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PTEN
phosphatase and tensin homolog
PTEN encodes a phosphatase enzyme that regulates cell growth and division, with pathogenic variants causing Cowden syndrome and increased cancer susceptibility. The PTEN gene produces an enzyme that acts as a critical brake on cell proliferation, preventing uncontrolled growth that can lead to tumour formation.
PTEN is located on the long (q) arm of chromosome 10, at band 10q23.31. Arm ratio per GRCh38 - banding schematic.
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Overview
The PTEN gene encodes phosphatase and tensin homologue, a lipid and protein phosphatase that functions as one of the most frequently inactivated tumour suppressors across human cancers. Present in nearly all tissues, this enzyme regulates the phosphoinositide 3-kinase (PI3K) signalling pathway by removing phosphate groups from phosphatidylinositol lipids at the cell membrane, controlling cellular decisions about growth, survival and metabolism.
Pathogenic germline variants in PTEN cause a spectrum of conditions collectively termed PTEN hamartoma tumour syndrome, the most common manifestation being Cowden syndrome. Individuals with these inherited changes face markedly increased lifetime risks for several malignancies, particularly breast cancer, thyroid cancer and endometrial cancer. The gene also exhibits a high rate of somatic mutation in sporadic cancers, especially prostate and endometrial tumours, underscoring its central role in preventing oncogenesis.
Because of the significant cancer risks associated with pathogenic PTEN variants, the gene is included in the American College of Medical Genetics and Genomics Secondary Findings recommendations (ACMG SF v3.2). Clinical management for carriers typically involves enhanced surveillance protocols beginning at young ages, including annual breast screening with MRI and ultrasound, thyroid monitoring, and colonoscopy, alongside consideration of risk-reducing strategies. Genetic testing for PTEN is available through the NHS for individuals meeting criteria for PTEN hamartoma tumour syndrome evaluation.
What the gene does
The PTEN protein operates primarily as a dual-specificity phosphatase, removing phosphate groups from both lipid and protein substrates, though its lipid phosphatase activity is considered most critical for tumour suppression. At the cellular membrane, PTEN converts phosphatidylinositol (3,4,5)-trisphosphate (PIP3) back to phosphatidylinositol (4,5)-bisphosphate (PIP2), directly opposing the activity of PI3K enzymes. This dephosphorylation event serves as the rate-limiting step in attenuating PI3K-AKT-mTOR signalling, a central pathway governing cell growth, proliferation, protein synthesis and metabolism.
By reducing PIP3 levels at the membrane, PTEN prevents recruitment and activation of AKT kinase, thereby blocking downstream signals that promote cell survival and inhibit apoptosis. When PTEN function is lost through mutation, cells accumulate PIP3, leading to constitutive AKT activation, resistance to growth-inhibitory signals, and evasion of programmed cell death. This molecular mechanism explains why PTEN loss confers such potent oncogenic potential across diverse tissue types.
Beyond its canonical membrane-localised phosphatase activity, evidence suggests PTEN also functions within the nucleus, where it may contribute to maintaining chromosomal stability, regulating DNA repair processes, and controlling cell-cycle progression through phosphatase-independent mechanisms. The enzyme influences cell migration and adhesion by modulating focal adhesion assembly and cytoskeletal dynamics, affecting both developmental processes and cancer metastasis. PTEN additionally appears to suppress angiogenesis, the formation of new blood vessels that tumours require for sustained growth.
For optimal activity, PTEN functions as a homodimer, with two PTEN molecules associating before or during membrane binding. The protein's catalytic activity depends on precise positioning at the membrane interface, where the phosphatase domain engages lipid substrates whilst the C2 domain mediates membrane association through electrostatic interactions with negatively charged phospholipids. Post-translational modifications including phosphorylation, ubiquitination and oxidation regulate PTEN stability, localisation and enzymatic activity, providing multiple layers of control over this critical tumour suppressor.
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Chromosome location
PTEN resides on the long arm of chromosome 10 at cytogenetic band 10q23.31, a chromosomal region frequently deleted in human cancers. The gene spans approximately 105 kilobases of genomic DNA and comprises nine exons, with exon 1 containing 5' untranslated sequence and the protein-coding sequence beginning in exon 2. The relatively compact genomic organisation facilitates comprehensive sequencing in clinical diagnostic settings.
Chromosome 10q23 represents a tumour suppressor hotspot, with loss of heterozygosity at this locus observed across numerous cancer types. Deletions encompassing PTEN often extend to neighbouring genes, though PTEN itself appears to be the principal tumour suppressor target in this region. The chromosomal position makes PTEN susceptible to large genomic rearrangements, and whole-gene deletions account for a notable fraction of pathogenic germline variants in PTEN hamartoma tumour syndrome.
