Table 1 Clinical features and nerve conduction studies in five patients of a three-generation family with autosomal dominant DSMA, in five patients with SCA-3, and in three patients with JMA

DiagnosisAge, y/sexThenarHypothenar
Muscle weakness, MRCCMAP, mV*Muscle weakness, MRCCMAP, mV
* Thenar CMAP reference value (mean ± SD): 13.4 ± 3.4.
† Hypothenar CMAP reference value (mean ± SD): 12.3 ± 1.9.
‡ Clinically, this patient showed generalized, not dissociated, small hand muscle atrophy.
DSMA = distal spinal muscular atrophy; SCA-3 = spinocerebellar ataxia type 3; JMA = juvenile muscular atrophy of distal upper extremity; MRC = Medical Research Council examination; CMAP = compound muscle action potential.
DSMA82 /F20511.4
DSMA59 /F47.8512.6
DSMA56 /M40.5513.4
DSMA50 /M4+11.749.8
DSMA27 /M4549
SCA-361 /F45.048.5
SCA-362 /F46.1511.7
SCA-366 /F42.0410.4
SCA-351 /M46.1518.3
SCA-352 /M46.7512.3
JMA34 /M42.0410.8
JMA38 /M44.949.5
JMA29 /M515.743.1