Normal Function
The TBP gene provides instructions for making a protein called the TATA-box binding protein. This protein is active in cells and tissues throughout the body, where it plays an essential role in regulating the activity of most genes.
The TATA-box binding protein attaches (binds) to a particular sequence of DNA known as the TATA box. This sequence occurs in a regulatory region of DNA near the beginning of many genes. Once the protein is attached to the TATA box near a gene, it acts as a landmark to indicate where other enzymes should start reading the gene. The process of reading a gene's DNA and transferring the information to a similar molecule called messenger RNA (mRNA) is known as transcription.
One region of the TBP gene contains a particular DNA segment known as a CAG/CAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (nucleotides) that appear multiple times in a row. Normally, the CAG/CAA segment is repeated 25 to 40 times within the gene.
Health Conditions Related to Genetic Changes
Huntington's disease-like
A particular type of variant (also called a mutation) in the TBP gene has been found to cause a condition called Huntington's disease-like 4 (HDL4). The signs and symptoms of HDL4 closely resemble those of a more common condition called Huntington's disease. These signs and symptoms include uncontrolled movements, emotional problems, and a loss of thinking ability. HDL4 is sometimes known as spinocerebellar ataxia 17 (SCA17). This diagnosis is typically used when the main signs and symptoms involve difficulties with coordination and movement.
The variants associated with HDL4 and SCA17 increase the size of the CAG/CAA trinucleotide repeat in the TBP gene. Generally, individuals with 41 or more CAG/CAA repeats can develop features of HDL4 or SCA17 in their lifetimes. People with larger repeats are more likely to develop signs and symptoms of these disorders.
An increased number of CAG/CAA repeats in the TBP gene leads to the production of an abnormally long version of the TATA-box binding protein. The abnormal protein builds up in nerve cells (neurons) in the brain and disrupts the normal functions of these cells. The dysfunction and eventual death of neurons in certain areas of the brain cause the signs and symptoms of HDL4 and SCA17. Because the TBP gene is active throughout the body, it is unclear why the effects of variants in this gene are limited to the brain.
More About This Health ConditionOther Names for This Gene
- GTF2D
- TAF2A
- TAFII250
- TATA-Box Factor
- TBP_HUMAN
- TF2D
- TFIID
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
References
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- Schneider SA, van de Warrenburg BP, Hughes TD, Davis M, Sweeney M, Wood N, Quinn NP, Bhatia KP. Phenotypic homogeneity of the Huntington disease-like presentation in a SCA17 family. Neurology. 2006 Nov 14;67(9):1701-3. doi: 10.1212/01.wnl.0000242740.01273.00. Citation on PubMed
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- Zuhlke C, Hellenbroich Y, Dalski A, Kononowa N, Hagenah J, Vieregge P, Riess O, Klein C, Schwinger E. Different types of repeat expansion in the TATA-binding protein gene are associated with a new form of inherited ataxia. Eur J Hum Genet. 2001 Mar;9(3):160-4. doi: 10.1038/sj.ejhg.5200617. Citation on PubMed
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