Observed and Expected Numbers of Symmetrical Nonboundary Exons or Sets of Nonboundary Exons
| No. of exons | Comb. | Obs. | Exp. | P |
| 1 exon (2007) | 0–0 | 508 | 533 | 0.21 |
| 1–1 | 154 | 139.7 | 0.21 | |
| 2–2 | 96 | 97.6 | 0.87 | |
|
758 | 770.3 | 0.57 | |
| 2 exons (842) | 0–0 | 243 | 252.9 | 0.46 |
| 1–1 | 59 | 55.2 | 0.6 | |
| 2–2 | 27 | 32.3 | 0.34 | |
|
329 | 340.4 | 0.42 | |
| 3 exons (454) | 0–0 | 121 | 130 | 0.35 |
| 1–1 | 30 | 32.2 | 0.69 | |
| 2–2 | 16 | 17.1 | 0.79 | |
|
167 | 179.3 | 0.24 | |
| 4 exons (301) | 0–0 | 95 | 92.4 | 0.75 |
| 1–1 | 26 | 20.5 | 0.21 | |
| 2–2 | 5 | 10 | 0.11 | |
|
126 | 122.9 | 0.72 | |
| 5 exons (187) | 0–0 | 52 | 53.9 | 0.76 |
| 1–1 | 22 | 17 | 0.2 | |
| 2–2 | 4 | 4.8 | n.d. | |
|
78 | 75.7 | 0.73 | |
| 6 exons (118) | 0–0 | 37 | 36.8 | 0.97 |
| 1–1 | 14 | 11.6 | 0.46 | |
| 2–2 | 1 | 1.9 | n.d. | |
|
52 | 50.3 | 0.75 |
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↵The total number of cases in each group are indicated in parentheses. The expected values were calculated based on the phase frequencies of flanking introns (see Methods). Summed symmetrical combinations are shown in boldface. Some P-values were not determined (n.d.) due to the low sample size.
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↵Combination of flanking intron phases.
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↵Observed.
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↵Expected.











