Tangier disease is an unusual genetic disorder involving the gene that codes for successful transport of high density lipoprotein (HDL) out of body tissue and into the bloodstream. Patients with this disorder have very low levels of HDL in their bloodstreams and experience buildups of cholesterol in their organs and other tissues. This can lead to health problems later in life. It cannot be cured, but people can take some steps to manage it.
This condition was identified in the 1960s on an island off the US state of Virginia. In the 1990s, a gene responsible for Tangier disease was identified, demonstrating that it was an error of cholesterol transport. Patients are usually diagnosed with this condition in late childhood or early adulthood. A blood test will show low levels of HDL and high levels of fats, as HDL normally transports fat out of the bloodstream. In addition, the patient may have enlarged organs showing fatty deposits.
Patients with Tangier disease typically experience neuropathy, a disorder of nerve function, as a result of the imbalance of cholesterol in the body. This can lead to numbness, tingling, and other problems associated with malfunctioning nerves. Over time, the enlargement of organs can lead to other health problems like a breakdown in liver function. The high levels of fat in the bloodstream can become contributors to cardiovascular disease, putting patients at risk of conditions like heart attack and stroke.
This lipoprotein deficiency is recessive. People must inherit both copies of the gene involved in order to develop Tangier disease. In other cases, people will be carriers with the potential to pass the gene on to their children. People with a family history of Tangier disease can request testing to see if they have the gene and may consider this when preparing to have children, especially if their partners also have the gene or the condition itself.
Researchers interested in genetic diseases are considering the application of a number of techniques to their treatment. In the short term, measures designed to address the symptoms are the primary approach to management, but in the future, options like gene therapy may be possible. In gene therapy, defective genes could be overridden or turned off with therapy administered after birth; in this case, a gene to correctly transport HDL could be inserted so patients would start expressing it, carrying the HDL deposits out of the body's tissues and into the bloodstream.
