A special case in point is cystic fibrosis patients where hypermutator population of P. aeruginosa are generated by alteration in the common genes which are involved in mismatch repair (MMR) system comprising mutS, mutL, mutH, and uvrD; in other case, mutator alleles can also result from the presence of antimutator genes, such as mutT, mutY, and mutM [116,117,118]. The gene discussed is OGG1; the disease is cystic fibrosis.