Approximately 4500 different diseases are known to be caused by a defect in a single gene. As a group, these disorders are called monogenic, or mendelian, diseases. They most often show 1 of 3 patterns of inheritance: autosomal dominant, autosomal recessive, or X-linked. Disorders of mitochondrial DNA are inherited in a fourth manner, termed maternal inheritance.
Excerpted from BCSC 2020-2021 series: Section 2 - Fundamentals and Principles of Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.