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McDonald-Kreitman Tests of Neutrality
| Samplea | Silent | Replacement | Fisher's Exact Test |
| Africans (n=160): | |||
| Polymorphic | 22 | 3 | P<.05 |
| Fixed | 44 | 0 | |
| Non-Africans (n=56): | |||
| Polymorphic | 8 | 4 | P<.001 |
| Fixed | 44 | 0 | |
| Global (n=216): | |||
| Polymorphic | 23 | 5 | P<.01 |
| Fixed | 44 | 0 |
Numbers of polymorphisms and fixed differences found at both silent and replacement (i.e., those that change the amino acid) sites are contrasted with a 2×2 Fisher's exact test of independence (see the “Subjects and Methods” section).
