Table 2.
90% to 5% relaxation times (seconds) for different genetic mutations compared to historical normative data.
| Handgrip 1 | Handgrip 6 | Handgrip 1 – Handgrip 6 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Category | N | Mean (SD) | >Upper No. (%) | Mean (SD) | >Upper No. (%) | Mean (SD) | Min | Max | >Upper No. (%) | <Lower No. (%) |
| Normal * | 17 | 0.37 (0.10) | - | 0.43 (0.27) | - | −0.06 (0.20) | −0.70 | 0.15 | - | - |
| Chloride | 30 | 1.74 (1.95) | 20(67) | 0.79 (0.64) | 9 (30) | 0.95 (1.68) | −0.53 | 6.35 | 13(43) | 1 (3) |
| Recessive † | 10 | 2.08 (2.20) | 7(70) | 0.69 (0.56) | 3 (30) | 1.38 (2.02) | −0.06 | 6.35 | 5 (50) | 0 (0) |
| Dominant ‡ | 11 | 1.50 (2.33) | 5 (45) | 0.65 (0.67) | 2 (18) | 0.85 (1.78) | −0.29 | 5.20 | 3 (27) | 0 (0) |
| Unknown § | 9 | 1.66 (1.15) | 8 (89) | 1.06 (0.65) | 4 (44) | 0.60 (1.14) | −0.53 | 3.34 | 5 (56) | 1 (11) |
| Sodium | 31 | 0.77 (0.80) | 12 (39) | 1.13 (1.59) | 8 (26) | −0.37 (1.15) | −4.07 | 1.41 | 3 (10) | 7 (23) |
| T1313M | 11 | 1.20 (1.10) | 6 (55) | 2.35 (2.20) | 6 (55) | −1.22 (1.52) | −4.07 | 0.06 | 0 (0) | 5 (45) |
| R1448H | 5 | 0.30 (0.08) | 0 (0) | 0.47 (0.24) | 0 (0) | −0.11 (0.27) | −0.52 | 0.12 | 0 (0) | 1 (20) |
| G1306A | 5 | 0.52 (0.23) | 2 (40) | 0.47 (0.32) | 1 (20) | 0.04 (0.36) | −0.53 | 0.43 | 1 (20) | 1 (20) |
| M1592V | 2 | 0.20 (0.09) | 0 (0) | 0.26 (0.12) | 0 (0) | −0.06 (0.03) | −0.08 | −0.04 | 0 (0) | 0 (0) |
| Other|| | 8 | 0.77 (0.62) | 4 (50) | 0.48 (0.37) | 1 (13) | 0.30 (0.65) | −0.31 | 1.41 | 2 (25) | 0 (0) |
| DM2 | 6 | 0.41 (0.25) | 2 (33) | 0.27 (0.11) | 0 (0) | 0.14 (0.24) | −0.06 | 0.60 | 1 (17) | 0 (0) |
| No Identified Mutation | 24 | 1.11 (1.64) | 9 (38) | 0.74 (0.89) | 3 (13) | 0.38 (1.65) | −1.44 | 7.11 | 5 (21) | 2 (8) |
N=number, SD = standard deviation, Min = minimum, Max = maximum, Upper = the 95% distribution upper bound, Lower = the 95% distribution lower bound.
Normal values were published in Logigian, E. L., C. L. Blood, et al. (2005). “Quantitative analysis of the “warm-up” phenomenon in myotonic dystrophy type 1.” Muscle Nerve 32(1): 35–42.
Recessive chloride channel mutations include: R105C+F167L+E624fs, c. 180+3A>T (+) 2434C>T p. ? (+) Gln812X, c. 180+3A>T (+) 568G>A p.? (+) Gly190Arg, E624fs, G285E, R894X.
Dominant chloride channel mutations include: A313T, G230E, F306L, R894X.
Inheritence unknown chloride channel mutations: R894X, c. 180+3A>T (+) 1283>C p. ? (+) F428S, V236L, G190R, F484L, F413C, I556N, M560T.
Other sodium channel mutations include: S804F, S1434P, L128P, V1293I, V1589M.