Table 1. Loss or gain of methylation (LOM or GOM, respectively: >10% difference from median).
| H19-ICR (%) | IGF2-DMR (%) | KvDMR (%) | NESPAS-ICR (%) | RUNX1 (%) | ||
| MZ | concordant for LOM | 60 (2.0) | 74 (4.3) | 0 (0.0) | 22 (0.8) | 56 (1.8) |
| discordant for LOM | 265 (9.0) | 192 (11.1) | 52 (1.9) | 17 (0.6) | 72 (2.3) | |
| no LOM | 2612 (88.9) | 1464 (84.6) | 2672 (98.1) | 2720 (98.6) | 3047 (96.0) | |
| DZ | concordant for LOM | 38 (1.3) | 60 (3.5) | 0 (0.0) | 0 (0.0) | 56 (1.7) |
| discordant for LOM | 268 (9.0) | 195 (11.4) | 20 (0.7) | 17 (0.6) | 72 (2.2) | |
| no LOM | 2665 (89.7) | 1459 (85.1) | 2735 (99.3) | 2732 (99.4) | 3106 (96.0) | |
| chi-square test LOM | P <0.01 | ns | P <0.001 | P <0.001 | ns | |
| MZ | concordant for GOM | 110 (3.7%) | 24 (1.4%) | 0 (0.0%) | 0 (0.0%) | 4 (0.1%) |
| discordant for GOM | 329 (11.2%) | 174 (10.1%) | 30 (1.1%) | 32 (1.2%) | 85 (2.7%) | |
| no GOM | 2498 (85.1%) | 1532 (88.6%) | 2694 (98.9%) | 2727 (98.8%) | 3086 (97.2%) | |
| DZ | concordant for GOM | 110 (3.7%) | 24 (1.4%) | 0 (0.0%) | 0 (0.0%) | 4 (0.1%) |
| discordant for GOM | 329 (11.1%) | 174 (10.2%) | 22 (0.8%) | 32 (1.2%) | 85 (2.6%) | |
| no GOM | 2532 (85.2%) | 1516 (88.4%) | 2733 (99.2%) | 2717 (98.8%) | 3145 (97.2%) | |
| chi-square test GOM | ns | ns | ns | ns | ns | |
Number (and percentage) of observations are displayed in the relevant groups. The chi-square test (3×2; df = 2) was performed to test for significant differences between MZ and DZ twins (see Table S2 for other cut-off values for loss or gain of methylation).