has_genetic_background_of Person: Jie Zheng strain a has genetic backgroud as strain b is that strain a is derived from strain b and genetic make-up (all its alleles at all loci) of strain a is same to strain b except the mutated gene of interest and a very small amount of other genetic material, generally from one or two other strains. For example, the genetic background of the mutant strains NOD.129S7(B6)-Rag1tm1Mom/J (003729) and NOD.Cg-Rag1tm1Mom Prf1tm1Sdz/SzJ (004848) is NOD.