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TBX19
T-box transcription factor 19
TBX19 is located on the long (q) arm of chromosome 1, at band 1q24.2. Arm ratio per GRCh38 - banding schematic.
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Overview
TBX19 encodes T-box transcription factor 19, a protein belonging to the T-box family of DNA-binding transcription factors. These proteins share a highly conserved DNA-binding domain and regulate developmental processes across multiple organ systems. TBX19 is specifically expressed in the anterior pituitary gland, where it directs the differentiation and maintenance of corticotroph cells.
Corticotrophs produce adrenocorticotropic hormone, which stimulates the adrenal glands to release cortisol. Cortisol is essential for various physiological processes. Without functional TBX19, corticotroph development is impaired, leading to insufficient ACTH production and subsequent cortisol deficiency.
What the gene does
The TBX19 protein functions as a transcription factor, meaning it binds to specific DNA sequences in the regulatory regions of target genes to control their expression. Within corticotroph cells of the anterior pituitary, TBX19 activates genes required for cell differentiation, survival, and hormone production. Research suggests that TBX19 works in coordination with other transcription factors to establish and maintain the corticotroph cell lineage during embryonic development and throughout life.
Loss of TBX19 function typically results in a selective deficiency of ACTH, while other pituitary hormones generally remain unaffected, highlighting the protein's highly specialised role in the pituitary gland.
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Chromosome location
TBX19 is located on chromosome 1 at cytogenetic band 1q24.2. This region of chromosome 1 contains numerous genes involved in developmental regulation and metabolic processes. The precise number of exons and detailed structural features of the TBX19 gene have been characterised through genomic sequencing, though specific structural annotations vary across databases.
Protein structure
Domain architecture has not been experimentally characterised in detail for this protein. TBX19 is classified within the T-box transcription factor family based on sequence homology, and members of this family typically possess a conserved T-box domain responsible for sequence-specific DNA binding. This domain generally spans approximately 180-200 amino acids and adopts a structure that recognises specific DNA motifs in target gene promoters.
Key variants
Genetic variants in TBX19 range from single nucleotide changes to small deletions or insertions. Pathogenic variants typically disrupt the protein's ability to bind DNA or activate target genes, impairing corticotroph development. The inheritance pattern for TBX19-related conditions can vary depending on the specific variant and its functional impact.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.158_159del | p.Arg53fs | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.535C>T | p.Arg179Ter | Pathogenic | ★★☆☆ | not provided |
c.627C>G | p.Tyr209Ter | Pathogenic | ★★☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.688G>T | p.Glu230Ter | Pathogenic | ★★☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.727+1G>A | - | Pathogenic/Likely pathogenic | ★★☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.782del | p.Asn261fs | Pathogenic | ★★☆☆ | TBX19-related disorder |
c.856C>T | p.Arg286Ter | Pathogenic | ★★☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.665+1G>T | - | Pathogenic | ★☆☆☆ | Congenital isolated adrenocorticotropic hormone deficiency |
c.829_830del | p.His277fs | Pathogenic | ★☆☆☆ | not provided |
c.82C>T | p.Gln28Ter | Pathogenic | ★☆☆☆ | TBX19-related disorder |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
Variants in TBX19 are associated with isolated adrenocorticotropic hormone deficiency, a condition characterised by insufficient ACTH production leading to low cortisol levels. Affected individuals may present in infancy or early childhood with clinical features related to cortisol deficiency. Because cortisol is essential for survival during physiological stress, untreated ACTH deficiency can lead to serious complications. The condition is typically managed through cortisol replacement therapy, which must be carefully monitored and adjusted throughout life.
No disease links recorded for this gene in our reference set.
UK clinical status
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the TBX19 gene do?
TBX19 produces a transcription factor that regulates gene expression in pituitary corticotroph cells. These cells produce adrenocorticotropic hormone, which signals the adrenal glands to release cortisol, a hormone essential for various physiological processes.
How are TBX19 variants inherited?
Inheritance patterns for TBX19-related conditions can vary depending on the specific genetic variant. Genetic counselling can help clarify inheritance risk for specific families based on the particular variant identified and family history.
Can TBX19 variants affect other pituitary hormones?
TBX19 variants typically cause isolated ACTH deficiency, meaning other pituitary hormones such as growth hormone, thyroid-stimulating hormone, and luteinising hormone generally remain at normal levels. This specificity reflects TBX19's dedicated role in corticotroph cell development.