 genes differentially expressed in kidney. Fine-mapping highlighted missense driver variants in 11 genes and kidney-specific regulatory variants. These results provide a comprehensive priority list of molecular targets for translational research.
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http://dx.doi.org/10.1038/s41588-019-0407-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6698888PMC
June 2019

Heritability and genome-wide association study of benign prostatic hyperplasia (BPH) in the eMERGE network.

Sci Rep 2019 04 15;9(1):6077. Epub 2019 Apr 15.

Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.

Benign prostatic hyperplasia (BPH) results in a significant public health burden due to the morbidity caused by the disease and many of the available remedies. As much as 70% of men over 70 will develop BPH. Few studies have been conducted to discover the genetic determinants of BPH risk. Understanding the biological basis for this condition may provide necessary insight for development of novel pharmaceutical therapies or risk prediction. We have evaluated SNP-based heritability of BPH in two cohorts and conducted a genome-wide association study (GWAS) of BPH risk using 2,656 cases and 7,763 controls identified from the Electronic Medical Records and Genomics (eMERGE) network. SNP-based heritability estimates suggest that roughly 60% of the phenotypic variation in BPH is accounted for by genetic factors. We used logistic regression to model BPH risk as a function of principal components of ancestry, age, and imputed genotype data, with meta-analysis performed using METAL. The top result was on chromosome 22 in SYN3 at rs2710383 (p-value = 4.6 × 10; Odds Ratio = 0.69, 95% confidence interval = 0.55-0.83). Other suggestive signals were near genes GLGC, UNCA13, SORCS1 and between BTBD3 and SPTLC3. We also evaluated genetically-predicted gene expression in prostate tissue. The most significant result was with increasing predicted expression of ETV4 (chr17; p-value = 0.0015). Overexpression of this gene has been associated with poor prognosis in prostate cancer. In conclusion, although there were no genome-wide significant variants identified for BPH susceptibility, we present evidence supporting the heritability of this phenotype, have identified suggestive signals, and evaluated the association between BPH and genetically-predicted gene expression in prostate.
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http://dx.doi.org/10.1038/s41598-019-42427-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6465359PMC
April 2019

Trans-ethnic association study of blood pressure determinants in over 750,000 individuals.

Nat Genet 2019 01 21;51(1):51-62. Epub 2018 Dec 21.

MRC Epidemiology Unit, University of Cambridge School of Clinical Medicine, Cambridge, UK.

In this trans-ethnic multi-omic study, we reinterpret the genetic architecture of blood pressure to identify genes, tissues, phenomes and medication contexts of blood pressure homeostasis. We discovered 208 novel common blood pressure SNPs and 53 rare variants in genome-wide association studies of systolic, diastolic and pulse pressure in up to 776,078 participants from the Million Veteran Program (MVP) and collaborating studies, with analysis of the blood pressure clinical phenome in MVP. Our transcriptome-wide association study detected 4,043 blood pressure associations with genetically predicted gene expression of 840 genes in 45 tissues, and mouse renal single-cell RNA sequencing identified upregulated blood pressure genes in kidney tubule cells.
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http://dx.doi.org/10.1038/s41588-018-0303-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6365102PMC
January 2019

Combined linkage and association analysis identifies rare and low frequency variants for blood pressure at 1q31.

Eur J Hum Genet 2019 02 27;27(2):269-277. Epub 2018 Sep 27.

Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.

High blood pressure (BP) is a major risk factor for cardiovascular disease (CVD) and is more prevalent in African Americans as compared to other US groups. Although large, population-based genome-wide association studies (GWAS) have identified over 300 common polymorphisms modulating inter-individual BP variation, largely in European ancestry subjects, most of them do not localize to regions previously identified through family-based linkage studies. This discrepancy has remained unexplained despite the statistical power differences between current GWAS and prior linkage studies. To address this issue, we performed genome-wide linkage analysis of BP traits in African-American families from the Family Blood Pressure Program (FBPP) and genotyped on the Illumina Human Exome BeadChip v1.1. We identified a genomic region on chromosome 1q31 with LOD score 3.8 for pulse pressure (PP), a region we previously implicated in DBP studies of European ancestry families. Although no reported GWAS variants map to this region, combined linkage and association analysis of PP identified 81 rare and low frequency exonic variants accounting for the linkage evidence. Replication analysis in eight independent African ancestry cohorts (N = 16,968) supports this specific association with PP (P = 0.0509). Additional association and network analyses identified multiple potential candidate genes in this region expressed in multiple tissues and with a strong biological support for a role in BP. In conclusion, multiple genes and rare variants on 1q31 contribute to PP variation. Beyond producing new insights into PP, we demonstrate how family-based linkage and association studies can implicate specific rare and low frequency variants for complex traits.
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http://dx.doi.org/10.1038/s41431-018-0277-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6336803PMC
February 2019

Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits.

