Genetics of rheumatic fever and rheumatic heart disease

Rheumatic heart disease (RHD) is a complication of group A streptococcal infection that results from a complex interaction between the genetic make-up of the host, the infection itself and several other environmental factors, largely reflecting poverty. RHD is estimated to affect 33.4 million people and results in 10.5 million disability-adjusted life-years lost globally. The disease has long been considered heritable but still little is known about the host genetic factors that increase or reduce the risk of developing RHD. In the 1980s and 1990s, several reports linked the disease to the human leukocyte antigen (HLA) locus on chromosome 6, followed in the 2000s by reports implicating additional candidate regions elsewhere in the genome. Subsequently, the search for susceptibility loci has been reinvigorated by the use of genome-wide association studies (GWAS) through which millions of variants can be tested for association in thousands of individuals. Early findings implicate not only HLA, particularly the HLA-DQA1 to HLA-DQB1 region, but also the immunoglobulin heavy chain locus, including the IGHV4-61 gene segment, on chromosome 14. In this Review, we assess the emerging role of GWAS in assessing RHD, outlining both the advantages and disadvantages of this approach. We also highlight the potential use of large-scale, publicly available data and the value of international collaboration to facilitate comprehensive studies that produce findings that have implications for clinical practice. Rheumatic heart disease is a complication of group A streptococcal infection and rheumatic fever. In this Review, Muhamed and colleagues assess the emerging role of genome-wide association studies in detecting loci associated with genetic susceptibility to rheumatic heart disease. Key points Rheumatic heart disease (RHD) remains a public health priority in low-income and middle-income countries, despite being nearly eliminated in high-income countries. A combination of risk factors can contribute to increased susceptibility to group A streptococcal infection, rheumatic fever and, ultimately, RHD. The risk of rheumatic fever in an individual with a family history of RHD is nearly fivefold higher than that in an individual with no family history of RHD. Plausible susceptibility loci have been evaluated on chromosome 6 in the human leukocyte antigen (HLA) region and elsewhere in the human genome. Initial findings from genome-wide association studies (GWAS), through which m