Figure 4.—

Progeny testing to confirm the distal boundary of the Xce candidate region. A B6CAST N4 backcross female with a crossover between LeeSNPG-I and SNP-843 was crossed to a B6 male and the X inactivation patterns of the N5 progeny were determined. The predicted range of X inactivation patterns for Xce homozygotes (mean = 0.5, SD = 0.1, as suggested by Plenge et al. 2000) and Xce heterozygotes arising from this cross (mean = 0.29, SD = 0.13, from Chadwick and Willard 2005) are indicated. “Recombinant” animals do not carry the heterozygous haplotype of the parent in the DXMit41–DXMit171 candidate region; “nonrecombinant” animals have the same haplotype as the N4 parent. As expected, N5 females with the recombinant haplotype have X inactivation patterns that are generally consistent with an Xce homozygous genotype, while N5 females with the nonrecombinant haplotype have X inactivation patterns consistent with an Xce heterozygous genotype.