Nat Genet 2018 10 17;50(10):1412-1425. Epub 2018 Sep 17.

Laboratory of Genetics and Genomics, NIA/NIH, Baltimore, MD, USA.

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future.
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http://dx.doi.org/10.1038/s41588-018-0205-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6284793PMC
October 2018

Genome-wide interaction with the insulin secretion locus MTNR1B reveals CMIP as a novel type 2 diabetes susceptibility gene in African Americans.

Genet Epidemiol 2018 Sep 24;42(6):559-570. Epub 2018 Apr 24.

Center for Genomics and Personalized Medicine Research, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America.

Although type 2 diabetes (T2D) results from metabolic defects in insulin secretion and insulin sensitivity, most of the genetic risk loci identified to date relates to insulin secretion. We reported that T2D loci influencing insulin sensitivity may be identified through interactions with insulin secretion loci, thereby leading to T2D. Here, we hypothesize that joint testing of variant main effects and interaction effects with an insulin secretion locus increases power to identify genetic interactions leading to T2D. We tested this hypothesis with an intronic MTNR1B SNP, rs10830963, which is associated with acute insulin response to glucose, a dynamic measure of insulin secretion. rs10830963 was tested for interaction and joint (main + interaction) effects with genome-wide data in African Americans (2,452 cases and 3,772 controls) from five cohorts. Genome-wide genotype data (Affymetrix Human Genome 6.0 array) was imputed to a 1000 Genomes Project reference panel. T2D risk was modeled using logistic regression with rs10830963 dosage, age, sex, and principal component as predictors. Joint effects were captured using the Kraft two degrees of freedom test. Genome-wide significant (P < 5 × 10 ) interaction with MTNR1B and joint effects were detected for CMIP intronic SNP rs17197883 (P = 1.43 × 10 ; P = 4.70 × 10 ). CMIP variants have been nominally associated with T2D, fasting glucose, and adiponectin in individuals of East Asian ancestry, with high-density lipoprotein, and with waist-to-hip ratio adjusted for body mass index in Europeans. These data support the hypothesis that additional genetic factors contributing to T2D risk, including insulin sensitivity loci, can be identified through interactions with insulin secretion loci.
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http://dx.doi.org/10.1002/gepi.22126DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6160319PMC
September 2018

Genetic Risk Score Is Associated With Prevalence of Advanced Neoplasms in a Colorectal Cancer Screening Population.

Gastroenterology 2018 07 21;155(1):88-98.e10. Epub 2018 Mar 21.

Division of Clinical Epidemiology and Aging Research, German Cancer Research Center, Heidelberg, Germany; German Cancer Consortium, German Cancer Research Center, Heidelberg, Germany; Division of Preventive Oncology, German Cancer Research Center and National Center of Tumor Diseases, Heidelberg, Germany. Electronic address:

Background & Aims: The presence of specific single nucleotide polymorphisms (SNPs) can be used to calculate an individual's risk for colorectal cancer (CRC), called a genetic risk score (GRS). We investigated whether GRS can identify individuals with clinically relevant neoplasms in a screening colonoscopy population.

Methods: We derived a GRS based on 48 SNPs associated with CRC, identified in a comprehensive literature search. We obtained genetic data from 1043 participants (50-79 years old) in a screening colonoscopy study in Germany, recruited from 2005 through 2013 (294 with advanced neoplasms, 249 with non-advanced adenoma (NAAs), and 500 without neoplasms). Each participant was assigned a GRS by aggregating their risk alleles (0, 1, or 2). Risk of advanced neoplasms and NAA according to GRS was calculated by multiple logistic regression. Risk advancement periods were calculated. We replicated our findings using data from a subset of the Tennessee Colorectal Polyp Study.

Results: An increased GRS was associated with higher prevalence of advanced neoplasms, but not NAAs. Participants in the middle and upper tertiles of GRS had a 2.2-fold and 2.7-fold increase in risk, respectively, of advanced neoplasms compared to those in the lower tertile. Adjusted odds ratios (ORs) were 1.09 (95% confidence interval [CI], 0.76-1.57) for NAA in the middle tertile and 1.05 (95% CI, 0.70-1.55) for NAA in the upper tertile. The ORs were largest for proximal advanced neoplasms for participants in the middle tertile (OR, 3.55; 95% CI 1.85-6.82) and the upper tertile (OR, 3.61; 95% CI 1.84-7.10). The risk advancement period for medium vs low GRS was 13.4 years (95% CI 4.8-22.0) and for high vs low GRS was 17.5 years (95% CI, 7.8-27.3).

