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TBP gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

TBP gene

The TBP gene provides instructions for the TATA-box binding protein, which is essential for regulating the activity of most genes in the body.

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, including uncontrolled movements, emotional problems, and a loss of thinking ability. HDL4 is sometimes known as spinocerebellar ataxia 17 (SCA17).

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. An increased number of repeats leads to the production of an abnormally long version of the TATA-box binding protein, which builds up in nerve cells (neurons) in the brain and disrupts their normal functions.

Other Names for This Gene

  • GTF2D
  • TAF2A
  • TAFII250
  • TATA-Box Factor
  • TBP_HUMAN
  • TF2D
  • TFIID

Frequently Asked Questions

Diagnosis of HDL4/SCA17 is primarily confirmed through genetic testing. This test analyzes the TBP gene to identify an abnormal expansion of the CAG/CAA trinucleotide repeat segment. A repeat count significantly higher than the normal range (typically 25-40 repeats) indicates the presence of the condition. Clinical evaluation of symptoms and family history also play a crucial role in the diagnostic process.
HDL4/SCA17 is characterized by a range of neurological symptoms that often resemble Huntington's disease. These include involuntary movements (chorea), problems with coordination and balance (ataxia), difficulties with speech (dysarthria), and swallowing (dysphagia). Cognitive decline, such as memory loss and impaired judgment, as well as psychiatric symptoms like depression, anxiety, and personality changes, are also common. Symptoms typically progress slowly over many years.
There is currently no cure for HDL4/SCA17, so treatment focuses on managing symptoms and improving quality of life. Medications can help control involuntary movements, psychiatric symptoms, and other neurological issues. Physical therapy, occupational therapy, and speech therapy are vital for maintaining mobility, independence, and communication skills. Supportive care, including nutritional support and psychological counseling, is also important.
HDL4/SCA17 is inherited in an autosomal dominant pattern. This means that only one copy of the expanded TBP gene is needed to cause the disorder. Therefore, if a parent has HDL4/SCA17, there is a 50% chance with each pregnancy that their child will inherit the expanded gene and develop the condition. Genetic counseling is highly recommended for affected individuals and their families to understand inheritance patterns and reproductive options.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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