Table 2: Summary of clinical characteristics between patients with ALS and normal controls in subgroups.

R_limb-onset
( )
R_NC
( )
L_limb-onset
( )
L_NC
( )

Age
( )a
0.520
( )a
0.5150.005 
0.008a
Male, 141419910.307
MMSE 0.051 0.5080.055
ALSFRS n/a n/a0.043
Disease duration (months) n/a n/a0.239
Disease progression rate n/a n/a0.088

R_NC: normal controls corresponding to patients with right limb-onset; L_NC: normal controls corresponding to patients with left limb-onset. aMean age of disease onset in patients with right and left limb-onset and corresponding value.
represents the statistical differences in ALS patients with right limb-onset and corresponding normal controls. represents the statistical differences in ALS patients with left limb-onset and corresponding normal controls. represents the statistical differences in subgroups between ALS patients with right and left limb-onset.