When we know that a change or mutation in specific gene causes a condition, this condition is called a single gene condition. There are many single gene conditions, but some of the most common include cystic fibrosis, sickle cell anemia and Fragile X-associated disorders.

There are different ways that single gene conditions can be passed on in a family, which is called the condition’s pattern of inheritance. Some single gene conditions, such as cystic fibrosis and sickle cell anemia, follow an autosomal recessive pattern of inheritance, others are autosomal dominant and lastly, they may be X-linked.

For more information on specific single gene conditions, see the side bar.