An association study of TOLL and CARD with leprosy susceptibility in Chinese population

Abstract

Previous genome-wide association studies (GWASs) identified multiple susceptibility loci that have highlighted the important role of TLR (Toll-like receptor) and CARD (caspase recruitment domain) genes in leprosy. A large three-stage candidate gene-based association study of 30 TLR and 47 CARD genes was performed in the leprosy samples of Chinese Han. Of 4363 SNPs investigated, eight SNPs showed suggestive association (P < 0.01) in our previously published GWAS datasets (Stage 1). Of the eight SNPs, rs2735591 and rs4889841 showed significant association (P < 0.001) in an independent series of 1504 cases and 1502 controls (Stage 2), but only rs2735591 (next to BCL10) showed significant association in the second independent series of 938 cases and 5827 controls (Stage 3). Rs2735591 showed consistent association across the three stages (P > 0.05 for heterogeneity test), significant association in the combined validation samples (Pcorrected = 5.54 × 10(-4) after correction for 4363 SNPs tested) and genome-wide significance in the whole GWAS and validation samples (P = 1.03 × 10(-9), OR = 1.24). In addition, we demonstrated the lower expression of BCL10 in leprosy lesions than normal skins and a significant gene connection between BCL10 and the eight previously identified leprosy loci that are associated with NFκB, a major regulator of downstream inflammatory responses, which provides further biological evidence for the association. We have discovered a novel susceptibility locus on 1p22, which implicates BCL10 as a new susceptibility gene for leprosy. Our finding highlights the important role of both innate and adaptive immune responses in leprosy.

Figure 1.

Regional association plots of 1p22 based on the imputation analysis in the expanded GWAS dataset of 706 cases and 5581 controls (13) (See Methods). The P-values for the SNPs (shown as −log₁₀ P-values on the Y-axis) were plotted against their mapping positions (X-axis). Imputed SNPs are denoted as circles, whereas typed SNPs as squares. The color of each SNP reflects its r² value with the confirmed SNP rs2735591. Estimated recombination rates [based on the 1000 Genomes CHB (Han Chinese in Beijing, China) and JPT (Japanese in Tokyo, Japan)] were plotted in light blue. Plots were generated using LocusZoom (39). Top SNP (rs233100) as well as the confirmed SNP (rs2735591) within the LD block of 300 Kb on 1p22.3 region were labeled out.

Figure 2.

Expression analysis of BCL10 in skin tissues. A significantly lower expression of BCL10 was observed in the lesions of patients than the normal skin tissues of healthy controls (P = 3.83 × 10⁻⁵).