| Type | MGI:General | Description | mice show intergenerational instability of the GAA repeat sequence during transmission from parents to offspring through five to 8 generations F1 generation offspring do not display changes, but from the F2 generation onward, expansions or contractions are observed, increasing in size with subsequent backcrosses discreet bimodal expansions of the 82- and 190-GAA repeat units are observed in the F4-5 generations onward; large hyperexpansions as seen in human samples are not detected somatic instability is age-related, with very little or no instability observed at 2 months, but at 3 months, smears of expanding GAA repeats are detected in cerebellar hemisphere, brain stem, cerebellum, and spinal cord tissue 6-month old mice show repeat instability in CNS tissues, but not significantly greater than observed at 3 months |
