Table 1.

Summary of phenotypic observations used to assign motor scores

Phenotype	Score 0	Score 1	Score 2
Hind-limb tremor	Normal	Tremor	N/A
Gait abnormalities	Normal	Gait abnormalities	N/A
Hind-limb splay	Normal	Partially collapsed to the lateral midline	Completely collapsed to the lateral midline
Hind-limb paralysis	Normal	Dragging hind-limbs	N/A
Righting reflex	0 s	< 5 s	> 15 s