Genetic studies of systemic lupus erythematosus in Asia: where are we now?

There have been many genetic studies of systemic lupus erythematosus (SLE) in Asia, but the status of SLE in Asia remains unclear. Genes that have been associated with SLE in Caucasians have shown both consistent and inconsistent results in Asians. This prompted us to review studies of SLE-associated genes and compare the degree of consistency according to ethnicity in Asia. We searched PubMed and the national databases in Korea and Japan for SLE genetic studies. A total of 755 articles were found and after applying various exclusion criteria, 442 studies including 17 linkage studies, 2 genome-wide association studies and 423 candidate-gene analyses were reviewed. Nine linkage loci were confirmed to be associated with SLE susceptibility in non-Asians, but the risk locus (16q12) has been identified in only one Asian study. A total of 156 candidate genes were analyzed, of which 92 were studied in Asians. Although there were allelic (HLA-DRB1 and IRF5) or genetic heterogeneity (FCGR gene family), HLA-DRB1, the FCGR gene family, IRF5, STAT4 and MECP2 showed consistent associations with SLE susceptibility across ethnicities. In conclusion, genetic associations often vary with ethnicity, requiring validation in different ethnic groups, and hence future SLE genetic studies will require strong worldwide collaborations.