For a disease that causes from recessive allele, it needed two copies of the same gene, like if both parents are the carriers for sickle cell anemia, the child will inherit it. Meanwhile, different from recessive allele, a child with dominant allele disorder causes by only one abnormal gene, by one of the parents.
Cystic fibrosis (CF) is caused by a recessive allele. You need to inherit two copies of the faulty allele to have CF. If you just have one copy of the faulty allele, you are a carrier but have no symptoms.If two carriers have a child between them, there is aone in fourchance of that child having the disorder.
An example of a dominant single genedisorder isHuntington’s disease,which is a disease of the nervous system.