What is Transthyretin?

Transthyretin is a protein produced in the liver for the purpose of carrying chemical compounds used in cell metabolism throughout the body. It is among a class of proteins known as alpha globulins and used to be called prealbumin. The gene responsible for encoding this protein is located on the 18th chromosome and is known as the TTR gene. Mutations in this gene can lead to health problems as they force the liver to make a variant version of transthyretin.

Two different compounds are carried by transthyretin: retinol and a thyroid hormone called thyroxine. Cells throughout the body use these products in metabolism. In healthy individuals, production of transthyretin tends to remain fairly constant, except when people experience inflammation and malnutrition, both of which can cause levels to drop. Blood levels of transthyretin can be checked in the lab and may be used in diagnostic testing of patients with suspected health problems.

When the TTR gene is mutated, people can develop a condition called amyloidosis, where deposits of protein build up in the body. In healthy individuals, proteins like transthyretin are broken down and recycled by the body, without having a chance to accumulate. When the protein is mutated, however, the body may have difficulty processing it, and plaques may start to form in various organs and in the peripheral nervous system. Amyloidosis is a genetic disease and cannot be cured, but liver transplant can be beneficial for some patients, by providing the patient with a liver that will stop making the defective protein.

Deposition of amyloid plaques is also associated with some conditions like Alzheimer's disease. Transthyretin can easily cross the blood-brain body and it travels in the cerebrospinal fluid, as well as the blood. In people with disorders leading to buildups of this protein, it can create brain lesions leading to cognitive impairments. These lesions are sometimes visible on medical imaging studies and in other cases may only be identified during autopsy.

People with a family history of conditions involving the TTR gene may want to be aware that their bodies could be producing a mutated version of transthyretin, and they may be at risk for the development of disease as a result. Regular clinical evaluations can be used to check for early signs of damage to the nerves and organs, allowing doctors to intervene as quickly as possible in patients who are not producing a normal version of the protein.