Table 1.

Regression analysis of htt and CA150 alleles against HD the onset of age

Regression	Variables	R2	ΔR2	P
Model 1	htt	0.468	−	<0.0001
Model 1	htt + CA150	0.474	0.006	0.032
Model 2	htt	0.628	−	<0.0001
Model 2	htt + CA150	0.632	0.004	0.043

Model 1 uses larger htt and CA150 repeat allele sizes as independent variables and age of onset as a dependent variable. Model 2 uses log(age of onset). When CA150 is added as a second independent variable, increase in R² (ΔR²) was detected in models 1 and 2. −, Does not apply.