Conclusions: In a genetic analysis of participants in a CRC screening study in Germany, an increased GRS (based on CRC-associated SNPs) was associated with increased prevalence of advanced neoplasms. These findings might be used in defining risk-adapted screening ages.
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http://dx.doi.org/10.1053/j.gastro.2018.03.030DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6035076PMC
July 2018

Gene-based evaluation of low-frequency variation and genetically-predicted gene expression impacting risk of keloid formation.

Ann Hum Genet 2018 07 27;82(4):206-215. Epub 2018 Feb 27.

Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA.

Keloids are benign dermal tumors occurring approximately 20 times more often in individuals of African descent as compared to individuals of European descent. While most keloids occur sporadically, a genetic predisposition is supported by both familial aggregation of some keloids and large differences in risk among populations. Despite Africans and African Americans being at increased risk over lighter-skinned individuals, little genetic research exists into this phenotype. Using a combination of admixture mapping and exome analysis, we reported multiple common variants within chr15q21.2-22.3 associated with risk of keloid formation in African Americans. Here we describe a gene-based association analysis using 478 African American samples with exome genotyping data to identify genes containing low-frequency variants associated with keloids, with evaluation of genetically-predicted gene expression in skin tissues using association summary statistics. The strongest signal from gene-based association was located in C15orf63 (P-value = 6.6 × 10 ) located at 15q15.3. The top result from gene expression was increased predicted DCAF4 expression (P-value = 5.5 × 10 ) in non-sun-exposed skin, followed by increased predicted OR10A3 expression in sun-exposed skin (P-value = 6.9 × 10 ). Our findings identify variation with putative roles in keloid formation, enhanced by the use of predicted gene expression to support the biological roles of variation identified only though genetic association studies.
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http://dx.doi.org/10.1111/ahg.12245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5993571PMC
July 2018

Genome-Wide Study of Subcutaneous and Visceral Adipose Tissue Reveals Novel Sex-Specific Adiposity Loci in Mexican Americans.

Obesity (Silver Spring) 2018 01 27;26(1):202-212. Epub 2017 Nov 27.

Center for Genomics and Personalized Medicine Research, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA.

Objective: This study aimed to explore the genetic mechanisms of regional fat deposition, which is a strong risk factor for metabolic diseases beyond total adiposity.

Methods: A genome-wide association study of 7,757,139 single-nucleotide polymorphisms (SNPs) in 983 Mexican Americans (n  = 403; n  = 580) from the Insulin Resistance Atherosclerosis Family Study was performed. Association analyses were performed with and without sex stratification for subcutaneous adipose tissue, visceral adipose tissue (VAT), and visceral-subcutaneous ratio (VSR) obtained from computed tomography.

Results: The strongest signal identified was SNP rs2185405 (minor allele frequencies [MAF] = 40%; P = 1.98 × 10 ) with VAT. It is an intronic variant of the GLIS family zinc finger 3 gene (GLIS3). In addition, SNP rs12657394 (MAF = 19%) was associated with VAT in males (P = 2.39×10 ; P = 2.5 × 10 ). It is located intronically in the serum response factor binding protein 1 gene (SRFBP1). On average, male carriers of the variant had 24.6 cm increased VAT compared with noncarriers. Subsequently, genome-wide SNP-sex interaction analysis was performed. SNP rs10913233 (MAF = 14%; P = 3.07 × 10 ) in PAPPA2 and rs10923724 (MAF = 38%; P = 2.89 × 10 ) upstream of TBX15 were strongly associated with the interaction effect for VSR.

Conclusions: Six loci were identified with genome-wide significant associations with fat deposition and interactive effects. These results provided genetic evidence for a differential basis of fat deposition between genders.
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http://dx.doi.org/10.1002/oby.22074DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740005PMC
January 2018

Population Stratification in Genetic Association Studies.

Curr Protoc Hum Genet 2017 10 18;95:1.22.1-1.22.23. Epub 2017 Oct 18.

Vanderbilt Genetics Institute, Division of Epidemiology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.

Population stratification (PS) is a primary consideration in studies of genetic determinants of human traits. Failure to control for PS may lead to confounding, causing a study to fail for lack of significant results, or resources to be wasted following false-positive signals. Here, historical and current approaches for addressing PS when performing genetic association studies in human populations are reviewed. Methods for detecting the presence of PS, including global and local ancestry methods, are described. Also described are approaches for accounting for PS when calculating association statistics, such that measures of association are not confounded. Many traits are being examined for the first time in minority populations, which may inherently feature PS. © 2017 by John Wiley & Sons, Inc.
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http://dx.doi.org/10.1002/cphg.48DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6007879PMC
October 2017

Erratum to: A multi-stage genome-wide association study of uterine fibroids in African Americans.

