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BMPR1A
bone morphogenetic protein receptor type 1A
The BMPR1A gene provides instructions for a protein critical in cell growth, division, and differentiation, primarily through the transforming growth factor beta (TGF-β) signalling pathway. BMPR1A, or bone morphogenetic protein receptor type 1A, encodes a receptor protein that plays a pivotal role in cellular communication.
BMPR1A is located on the long (q) arm of chromosome 10, at band 10q23.2. Arm ratio per GRCh38 - banding schematic.
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Overview
The BMPR1A gene, full name bone morphogenetic protein receptor type 1A, is fundamental for proper cellular function throughout the body. It encodes a protein that acts as a receptor on the cell surface, meaning it receives external signals and transmits them inside the cell. This protein is a key component of the transforming growth factor beta (TGF-β) signalling pathway, which orchestrates cell growth, proliferation, differentiation, and programmed cell death.
Pathogenic variations within the BMPR1A gene can disrupt this crucial signalling, leading to uncontrolled cell growth and an increased susceptibility to certain diseases. BMPR1A function is central to comprehending the mechanisms underlying conditions such as inherited cancer syndromes, where its proper function is compromised.
What the gene does
The BMPR1A gene directs the synthesis of the bone morphogenetic protein receptor 1A protein, a transmembrane receptor. This protein sits at the cell surface, where it interacts with molecules from the surrounding environment. Its primary role involves recognising and attaching to specific signalling molecules, known as ligands, that belong to the transforming growth factor beta (TGF-β) superfamily of proteins. The receptor contains a specialised site designed to accommodate these ligands.
Once a ligand docks with the BMPR1A receptor, the receptor undergoes a change that switches on an intracellular signalling cascade. This activation process typically involves adding phosphate groups to a family of proteins known as SMAD proteins. After phosphorylation, these SMAD proteins assemble into a complex that travels into the cell's nucleus. Within the nucleus, the SMAD complex functions as a transcription factor, directly influencing which genes are expressed. These target genes control diverse cellular activities, including growth, division (proliferation), differentiation, and apoptosis (programmed cell death). Through its regulation of these fundamental cellular activities, the BMPR1A protein helps maintain proper tissue development, maintenance, and repair.
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Chromosome location
The BMPR1A gene is situated on the long arm of chromosome 10, specifically at position 10q23.2. This genomic location indicates its precise address within the human genome. The gene spans a significant region of DNA and contains multiple exons, which are the coding segments of the gene that are ultimately translated into the protein. Its location on chromosome 10 suggests its potential involvement in genetic rearrangements or deletions that may affect its expression or function, contributing to various disease states.
Protein structure
The bone morphogenetic protein receptor type 1A protein consists of 532 amino acids and exhibits a modular structure essential for its receptor function. An important region for specifying ligand binding is located between amino acids 107-109, which mediates the protein's specificity for particular BMP ligands. Further into the intracellular domain, a crucial regulatory region known as the GS domain spans amino acids 204-233. This GS (Glycine-Serine rich) domain is a characteristic feature of type I TGF-β receptors and is critical for transmitting the signal by interacting with and phosphorylating downstream SMAD proteins. The Protein kinase domain extends from amino acids 234-525. This domain possesses serine/threonine kinase activity, meaning it can add phosphate groups to serine and threonine residues on other proteins, thereby initiating the intracellular signalling cascade.
Key variants
Variations within the BMPR1A gene can significantly impact the function of the encoded protein. These genetic changes can range from single nucleotide substitutions to larger deletions or insertions, and their effect depends on the specific alteration and its location within the gene. Pathogenic variants can lead to an abnormally shortened or non-functional protein, impairing its ability to bind ligands or activate the downstream signalling pathway. Such disruptions in protein function are often associated with an increased risk of developing inherited conditions, particularly those involving uncontrolled cell proliferation.
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.676delG | - | Pathogenic/Likely pathogenic | ★★☆☆ | not provided |
c.1010C>A | p.Ser337Ter | Pathogenic | ★★☆☆ | Hereditary cancer-predisposing syndrome |
c.1057C>T | p.Gln353Ter | Pathogenic | ★★☆☆ | Juvenile polyposis syndrome |
c.1061del | p.Gly354fs | Pathogenic | ★★☆☆ | Hereditary cancer-predisposing syndrome |
c.1064del | p.Lys355fs | Pathogenic | ★★☆☆ | Juvenile polyposis syndrome |
c.1081C>T | p.Arg361Ter | Pathogenic | ★★☆☆ | Hereditary cancer-predisposing syndrome |
c.111dup | p.Asp38fs | Pathogenic | ★★☆☆ | Hereditary cancer-predisposing syndrome |
c.1127dup | p.Cys376fs | Pathogenic | ★★☆☆ | Juvenile polyposis syndrome |
c.1221C>G | p.Tyr407Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Hereditary cancer-predisposing syndrome |
c.1255A>T | p.Lys419Ter | Pathogenic | ★★☆☆ | Juvenile polyposis 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
Pathogenic variants in the BMPR1A gene are notably associated with Juvenile Polyposis Syndrome. This condition is inherited in an autosomal dominant manner, meaning a single altered copy of the gene is sufficient to cause the disorder. More than 60 pathogenic variants in the BMPR1A gene have been identified that cause juvenile polyposis syndrome. Research indicates that many of these genetic changes produce a truncated, non-functional version of the receptor, preventing it from properly interacting with ligands in the TGF-β pathway. The syndrome is characterised by the development of multiple polyps in the gastrointestinal tract, particularly in the colon and rectum, during childhood or adolescence. These polyps, though often benign initially, carry an increased risk of malignant transformation, highlighting the importance of early detection and management.
