Since the original linkage study performed by Williams-Blangero et al. [18] identified 13q33 as a quantitative trait locus for resistance to ascariasis (as detected by parasite egg loads) and in this study we detected significant associations between genes underlying the 13q33 locus and specific IgE levels to Ascaris, it is feasible that genetic regulation of antibody production may play a role on Ascaris susceptibility. Here, IGHE is linked to ascariasis.