Generalised Bayesian analysis for autosomal recessive disease with two independent risk factors (scenario 2)*
| Variable | Generalised Bayesian analysis variables | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| *The fetus has been found to have one detectable mutation (heterozygous). One of the parents (Parent A) has been tested and no mutation is detected. The other parent (Parent B) has not been tested. | |||||||||
| Prior probabilities | |||||||||
| Parent A | |||||||||
| Carrier (Da+N) | x | ||||||||
| Non-carrier (N+N) | 1−x | ||||||||
| Test negative | 1−c | 1 | |||||||
| Parent B | |||||||||
| Carrier (Db+N) | y | y | |||||||
| Non-carrier (N+N) | 1−y | 1−y | |||||||
| Conditional probabilities | |||||||||
| Fetus | |||||||||
| Affected (Da+Db) | 0.25 | ||||||||
| Carrier (Da+N) | 0.25 | 0.5 | |||||||
| Carrier (Db+N) | 0.25 | 0.5 | |||||||
| Non-carrier (N+N) | 0.25 | 0.5 | 0.5 | 1 | |||||
| Risk factor number 1 (that is, echogenic bowel) | a | b | b | b′ | b | b′ | b | b′ | b′ |
| One mutation identified | |||||||||
| Db | f | f | f | ||||||
| Da | 0 | 0 | |||||||
| N | 0 | 0 | 0 | 0 | |||||
| No other mutation detected | |||||||||
| Da | 1 | ||||||||
| N | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | |
| Joint probability | 0.25xyaf (1−c) | 0 | 0.25xybf (1−c) | 0 | 0 | 0 | 0.5 (1−x) ybf | 0 | 0 |
| Column | A | B | C | D | E | F | G | H | I |