Huntington's disease is caused by expansion of the CAG repeat in Huntingtin. This repeat has shown tissue-specific instability in mouse models and in a small number of post-mortem human samples. We used small-pool PCR to generate a modified instability index to quantify CAG instability within two brain regions from six human samples where cell loss has been associated with motor and mood symptoms: the motor cortex and cingulate gyrus. The expanded allele demonstrated instability in both regions, with minimal instability in the unexpanded allele. Region-specific differences were not observed, suggesting symptomatology may not be determined by repeat length instability.
Keywords: Huntington’s disease; small-pool PCR.