Figure 2

Complex pattern of inheritance of arthritis phenotype in the IIJ strain. Pedigrees representing the inheritance of the arthritis phenotype in multiple generations of IIJ mice after intercrossing or backcrossing. The arthritis incidence in a particular phenotypic cross in each generation is shown as a percentage above the progeny. The number inside each symbol represents the number of progeny of that sex and phenotype. For conciseness, the results of a particular phenotypic cross were combined within a line for each generation. (A) Pedigree of the first four generations of the IIJ strain. One of the nontransgenic arthritic males from the 5B6 colony was crossed with SJL/J females to establish the IIJ strain. The strain was then maintained by sibling-sibling mating. (B) AR IIJ mice from various generations (noted as F3, F5 and F6 next to cross) were backcrossed to SJL/J, and the progeny were tracked for disease.