What Are Some Rare Medical Conditions?

The Office of Rare Diseases Research (a branch of the National Institutes of Health) classifies rare diseases as those that affect fewer than 200,000 Americans. Most rare diseases are hereditary, which means they can be passed down from a person’s parents, even if the parents are not themselves affected.


As the Genetics Home Reference explains, achondroplasia is a genetic problem affecting bone development. Patients with achondroplasia have a defect in turning cartilage into bone. This problem causes shorter than normal bones, particularly those of the limbs. Achondroplasia leads to short stature (average height of 131 centimeters for men, 124 centimeters for women). Patients typically have a normal-sized trunk and an unusually large head. Achondroplasia, according to the Genetics Home Reference, is the most common cause of short-limbed dwarfism and affects between one in 15,000 and one in 40,000 newborns.

Factor V Deficiency

As Medline explains, factor V deficiency is the result of a genetic disorder that results in problems with blood clotting. Factor V is a protein which has a central role in the signaling pathway needed to create blood clots. Patients with a factor V deficiency may have a genetic mutation that causes the body to produce low levels of factor V. Or they may have a genetic disorder that causes the factor V that is produced to be mutated and ineffective. They may also produce antibodies that bind to factor V, keeping it from being functional. Patients with this rare disorder are prone to easy bruising and bleeding.

Familial Adenomatous Polyposis

According to the American Society of Clinical Oncology, somewhere between one in 7,000 and one in 22,000 people have familial adenomatous polyposis. This genetic condition causes patients to develop a multitude of polyps (small outgrowths) within the colon. Most patients have extensive colon polyps by the age of 35. This condition causes a severe increase in the risk of the patient developing colon cancer; the American Society of Clinical Oncology notes that 87 percent of patients with this disease who are not treated develop colon cancer by the age of 45. Colon cancer caused by familial adenomatous polyposis can be prevented by surgical removal of the colon.

About this Author

Adam Cloe has been published in various scientific journals. He is an M.D./Ph.D. student at the University of Chicago. He has a Bachelor of Arts in biochemistry from Boston University, where he won an award for excellence in undergraduate science writing.