Figure 3

Evaluation of instability index. (A) To assess the sensitivity of the instability index to the amount of input DNA we calculated instability indices using varying amounts of template DNA (Hdh^{Q 111/}, 5 months, striatum). The coefficient of variation (CV) of the striatal instability index was 2.2%, calculated by dividing the standard deviation of 4 instability index measurements (50, 100, 200, and 300 ng DNA) by the mean instability indices of same 4 measurements. (B) GeneMapper traces and instability indices from bulk DNA (100 ng) and frequency distributions of CAG repeat length obtained using small pool-PCR from striatum, cortex and spleen from an Hdh^{Q 111/+}mouse at 5 months of age. (C) Instability indices from bulk DNA (100 ng) GeneMapper traces were plotted against small pool instability indices (see Methods section) obtained from 9 tissues (striatum, cortex, cerebellum, liver, lung, stomach, skin, heart, ovary) of an Hdh^{Q 111/+}mouse at 5 months of age. The two values were highly correlated.