Table 1.

Disability scores

Score	Behavioral phenotype
D0	No motor abnormalities
D1	Slightly slowed or abnormal motor behavior; no dystonia
D2	Mild impairment; sometimes limited ambulation; dystonic postures when disturbed
D3	Moderate impairment; frequent spontaneous dystonic postures
D4	Severe impairment; sustained dystonic postures and limited ambulation
D5	Prolonged immobility in dystonic postures