Fig. 3.

Power of the test based on sharing probabilities. Power was computed for a dominant RV with frequency of $1\times {10}^{-4}$. The disease had a population prevalence of 1% and a recurrence risk to offspring of 5, to first cousins of 2 and to second cousins of 1.25. The significance level of $2.1\times {10}^{-5}$ was achieved when 10/10 parent–offspring pairs, 4/4 or 6/10 first cousins pairs and 3/4 or 4/10 second cousin pairs shared the RV (4 parent–offspring pairs are insufficient to achieve the significance level)