Figure 3.vacA polymorphism. Like cagA, vacA contains polymorphism that results in VacA toxins with varying degrees of virulence. Each region of the gene has multiple alleles (indicated by arrows), which can combine in any combination. (A) While the s-, i-, and m-regions are always present, the presence of the d-region is termed d1. (B) VacA that contains a 69–89 base pair deletion between the i- and m-regions is termed d2. Figure was modified from.¹³⁵