Genes at human chromosome 5q31.1 regulate delayed-type hypersensitivity responses associated with Leishmania chagasi infection

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Abstract
Visceral leishmaniasis (VL) caused by Leishmania chagasi is endemic to northeast Brazil. A positive delayed-type hypersensitivity skin test response (DTH+) is a marker for acquired resistance to disease, clusters in families and may be genetically controlled. Twenty-three single nucleotide polymorphisms (SNPs) were genotyped in the cytokine 5q23.3–q31.1 region IRF1-IL5-IL13-IL4-IL9-LECT2-TGFBI in 102 families (323 DTH+; 190 DTH−; 123 VL individuals) from a VL endemic region in northeast Brazil. Data from 20 SNPs were analyzed for association with DTH+/− status and VL using family-based, stepwise conditional logistic regression analysis. Independent associations were observed between the DTH+ phenotype and markers in separate linkage disequilibrium blocks in LECT2 (OR 2.25; P=0.005; 95% CI=1.28–3.97) and TGFBI (OR 1.94; P=0.003; 95% CI=1.24–3.03). VL child/parent trios gave no evidence of association, but the DTH− phenotype was associated with SNP rs2070874 at IL4 (OR 3.14; P=0.006; 95% CI=1.38–7.14), and SNP rs30740 between LECT2 and TGFBI (OR 3.00; P=0.042; 95% CI=1.04–8.65). These results indicate several genes in the immune response gene cluster at 5q23.3–q31.1 influence outcomes of L. chagasi infection in this region of Brazil.