Generalised Bayesian analysis for autosomal recessive disease with two independent risk factors (scenario 3)*
| Variable | Generalised Bayesian analysis variables | |||
|---|---|---|---|---|
| *Fetus found to have one detectable mutation (heterozygous). One of the parents (parent A) has the mutation detected in the fetus, but the other parent (parent B) not tested. | ||||
| Prior probability for parent B | ||||
| Carrier (Db+N) | y | |||
| Non-carrier | 1−y | |||
| Conditional probabilities | ||||
| Fetus (affected or carrier) | ||||
| Affected (Da+Db) | 0.25 | |||
| Carrier (Da+N) | 0.25 | 0.5 | ||
| Carrier (Db+N) | 0.25 | |||
| Allele | ||||
| From parent A | Da (detected) | Da (detected) | N (no mutation) | Da (detected) |
| From parent B | Db (undetected) | N (no mutation) | Db (detected and the same as Da) | N (no mutation) |
| 1−d | 1 | f | 1 | |
| Risk factor number 1 (that is, echogenic bowel) | a | b | b | b |
| Joint probability | 0.25ya(1−d) | 0.25yb | 0.25ybf | 0.5(1−y)b |
| Column | A | B | C | D |