In an autosomal dominant inheritance pattern, both women and men can inherit a disease gene equally. Every person has two copies of each gene. In an autosomal dominant condition, a person only needs to have one copy of the disease gene to be at increased risk for a particular disease. This is often inherited from an affected parent.

Reduced penetrance means if someone has a disease gene they are at a higher risk for developing the disease, but it does not mean they are absolutely going to be affected by it. The chance they will develop disease is less than 100%. Often, in diseases with reduced penetrance, environmental factors play a role in the development of disease.