Inheriting Abnormal Autosomal Recessive Genes

A person who has one abnormal autosomal recessive gene for a disease is a carrier. That is, the person does not have the disease but can pass the abnormal gene to a son or daughter. If both parents are carriers of a gene for an autosomal recessive (non-X-linked) disease (one abnormal gene [black circles] and one normal gene [white circles]), they can pass it to their children. Each child has a 25% chance of inheriting two normal genes (ie, of being normal), a 50% chance of inheriting one normal and one abnormal gene (ie, of being a carrier), and a 25% chance of inheriting two abnormal genes (ie, of having the disease).