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TBX1 gene

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

TBX1 gene

The TBX1 gene provides instructions for a protein that acts as a transcription factor, playing a critical role in the development of the face, neck, heart, and ears.

Normal Function

The TBX1 gene provides instructions for making a protein called T-box protein 1. Genes in the T-box family play important roles in the formation of tissues and organs during embryonic development. Proteins produced from these genes bind to specific areas of DNA near genes to help control their activity; because of this action, T-box proteins are called transcription factors.

T-box protein 1 appears to be necessary for the normal development of muscles and bones of the face and neck, large arteries that carry blood out of the heart, structures in the ear, and glands such as the thymus and parathyroid.

Health Conditions Related to Genetic Changes

22q11.2 deletion syndrome

Most cases of 22q11.2 deletion syndrome are caused by a deletion of a small piece of chromosome 22 that contains 30 to 40 genes, including the TBX1 gene. In a small number of affected individuals without a chromosome 22 deletion, mutations in the TBX1 gene are thought to be responsible for the characteristic signs and symptoms of the syndrome.

These genetic changes likely affect the ability of T-box protein 1 to bind to DNA and regulate the activity of other genes. A reduction in the amount of T-box protein 1 or changes in the protein's normal function are associated with:

  • Heart defects
  • Cleft palate (an opening in the roof of the mouth)
  • Distinctive facial features
  • Hearing loss
  • Low calcium levels
  • Behavioral problems

Other Names for This Gene

  • CAFS
  • CTHM
  • DGCR
  • DGS
  • DORV
  • TBX1_HUMAN
  • TBX1C
  • Testis-specific T-box protein
  • TGA
  • VCFS

Frequently Asked Questions

The TBX1 protein acts as a transcription factor that regulates the expression of other genes required for the formation of the outflow tract of the heart. When TBX1 function is reduced or absent, the septum that divides the pulmonary artery and aorta may not form correctly. This often results in conotruncal heart defects such as tetralogy of Fallot, truncus arteriosus, or ventricular septal defects, which are common in 22q11.2 deletion syndrome.
Yes, although rare, some individuals have specific mutations or deletions within the TBX1 gene itself without the larger 22q11.2 chromosomal deletion. These isolated TBX1 mutations can cause a phenotype that overlaps significantly with 22q11.2 deletion syndrome, including heart defects, cleft palate, and distinctive facial features, because TBX1 is the primary driver of these developmental pathways.
TBX1 is essential for the proper development of the parathyroid glands, which regulate calcium levels in the body. When TBX1 function is impaired, the parathyroid glands may be underdeveloped or absent (hypoplasia or aplasia). This leads to hypoparathyroidism, a condition where the body cannot maintain adequate calcium levels, often requiring lifelong calcium and vitamin D supplementation.
Clinicians look for a specific pattern of associated symptoms. While cleft palate can occur in isolation, TBX1-related cases are typically part of a broader syndrome involving cardiac defects, immune system issues (due to thymic hypoplasia), and characteristic facial features such as a long face and hooded eyelids. Genetic testing for the 22q11.2 deletion or TBX1 sequence analysis is used to confirm the diagnosis when this specific constellation of symptoms is present.
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.