Table 2.
Estimate of Type-Specific Mutation Rates based on Factor IX Coding Sequences
| Mutation Type | Target Size (x)a | No. of Independent Mutations (y)b | Estimated MutationRatec (× 1010) |
| Transitions: | |||
| CpG | 20 | 76 | μ1 = 973 |
| Non-CpG | 281.2 | 80 | μ2 = 72.8 |
| Transversions: | |||
| All | 523.6 | 70 | μ3 = 68.4 |
| Non-CpG | 485.6 | 66 | μu = 69.6 |
| CpG | 38 | 4 | μv = 53.9 |
| All base substitutions | 824.8 | 226 | μ4 = 210 |
| Small deletions/insertions causing frameshifts | 1,362 | 17 | μ5 = 3.19 |
| All above types | μ6 = 213 |
a
No. of different base substitutions expected to cause hemophilia B or of positions where frameshift mutations may occur through small deletions/insertions.
b
Observed in the factor IX coding sequence of hemophilia B patients from the United Kingdom.
c
The formula used for estimation is niμyi/txi=μi (see text). μ = 7.733 × 10−6; t = 302; i = 1, 2, 3, 4, 5, 6, u, or v. Note that μi is expressed per base per generation and that μ and t have been determined in the accompanying article (Green et al. 1999 [in this issue]).