by Kimberly Allen, RN
Tangier disease is a very rare genetic disorder that was first discovered in 1961. It gets it’s name from the island off the coast of Virginia named Tangier island where it was discovered in a young boy and his sister. Though it was first diagnosed on Tangier island it has since been seen in other states as well as other countries.
Tangier disease is an autosomal recessive genetic disorder, meaning you need to receive a copy of the defective gene from each parent. In Tangier disease, the mutation occurs in the ABCA1, also known as ATP-Binding Cassette transporter A1, gene on chromosome 9. The ABCA1 gene carries the instructions for producing a protein that is responsible for releasing excess cholesterol as well as phospholipoids from your cells. The cholesterol and phospholipoids are used to produce the high density lipoprotein or HDL, which is known as the “good” cholesterol. The HDL then transports them to the liver. Mutations in this gene prevents the cholesterol and phospholipoids from being released from your cells. This not only leads to very low levels of HDL in your bloodstream but causes the cholesterol and phospholipoids to accumulate in your cells. The build up of excess cholesterol and phospholipoids in your cells causes them to swell which in turn leads to malfunction and/or death of the cell. Because your body is unable to transport the excess cholesterol and phospholipoids out of the cells to produce HDL there are very low levels of HDL in your bloodstream which also increases your chances of developing cardiovascular disease.
The symptoms of Tangier disease can vary from mild to severe. They usually manifest in childhood. Some people have mutations in both copies of their ABCA1 gene which can cause more severe symptoms. Most people with Tangier disease experience a range of neurological problems including peripheral neuropathy, which is damage to your peripheral nerves. Many also experience the loss of sensation for pain or heat as well as muscle pain and reduced strength. Because the excess cholesterol and phospholipoids accumulate in your cells there are excess fat deposits in certain tissues like your cornea and conjunctiva. This causes the cornea to become cloudy and can lead to vision loss. Some people with Tangier disease also experience abdominal cramping and diarrhea due to the accumulation of cholesterol and phospholipoids in the intestinal mucosa. Probably the most well know symptom and the one that lead to the discovery of Tangier disease is the appearance of enlarged tonsils that are yellowish orange in color. As the disease progresses the accumulation of cholesterol and phospholipoids in the cells causes certain organs like the liver and spleen to become enlarged. And of course it also leads to premature cardiovascular disease which brings with it all the symptoms associated with it.
People that are born with one copy of the mutated ABCA1 gene have approximately half the normal amount of HDL circulating in their bloodstream therefore they tend to experience either very mild symptoms or no symptoms at all. However, because their HDL levels are so low they are still at risk for developing pass the disease on to their children.
Though there is no cure for Tangier disease currently available treatment varies from person to person depending on the severity of the disease and your symptoms. However, the discovery of the gene that causes Tangier disease has lead to a much better understanding of how LDL works leading to the development of more effective medications to treat high levels of LDL levels. There is also research into therapies that could increase HDL levels reducing the risk of cardiovascular disease. This research has also increased researchers knowledge in the diagnosis and treatment of heart disease.
Kimberly Allen is a registered nurse with an AND in nursing. She has worked in ACF, LCF and psychiatric facilities, although she spent most of her career as a home health expert. She is now a regular contributor to HealthAndFitnessTalk.com, dispensing advice and knowledge about medical issues and questions. You can reach her with any comments or questions at firstname.lastname@example.org.