Hum Genet 2017 11;136(11-12):1497-1498

Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA.

The article "A multi-stage genome-wide association study of uterine fibroids in African Americans", written by Jacklyn N. Hellwege, was originally published Online First without open access. After publication in volume 136, issue 10, page 1363-1373 the author decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to
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http://dx.doi.org/10.1007/s00439-017-1846-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909202PMC
November 2017

Erratum to: A multi-stage genome-wide association study of uterine fibroids in African Americans.

Hum Genet 2017 11;136(11-12):1497-1498

Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA.

The article "A multi-stage genome-wide association study of uterine fibroids in African Americans", written by Jacklyn N. Hellwege, was originally published Online First without open access. After publication in volume 136, issue 10, page 1363-1373 the author decided to opt for Open Choice and to make the article an open access publication. Therefore, the copyright of the article has been changed to
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http://dx.doi.org/10.1007/s00439-017-1846-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5909202PMC
November 2017

A multi-stage genome-wide association study of uterine fibroids in African Americans.

Hum Genet 2017 10 23;136(10):1363-1373. Epub 2017 Aug 23.

Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, USA.

Uterine fibroids are benign tumors of the uterus affecting up to 77% of women by menopause. They are the leading indication for hysterectomy, and account for $34 billion annually in the United States. Race/ethnicity and age are the strongest known risk factors. African American (AA) women have higher prevalence, earlier onset, and larger and more numerous fibroids than European American women. We conducted a multi-stage genome-wide association study (GWAS) of fibroid risk among AA women followed by in silico genetically predicted gene expression profiling of top hits. In Stage 1, cases and controls were confirmed by pelvic imaging, genotyped and imputed to 1000 Genomes. Stage 2 used self-reported fibroid and GWAS data from 23andMe, Inc. and the Black Women's Health Study. Associations with fibroid risk were modeled using logistic regression adjusted for principal components, followed by meta-analysis of results. We observed a significant association among 3399 AA cases and 4764 AA controls at rs739187 (risk-allele frequency = 0.27) in CYTH4 (OR (95% confidence interval) = 1.23 (1.16-1.30), p value = 7.82 × 10). Evaluation of the genetic association results with MetaXcan identified lower predicted gene expression of CYTH4 in thyroid tissue as significantly associated with fibroid risk (p value = 5.86 × 10). In this first multi-stage GWAS for fibroids among AA women, we identified a novel risk locus for fibroids within CYTH4 that impacts gene expression in thyroid and has potential biological relevance for fibroids.
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http://dx.doi.org/10.1007/s00439-017-1836-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5628188PMC
October 2017

Evidence of selection as a cause for racial disparities in fibroproliferative disease.

PLoS One 2017 8;12(8):e0182791. Epub 2017 Aug 8.

Vanderbilt Genetics Institute, Vanderbilt University Medical Center, Nashville, TN, United States of America.

Fibroproliferative diseases are common complex traits featuring scarring and overgrowth of connective tissue which vary widely in presentation because they affect many organ systems. Most fibroproliferative diseases are more prevalent in African-derived populations than in European populations, leading to pronounced health disparities. It is hypothesized that the increased prevalence of these diseases in African-derived populations is due to selection for pro-fibrotic alleles that are protective against helminth infections. We constructed a genetic risk score (GRS) of fibroproliferative disease risk-increasing alleles using 147 linkage disequilibrium-pruned variants identified through genome-wide association studies of seven fibroproliferative diseases with large African-European prevalence disparities. A comparison of the fibroproliferative disease GRS between 1000 Genomes Phase 3 populations detected a higher mean GRS in AFR (mean = 148 risk alleles) than EUR (mean = 136 risk alleles; T-test p-value = 1.75x10-123). To test whether differences in GRS burden are systematic and may be due to selection, we employed the quantitative trait loci (QTL) sign test. The QTL sign test result indicates that population differences in risk-increasing allele burdens at these fibroproliferative disease variants are systematic and support a model featuring selective pressure (p-value = 0.011). These observations were replicated in an independent sample and were more statistically significant (T-test p-value = 7.26x10-237, sign test p-value = 0.015). This evidence supports the role of selective pressure acting to increase frequency of fibroproliferative alleles in populations of African relative to European ancestry populations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182791PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5549739PMC
October 2017
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