Inheritance pattern
Conditions caused by pathogenic BMPR1A variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
In the UK, the BMPR1A gene is recognised within several NHS Genomic Medicine Service (GMS) pathways due to its clinical significance. It is included in panels for Adult solid tumours cancer susceptibility, Adult solid tumours for rare disease, Childhood solid tumours, and Childhood solid tumours cancer susceptibility. Additionally, BMPR1A is part of the Colorectal cancer pertinent cancer susceptibility panel and the GI tract tumours panel. It is also covered under the Inherited polyposis and early onset colorectal cancer - germline testing panel (R211), reflecting its known association with conditions like Juvenile Polyposis Syndrome and its role in cancer predisposition.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
For individuals with a pathogenic variant in BMPR1A, particularly those associated with Juvenile Polyposis Syndrome, certain lifestyle considerations may be beneficial, though these do not prevent the genetic predisposition. Clinical guidelines typically suggest regular medical surveillance, including colonoscopies, to monitor for and remove any developing polyps, which is crucial for early detection and prevention of colorectal cancer. General health recommendations for the population include maintaining a healthy body weight and engaging in regular physical activity. However, these lifestyle choices do not substitute for specific medical advice and regular screenings tailored to an individual's genetic risk.
Supplement considerations
There is no conclusive scientific evidence to suggest that specific dietary supplements can prevent the development of conditions associated with pathogenic BMPR1A variants, such as Juvenile Polyposis Syndrome, or mitigate the effects of these genetic changes. While various supplements are sometimes considered for their broader roles in health, their direct impact on BMPR1A-related conditions has not been established. Individuals considering any supplements should consult with a healthcare professional to discuss potential benefits, risks, and interactions with other medications or health conditions. Healthcare professionals generally advise against self-prescribing supplements without consultation, especially for individuals with genetic predispositions to health conditions.
Frequently asked questions
What does the BMPR1A gene do?
The BMPR1A gene provides instructions for making a receptor protein involved in the transforming growth factor beta (TGF-β) signalling pathway. This pathway is crucial for regulating cell growth, division, and differentiation throughout the body.
What happens if the BMPR1A gene doesn't work correctly?
If the BMPR1A gene doesn't function correctly, it can disrupt normal cell signalling, potentially leading to uncontrolled cell growth. This disruption is associated with an increased risk of certain conditions, including inherited cancer syndromes.
What health conditions are associated with BMPR1A variants?
Pathogenic variants in the BMPR1A gene are primarily associated with Juvenile Polyposis Syndrome, an inherited condition characterised by the development of multiple polyps in the gastrointestinal tract, which carry a risk of becoming cancerous.
How is Juvenile Polyposis Syndrome inherited?
Juvenile Polyposis Syndrome is inherited in an autosomal dominant manner. This means that an individual needs to inherit only one copy of an altered BMPR1A gene from either parent to be at risk of developing the condition.
Can diet and lifestyle changes affect BMPR1A-related conditions?
While diet and lifestyle changes cannot alter the genetic predisposition from a BMPR1A variant, maintaining a healthy lifestyle, including a balanced diet and regular screenings, is generally recommended for overall health and may help manage associated risks. Always consult a healthcare professional for personalised advice.
Is the BMPR1A gene screened in the UK?
Yes, the BMPR1A gene is included in several NHS Genomic Medicine Service panels in the UK, particularly those related to adult and childhood solid tumour cancer susceptibility and inherited polyposis syndromes.
References
- Calva-Cerqueira D, Chinnathambi S, Pechman B. The rate of germline mutations and large deletions of SMAD4 and BMPR1A in juvenile polyposis. Clinical genetics. 2009. PMID: 18823382
- Aretz S, Stienen D, Uhlhaas S. High proportion of large genomic deletions and a genotype phenotype update in 80 unrelated families with juvenile polyposis syndrome. Journal of medical genetics. 2007. PMID: 17873119
- Pyatt RE, Pilarski R, Prior TW. Mutation screening in juvenile polyposis syndrome. The Journal of molecular diagnostics : JMD. 2006. PMID: 16436638
- Howe JR, Sayed MG, Ahmed AF. The prevalence of MADH4 and BMPR1A mutations in juvenile polyposis and absence of BMPR2, BMPR1B, and ACVR1 mutations. Journal of medical genetics. 2004. PMID: 15235019
- Howe JR, Bair JL, Sayed MG. Germline mutations of the gene encoding bone morphogenetic protein receptor 1A in juvenile polyposis. Nature genetics. 2001. PMID: 11381269