Genetic Disorders

If one parent has an autosomal dominant disease, then offspring have a 50% chance of inheriting that disease. There are roughly 2000 autosomal dominant disorders (ADDs) with effects that range from mild clinical manifestations to death. These diseases may develop early or late in life. ADDs include Huntington disease, Marfan syndrome (extra long limbs), achondroplasia (a type of dwarfism), some forms of glaucoma, most forms of porphyrias, and hypercholesterolemia (high blood cholesterol).

Huntington Disease is a late onset nuerodegenerative disease. It is characterized by progressive chorea (involuntary, rapid, jerky motions) and mental deterioration that often develop after the fourth decade of life, eventually leading to death approximately 15 years later. The Huntington disease gene locus is on chromosome 4, and can be identified.

Marfan syndrome is an ADD characterized by long arms, legs, and fingers. People with Marfan syndrome also have a blue sclera that represents a hallmark clinical feature that can be detected when observing the eyes. In addition, these individuals have a high incidence of eye and aortic heart problems. The elasticity of the vessels in the aorta are susceptible to rupture, which can cause death. Not all people with Marfan syndrome inherit it from a parent, about 15% of Marfan syndrome cases are caused by a spontaneous mutation.