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LTBP3
latent transforming growth factor beta binding protein 3
LTBP3 is located on the long (q) arm of chromosome 11, at band 11q13.1. Arm ratio per GRCh38 - banding schematic.
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Overview
LTBP3 (latent transforming growth factor beta binding protein 3) is located on chromosome 11 at band q13.1 and produces a protein of 1,303 amino acids. The protein functions as a regulator of TGF-beta, a growth factor that influences cell division, differentiation, and the formation of extracellular matrix throughout the body.
Pathogenic changes in LTBP3 follow an autosomal recessive inheritance pattern, meaning both gene copies must carry variants for disease to manifest. These variants disrupt normal skeletal development and tooth enamel formation. The gene is included in several NHS Genomic Medicine Service panels covering skeletal dysplasia, amelogenesis imperfecta, and foetal anomalies, reflecting its clinical importance in developmental disorders.
What the gene does
The LTBP3 protein acts as a molecular chaperone and regulator for transforming growth factor beta. It binds to the inactive (latent) form of TGF-beta and anchors it within the extracellular matrix, the scaffold of proteins and carbohydrates that surrounds cells. This anchoring maintains a reservoir of TGF-beta that can be released when needed for tissue remodelling and repair.
LTBP3 participates in the assembly of large latent TGF-beta complexes, which prevents premature activation of the growth factor. When cells require TGF-beta signalling, proteolytic enzymes or mechanical forces release the active growth factor from the complex. This controlled release mechanism ensures that TGF-beta signalling occurs at the appropriate time and location, which is particularly important during skeletal development and tooth formation. The protein's ability to sequester and present TGF-beta influences bone mineralisation, cartilage formation, and the deposition of dental enamel.
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Chromosome location
LTBP3 is located on the long arm of chromosome 11 at cytogenetic band q13.1. This chromosomal region contains multiple genes involved in developmental processes. The gene's position places it within a genomically stable area, though the specific number of exons and detailed structural organisation have not been fully characterised in all clinical references.
Protein structure
The LTBP3 protein comprises 1,303 amino acids organised into a modular architecture of repeating domains. The structure includes ten EGF-like domains distributed along the protein length, seven of which are calcium-binding (EGF-like 2, 4, 5, 6, 7, 8, 9, and 10). These calcium-binding modules typically stabilise protein structure and mediate interactions with other extracellular matrix components.
Three TB (TGF-beta binding) domains are present: TB 1 spanning amino acids 277-331, TB 2 from 403-455, and TB 3 from 917-971. These domains are responsible for capturing and retaining latent TGF-beta complexes. The protein also contains disordered regions between amino acids 247-282 and 478-552, which may provide structural flexibility needed for conformational changes during TGF-beta release. The arrangement of EGF-like and TB domains creates a framework that can both bind growth factors and integrate into the extracellular matrix meshwork.
Key variants
Pathogenic variants in LTBP3 typically result in loss of protein function, disrupting the normal storage and release of TGF-beta in developing tissues. These variants follow autosomal recessive inheritance, so individuals must inherit altered copies from both parents to develop clinical features. The specific effects of variants depend on their impact on protein stability, TGF-beta binding capacity, or incorporation into the extracellular matrix.
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.132del | p.Pro45fs | Pathogenic | ★★☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.3574G>T | p.Glu1192Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Geleophysic dysplasia 1 |
c.3605_3623dup | p.Arg1209fs | Pathogenic/Likely pathogenic | ★★☆☆ | LTBP3-related disorder |
c.1121del | p.Pro374fs | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.1383C>G | p.Tyr461Ter | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.1626del | p.Ile543fs | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.3418_3419del | p.Ser1140fs | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.3646G>T | p.Glu1216Ter | Pathogenic | ★☆☆☆ | Geleophysic dysplasia 3 |
c.974_975del | p.Thr325fs | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
c.9del | p.Arg5fs | Pathogenic | ★☆☆☆ | Brachyolmia-amelogenesis imperfecta syndrome |
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
Biallelic pathogenic variants in LTBP3 have been associated with conditions affecting skeletal development and dental enamel formation. These disorders reflect the gene's role in tissues where TGF-beta signalling is essential for normal growth and mineralisation. Clinical presentations may include abnormalities of bone structure, short stature, and defects in tooth enamel quality. The spectrum of features varies depending on the specific variants inherited and their effect on protein function.
No disease links recorded for this gene in our reference set.
Inheritance pattern
Conditions caused by pathogenic LTBP3 variants typically follow autosomal recessive inheritance.
When both parents are carriers, each child has a 25% chance of being affected, 50% of being a carrier, and 25% of being unaffected.
UK clinical status
Within the NHS Genomic Medicine Service, LTBP3 holds green (high-evidence) classification on multiple clinical panels. It appears on the Amelogenesis imperfecta panel (R340), reflecting its role in tooth enamel disorders, and the Skeletal dysplasia panel (R104) for bone development conditions. The gene is also listed on the Fetal anomalies panel (R21) and the Developmental Disorders Genotype-to-Phenotype (DDG2P) database, indicating relevance for prenatal and paediatric genetic diagnosis. This panel inclusion means variants in LTBP3 may be reported in NHS genomic testing when investigating skeletal or dental developmental abnormalities.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
How is LTBP3 inherited?
LTBP3-related conditions follow autosomal recessive inheritance. An individual must inherit pathogenic variants in both gene copies (one from each parent) to develop clinical features. Parents who each carry one variant are typically unaffected carriers.
What does the LTBP3 protein do?
The LTBP3 protein binds and stores inactive TGF-beta in the extracellular matrix, controlling when and where this growth factor becomes available to cells. This regulation is particularly important for normal skeletal and dental development.
Why is LTBP3 on NHS clinical panels?
LTBP3 is included on NHS panels for skeletal dysplasia, amelogenesis imperfecta, and foetal anomalies because pathogenic variants cause developmental disorders affecting bones and teeth. Green classification indicates strong evidence linking the gene to these conditions.