Somatic <i>HTT</i> CAG instability differs between B6.<i>Hdh^Q111</i>^/+ and 129.<i>Hdh^Q111</i>^/+ mice.

(A) Representative GeneMapper profiles of HTT CAG repeat size distributions in the tail, striatum and liver of 10-week-old B6.HdhQ111/+ and 129.HdhQ111/+ mice, highlighting the altered contribution of B6 and 129 genetic background to somatic HTT CAG repeat expansion, as previously described [17]. Tail and striatum: B6.HdhQ111/+, CAG116; 129.HdhQ111/+, CAG112. Liver: B6.HdhQ111/+, CAG113; 129.HdhQ111/+, CAG111 (B) Quantification of CAG instability index reveals a statistically significant decrease in somatic HTT CAG instability in the striatum and liver of 129.HdhQ111/+ mice compared to B6.HdhQ111/+ mice. B6.HdhQ111/+ striatum, n = 10, CAG116.9±1.2SD; B6.HdhQ111/+ liver, n = 10, CAG114.3±1.2SD; 129.HdhQ111/+ striatum, n = 12, CAG110.9±1.2SD; 129.HdhQ111/+ liver, n = 9, CAG109.5±1.4SD; Bar graphs represent mean ±SD; ****, p<0.0001.