Table 5.
Comparison of the observed and expected number of mothers with multiple contractions of premutation alleles
| Multiple contractions (n contractions/n transmissions) | 2/2 | 2/3 | 3/4 | |
|---|---|---|---|---|
| Repeat structure in 4 mothers | 10A68, 9A69 | 79 | 83 | |
| Likelihood of observed contractions | p 2 | 3*p 2*(1 − p) | 4*p 3*(1 − p) | |
| Estimated likelihood assuming independence of events (p = .0508 or .0737a) | 0.003, 0.006 | 0.007, 0.015 | 0.0005, 0.002 | |
| Number of mothers with 2, 3, or 4 transmissions | 85 | 15 | 5 | |
| Expected number of mothers with multiple contractions (p = .0508, .0737) | 0.22, 0.47 | 0.11, 0.23 | 0.002, 0.01 | |
| Observed number of mothers with multiple contractions | 2 | 1 | 1 | |
a
0.0508 is the empirical estimate of the frequency of repeat contractions based on mothers having only one transmission (see text); 0.0737 is the upper limit of the 95% confidence interval of this estimate.