Higher Lupus Incidence in Asians Linked to Two Novel Genetic Variations

Novel genetic variations known as single nucleotide polymorphisms (SNPs) are associated with a higher incidence of systemic lupus erythematosus (SLE) in Asians, research shows.

The study, “Evaluation of 10 SLE susceptibility loci in Asian populations, which were initially identified in European populations,” was published in the journal Scientific Reports.

A complex network of genetic factors underlies SLE. And the disease incidence varies across the globe, with Asians showing a much higher incidence of lupus than Europeans, which genetic differences between these populations may explain.

A previous study identified 10 new genomic regions in Europeans that researchers associated with SLE susceptibility.

An underlying assumption was that Asians and Europeans shared most of these novel risk loci for SLE. To find out, researchers did genetic-analysis comparisons of the populations, looking at the new SLE-associated SNPs to see genetic similarities and differences between Asians and Europeans. (An SNP is the most common type of genetic variation in our genome.  Basically it is a difference in a single DNA building block, or nucleotide.)

Specifically, they investigated the expression of the 10  SNPs in a study cohort in northern China. To seek independent validation of their findings, they also investigated the SNPs’ expression in three East Asian cohorts.

Genomic analysis showed that Asians and Europeans shared one of the 10 SNPs analyzed:  rs564799 in IL12A. The analysis also confirmed a previously reported shared variation: rs7726414 in TCF7.

“The directions and magnitudes of the allelic effects for most of the 10 SNPs were comparable between Europeans and Asians. However, higher risk allele frequencies and population-attributable risk percentages were observed in Asians than in Europeans,” the researchers wrote.

Overall, “two novel loci reported by SLE genome-wide association studies (GWAS) in Europeans have been significantly replicated in three independent East Asian populations. The comparison of risk allele frequencies and population-attributable risk percentages in Europeans and Asians provides further evidence for a genetic basis of the high incidence of SLE in Asia compared to Europe,” the team concluded.