The SM1 region on chromosome five identified by Marquet et al. (4) (Figure 1) included the prototypical Th2 cytokines IL4, IL5, IL9, and IL13, these are strong candidates for the QTL gene(s) and SNP and all except IL9 have been found associated with schistosomiasis in candidate gene studies (Table 3). Here, IL9 is linked to schistosomiasis.