Table 1.
Demographic and clinical characteristics of MZ twins discordant for MS
| Characteristic | MZ twins |
| No. of pairs | 34 |
| Gender, female/male | 26/8 |
| Age in years (range in years) | 41.3 ± 10.8 (21–63) |
| Age in years at disease onset (range in years) | 28.0 ± 9.0 (14–47) |
| Time in years clinically discordant for MS (range in years) | 13.2 ± 9.6 (1–33) |
| Pairs clinically discordant for MS longer than 10 y (%) | 18 (53) |
| Pairs with a positive family history of MS (%) | 11 (32) |
| MS type, n (%) | |
| CIS | 3 (9) |
| RR-MS | 22 (65) |
| SP-MS | 7 (21) |
| PP-MS | 2 (6) |
| Disease-modifying treatment, n (%) | |
| Untreated | 15 (44) |
| IFN-β | 13 (38) |
| Natalizumab | 4 (12) |
| Glatiramer acetate | 1 (3) |
| Azathioprine | 1 (3) |
Continuous data are expressed as mean ± SD. Categorical data are expressed as the number of observations (%). CIS, clinically isolated syndrome; PP-MS, primary progressive MS; RR-MS, relapsing–remitting MS; SP-MS, secondary progressive MS.