Fig. 2.

Hazard score for WT/CT18 versus HD46/HD100. Hazard scores calculate the rate of development of neurological deficits over time. Mice with normal polyglutamine length (WT, CT18 ⋄) were compared with transgenics with expanded polyglutamines (HD46, HD100 ▪). WT and CT18 have a near-zero hazard rate for the first 12 months; the rate rises thereafter, suggesting late development of severe symptoms. Conversely, the hazard rate for HD46 and HD100 begins to increase in the first month and continues to climb, indicating that phenotypic expression of HD transgenes with expanded polyglutamines begins early and increases with age.