Cystic fibrosis is a genetic disorder of the cell membranes. It results in the body producing a lot of thick, sticky mucus in the air passages and in the pancreas.
- The allele which causes cystic fibrosis is a recessive allele, carried by 1 in 25 people
- Because its recessive, people with only one copy of the allele won't have the dosorder - they're known as carriers.
- For a child to have the disorder, both parents must be either carriers or sufferers.
Polydactyly is a genetic disorder where a baby's born with extra fingers or toes. It doesn't usually cause any other problems so it isn't 'life-threatening'.
- The disorder is caused by a dominant allele, and so can be inherrited if just one parent carries the defective allele.
- The parent that has the defective allele will…