Why the study?
African Americans have a higher hypertension-related stroke burden, making the identification of genetic contributors critical for understanding disease etiology and identifying high-risk individuals.
What are the genetic contributors to incident stroke in African Americans with hypertension, and does a European-derived polygenic risk score improve stroke prediction?
What are the genetic contributors to incident stroke in African Americans with hypertension, and does a European-derived polygenic risk score improve stroke prediction?
The study identifies novel genetic variants associated with incident stroke in hypertensive African Americans and demonstrates that polygenic risk scores derived from European populations do not improve stroke prediction in this demographic.
Background: African Americans (AAs) suffer a higher stroke burden due to hypertension. Identifying genetic contributors to stroke among AAs with hypertension is critical to understanding the genetic basis of the disease, as well as detecting at-risk individuals. Methods: In a population comprising over 10,700 AAs treated for hypertension from the Genetics of Hypertension Associated Treatments (GenHAT) and Reasons for Geographic and Racial Differences in Stroke (REGARDS) studies, we performed an inverse variance-weighted meta-analysis of incident stroke. Additionally, we tested the predictive accuracy of a polygenic risk score (PRS) derived from a European ancestral population in both GenHAT and REGARDS AAs aiming to evaluate cross-ethnic performance. Results: We identified 10 statistically significant ( p < 5.00E-08) and 90 additional suggestive ( p < 1.00E-06) variants associated with incident stroke in the meta-analysis. Six of the top 10 variants were located in an intergenic region on chromosome 18 ( LINC01443-LOC644669 ). Additional variants of interest were located in or near the COL12A1, SNTG1 , PCDH7 , TMTC1 , and NTM genes . Replication was conducted in the Warfarin Pharmacogenomics Cohort (WPC), and while none of the variants were directly validated, seven intronic variants of NTM proximal to our target variants, had a p -value <5.00E-04 in the WPC. The inclusion of the PRS did not improve the prediction accuracy compared to a reference model adjusting for age, sex, and genetic ancestry in either study and had lower predictive accuracy compared to models accounting for established stroke risk factors. These results demonstrate the necessity for PRS derivation in AAs, particularly for diseases that affect AAs disproportionately. Conclusion: This study highlights biologically plausible genetic determinants for incident stroke in hypertensive AAs. Ultimately, a better understanding of genetic risk factors for stroke in AAs may give new insight into stroke burden and potential clinical tools for those among the highest at risk.
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Armstrong et al. (2021) studied this question.
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