Association of rs7719175, located in the IL13 gene promoter, with Schistosoma haematobium infection levels and identification of a susceptibility haplotype.

Urinary schistosomiasis is a parasitic disease caused by Schistosoma haematobium helminths. S. haematobium eggs may remain trapped within the bladder or the ureter walls, causing major pathological disorders in the urogenital system. The polymorphism rs1800925(C/T) of the IL13 gene promoter, which is functional, has previously been associated with susceptibility to S. haematobium infection. The aim of this study was to further our understanding and to determine whether, in the 5q31-q33 region, rs1800925 affects infection levels alone or in synergy with other polymorphisms. After sequencing the IL13 promoter and increasing the single-nucleotide polymorphism density, we performed a linkage disequilibrium analysis between rs1800925 and the other markers in a Malian population. Multivariate linear regression analysis and electrophoretic mobility shift assay (EMSA) were performed to characterized markers in linkage disequilibrium with rs1800925. An additional polymorphism, rs7719175, in the IL13 promoter was associated with controlling infection levels in multivariate analysis. The haplotype rs7719175T-rs1800925C was associated with high infection levels. EMSA indicated that rs7719175 affects the binding of transcriptional factors to the promoter region. Polymorphisms rs7719175 and rs1800925 have a synergistic role in the control of infection levels caused by S. haematobium and using them as a haplotype allows a better discrimination between infected subjects.