Virtually all diseases involve genetic factors to some extent. Diseases that appear to result from simple mutations of single genes are often referred to as hereditary diseases, and they exhibit distinctive patterns of inheritance in families. There are approximately 6000 genetic diseases presently known.

Autosomal dominant genetic diseases are passed along from parent to child with an equal chance for sons and daughters to get the disease. This is sometimes referred to as vertical transmission because it is seen in each generation, usually without skipping. Normally there are two working copies of every gene in each individual. In the case of a dominant genetic disease, one copy of the gene is altered by mutation and the other copy is normal. The inheritance pattern seen in autosomal dominant diseases is that parents who show the trait pass the mutation on to half of their children. Children who do...