TTR gene
The TTR gene provides instructions for making the protein transthyretin, which transports vitamin A and thyroxine throughout the body.
Normal Function
The TTR gene provides instructions for making a protein called transthyretin. This protein transports vitamin A (retinol) and a hormone called thyroxine throughout the body. To transport thyroxine, four transthyretin proteins must attach to each other to form a unit called a tetramer. To transport retinol, transthyretin must form a tetramer and bind to another protein called retinol-binding protein. Transthyretin is produced primarily in the liver, with small amounts produced in the brain (choroid plexus) and the retina of the eye.
Health Conditions Related to Genetic Changes
Transthyretin amyloidosis
Variants in the TTR gene cause transthyretin amyloidosis. These variants alter the structure of transthyretin, impairing its ability to form tetramers. The tetramers break down into individual proteins that attach to each other to form strands called fibrils. These fibrils clump together to form amyloid deposits in certain tissues, leading to the condition's symptoms.
- Val50Met (V50M): The most common variant, seen frequently in Portuguese and Swedish populations.
- Val142Ile (V142I): A variant estimated to be present in 3 to 3.9 percent of African Americans and 5 percent of some West African populations.
Senile systemic amyloidosis
In some older adults, deposits of normal transthyretin proteins cause senile systemic amyloidosis. These individuals do not have a TTR gene variant. The condition most commonly affects the heart, causing progressive heart failure, but may also affect the lungs, blood vessels, and kidneys. It is estimated that 10 to 25 percent of people older than 80 have this condition.
Other Names for This Gene
- ATTR
- PALB
- prealbumin, amyloidosis type I
- TBPA
- TTHY_HUMAN
