Striatal <i>HTT</i> CAG instability in 10-week-old <i>Hdh^Q111/+</i> mice on different genetic backgrounds.

<p>Graphical representation of striatal CAG instability indices from individual (A) B6, 129, (B6x129).F1 and (B6x129).F2 mice, color-coded based on strain genetic background; and from (B) (B6x129).F2 mice color-coded by genotype at the <i>Mlh1</i>, <i>Msh3</i> and <i>Msh2</i> genes (“undetermined” indicates failed genotype). F2 mice homozygous or heterozygous for B6 <i>Mlh1</i> alleles display significantly higher levels of striatal somatic CAG instability than F2 mice homozygous for 129 <i>Mlh1</i> alleles (<i>p</i><0.0001 for both). No relationship could be established between <i>Msh3</i> or <i>Msh2</i> genotype and striatal CAG instability. B6.<i>Hdh^Q111/+</i>, <i>n</i> = 10, CAG116.9±1.2SD; 129.<i>Hdh^Q111/+</i>, <i>n</i> = 12, CAG110.9±1.2SD; (B6x129).<i>Hdh^Q111/+</i> F1, <i>n</i> = 11, CAG114.7±6.4SD; (B6x129).<i>Hdh^Q111/+</i> F2, <i>n</i> = 69, CAG107.7±3.2SD. dbSNP markers located within MMR genes: <i>Mlh1</i>, rs30131926 and rs30174694 (concordant genotypes detected with both markers); <i>Msh3</i>, rs29551174; <i>Msh2</i>, rs33609112 and rs49012398 (concordant genotypes detected with both markers). Horizontal bars represent the mean CAG instability indices of the respective groups.