Observed and Expected Numbers of 0–0 and 1–1 Symmetrical Class 1 and Class 2 Domains inC. elegans [i]
| Category | Comb. | Obs. | Exp. | P |
| Class 1 domains | ||||
| Domain (83) | 0–0 | 13 | 8.7 | 0.13 |
| 1–1 | 36 | 25.5 | <0.05 | |
| 2–2 | 2 | 1.2 | n.d. | |
| 51 | 35.4 | <10−3 | ||
| Domain family (41) | 0–0 | 9.9 | 8.5 | 0.59 |
| 1–1 | 10.7 | 6.1 | <0.05 | |
| 2–2 | 0.8 | 0.9 | n.d. | |
| 21.4 | 15.5 | 0.06 | ||
| Class 2 domains | ||||
| Domain (81) | 0–0 | 13 | 7.1 | <0.05 |
| 1–1 | 21 | 17.5 | <0.34 | |
| 2–2 | 5 | 4.3 | n.d. | |
| 39 | 28.9 | <0.05 | ||
| Domain family (47) | 0–0 | 8.3 | 4.7 | 0.11 |
| 1–1 | 10.7 | 8.4 | 0.38 | |
| 2–2 | 4.3 | 3.2 | n.d. | |
| 23.3 | 16.3 | <0.05 |
[i] Total numbers of domains in each category are indicated in parentheses. Summed combinations of symmetrical domains are shown in boldface. Note that only class 2 domains encoded by 2 exons are considered here (see text for details). (Comb.) Combinations; (Obs.) observed; (Exp.) expected.