In Hp positive CD patients a significantly lower prevalence of atrophic gastritis was observed when compared with Hp negative ones (Santarelli et al., 2006). That might be due to the expression of several DNA repair proteins in the inflamed tissue accumulating damaged host DNA (Salama et al., 2013). On the other hand, Hp can gain a foothold in gastrointestinal tract only in the mild CD cases. It is in line with the data, demonstrating the higher inflammation in correlation with lower bacterial upload (Salama et al., 2013). This evidence concerns the gene HP and chronic atrophic gastritis.