Table 2.

Results of single-fiber electromyography in subjects with known mutations

CharacteristicsPatient no.Normal
123456
Mean consecutive difference (MCD) was calculated eliminating pairs with jitter >2 SD above the mean.
* Abnormal values. The normal values are age dependent (Ad Hoc Committee of the AAEM22).
MutationR1281XR1549XF1406C(CAG)22(CAG)22(CAG)22
Age, y424645536660
Duration of illness, y>37>30>207106
Pairs analyzed, n18172120232120
With increased jitter, n9*3*10*012<2
With block, n3*1*1*0000
Mean MCD, μs59*40*51*27.723.835.2Age dependent
Range MCD, μs25–21419–7818–12313–5112–7115–89Age dependent