Generalised Bayesian analysis for autosomal recessive disease with two independent risk factors (scenario 4)*
| Variable | Generalised Bayesian analysis variables | |||
|---|---|---|---|---|
| *Fetus has one detectable mutation (heterozygous). One of the parents (parent A) has the mutation detected in the fetus, but the other parent (parent B) tests negative. Note differences from table 6. | ||||
| Parent B | Carrier (Db+N) | Non-carrier | ||
| Prior probability | y | 1−y | ||
| Conditional probability of negative genetic test | 1−d | 1 | ||
| Conditional probabilities | ||||
| Fetus (affected or carrier) | ||||
| Affected (Da+Db) | 0.25 | |||
| Carrier (Da+N) | 0.25 | 0.5 | ||
| Carrier (Db+N) | 0.25 | |||
| Alleles | ||||
| From parent A | Da (detected) | Da (detected) | N (no mutation) | Da (detected) |
| From parent B | Db (undetected) | N (no mutation) | Db (detected) | N (no mutation) |
| 1 | 1 | 0 | 1 | |
| Risk factor number 1 (echogenic bowel) | a | b | b | b |
| Joint probability | 0.25ya(1−d) | 0.25yb(1−d) | 0 | 0.5(1−y)b |
| Column | A | B | C | D |