Is susceptibility to rheumatic heart disease (RHD) heritable in African individuals, and if so, what are the common genetic variants associated with RHD risk?
In this genome-wide association study of 4809 African individuals, 1 genetic risk locus at 11q24.1 (rs1219406) was associated with RHD at genome-wide significance in Black African individuals but not in other groups, although 1 previously described association was replicated at nominal significance. Polygenic heritability of RHD is estimated at 0.49 in African individuals.
This study suggests that there is an important polygenic component to RHD risk in African individuals, highlighting genetic features exclusive to African individuals as well as genetic similarities with non-African individuals.
Rheumatic heart disease (RHD), a sequela of rheumatic fever characterized by permanent heart valve damage, is the leading cause of cardiac surgery in Africa. However, its pathophysiologic characteristics and genetics are poorly understood. Understanding genetic susceptibility may aid in prevention, control, and interventions to eliminate RHD.
To identify common genetic loci associated with RHD susceptibility in Black African individuals.
Design, Setting, and Participants
This multicenter case-control genome-wide association study (GWAS), the Genetics of Rheumatic Heart Disease, examined more than 7 million genotyped and imputed single-nucleotide variations. The 4809 GWAS participants and 116 independent trio families were enrolled from 8 African countries between December 31, 2012, and March 31, 2018. All GWAS participants and trio probands were screened by use of echocardiography. Data analyses took place from May 15, 2017, until March 14, 2021.
Main Outcomes and Measures
Genetic associations with RHD.
This study included 4809 African participants (2548 RHD cases and 2261 controls; 3301 women [69%]; mean [SD] age, 36.5 [16.3] years). The GWAS identified a single RHD risk locus, 11q24.1 (rs1219406 [odds ratio, 1.65; 95% CI, 1.48-1.82; P = 4.36 × 10−8]), which reached genome-wide significance in Black African individuals. Our meta-analysis of Black (n = 3179) and admixed (n = 1055) African individuals revealed several suggestive loci. The study also replicated a previously reported association in Pacific Islander individuals (rs11846409) at the immunoglobulin heavy chain locus, in the meta-analysis of Black and admixed African individuals (odds ratio, 1.16; 95% CI, 1.06-1.27; P = 1.19 × 10−3). The HLA (rs9272622) associations reported in Aboriginal Australian individuals could not be replicated. In support of the known polygenic architecture for RHD, overtransmission of a polygenic risk score from unaffected parents to affected probands was observed (polygenic transmission disequilibrium testing mean [SE], 0.27 [0.16] SDs; P = .04996), and the chip-based heritability was estimated to be high at 0.49 (SE = 0.12; P = 3.28 × 10−5) in Black African individuals.
Conclusions and Relevance
This study revealed a novel candidate susceptibility locus exclusive to Black African individuals and an important heritable component to RHD susceptibility in African individuals.
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Machipisa T, Chong M, Muhamed B, et al. Association of Novel Locus With Rheumatic Heart Disease in Black African Individuals: Findings From the RHDGen Study. JAMA Cardiol. Published online June 09, 2021. doi:10.1001/jamacardio.2021.1627
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