Mutation in P117 was recessive and linked to chromosome 10. (A) When P117 crossed with one of its siblings, a number of P117 offspring showed impaired IFNα response. When P117 crossed with wild-type mice, none of the F1 mice showed the phenotype. When the F1 mice intercrossed, the phenotype reappeared in the F2 mice. However, the phenotype was not observed in F2 mice of F1 crossed with wild-type mice. Empty squares and circles are unaffected males and females, respectively. Solid squares and circles are affected males and females, respectively. (B) Haplotype analysis was done as described in the Materials and Methods. The physical linkage of the mutation to chromosome in the mutant mice was based on the percentage of the maximum possible χ2 (%max χ2). Solid bar: linked loci. Empty bars: unlinked loci.