Protein structure
The 403-amino-acid PTEN protein comprises two conserved structural modules followed by an extended carboxy-terminal tail. At the amino terminus, a phosphatase tensin-type domain (residues 14-185) houses the catalytic machinery responsible for removing phosphate groups. This region adopts a classic protein tyrosine phosphatase fold featuring the signature active-site motif, with a catalytic cysteine residue performing nucleophilic attack on phosphate. Structural studies reveal the active site can accommodate the bulky inositol headgroup of PIP3, enabling the enzyme's lipid phosphatase activity.
Adjacent to the catalytic module, the C2 tensin-type domain (residues 190-350) mediates membrane association through calcium-independent interactions with phospholipid bilayers, recognising negatively charged membrane surfaces and positioning the phosphatase domain for optimal substrate engagement. Cancer-associated mutations frequently map to the interface between these two domains, disrupting either catalytic function or membrane localisation. A region required for interaction with NOP53 spans residues 338-348, linking PTEN to ribosome biogenesis and additional tumour-suppressive mechanisms beyond PI3K pathway regulation.
The carboxy-terminal tail exhibits a disordered region (residues 352-403) lacking fixed three-dimensional structure in solution yet containing critical regulatory elements including phosphorylation sites that modulate protein stability and multiple ubiquitination sites controlling PTEN turnover. At the extreme carboxy terminus, a PDZ domain-binding motif (residues 401-403) enables interactions with scaffolding proteins that influence subcellular localisation and activity. The tail region also harbours binding sites for proteins involved in PTEN membrane recruitment, and deletion or mutation of tail sequences commonly occurs in cancer, suggesting this apparently unstructured region plays essential regulatory roles.
Key variants
The PTEN variant landscape encompasses several hundred documented pathogenic and likely pathogenic germline alterations causing PTEN hamartoma tumour syndrome, alongside thousands of somatic mutations identified in sporadic cancers. Germline variants span the full spectrum of mutation types: missense changes affecting catalytic residues or membrane-binding surfaces, nonsense and frameshift variants leading to premature termination, splice-site alterations disrupting mRNA processing, and whole-gene or multi-exon deletions detectable only through copy-number analysis.
Missense variants cluster within the phosphatase and C2 domains, where single amino-acid substitutions can abolish enzymatic activity, prevent membrane localisation, or destabilise protein folding. Truncating variants (nonsense, frameshift, essential splice-site) typically result in loss of protein expression through nonsense-mediated decay or production of non-functional fragments. Because PTEN functions as a tumour suppressor, heterozygous loss-of-function variants are sufficient to confer disease risk, consistent with autosomal dominant inheritance with high penetrance for PTEN hamartoma tumour syndrome features.
Genotype-phenotype correlations suggest that variants completely abolishing PTEN function may associate with more severe manifestations, including developmental features such as macrocephaly and autism spectrum disorder, whilst variants retaining partial activity might present primarily with cancer predisposition. However, substantial phenotypic variability exists even among individuals carrying identical variants, indicating modifier genes and environmental factors influence clinical outcomes. Somatic PTEN alterations in tumours commonly involve homozygous inactivation through deletion, mutation or promoter methylation, reflecting the classical two-hit tumour suppressor model.
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.100G>C | p.Ala34Pro | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.1026+1G>A | - | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.1027-1G>A | - | Pathogenic | ★★★☆ | not provided |
c.1034T>C | p.Leu345Pro | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.103A>G | p.Met35Val | Pathogenic | ★★★☆ | not provided |
c.104T>G | p.Met35Arg | Pathogenic | ★★★☆ | Cowden syndrome 1 |
c.107G>A | p.Gly36Glu | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.113C>T | p.Pro38Leu | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.1212A>T | p.Ter404Cys | Pathogenic | ★★★☆ | Hereditary cancer-predisposing syndrome |
c.139A>G | p.Arg47Gly | Pathogenic | ★★★☆ | PTEN hamartoma tumor 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
Germline pathogenic variants in PTEN cause a clinically heterogeneous group of disorders unified under the term PTEN hamartoma tumour syndrome, with Cowden syndrome representing the most frequent and well-characterised phenotype. Cowden syndrome manifests with multiple hamartomas (benign tumour-like growths) affecting skin, oral mucosa, gastrointestinal tract and other tissues, alongside macrocephaly and characteristic dermatological findings including trichilemmomas and papillomatous papules. The defining feature, however, is markedly elevated cancer risk, particularly for breast, thyroid and endometrial malignancies.
Women with Cowden syndrome face substantially increased lifetime breast cancer risks, with thyroid cancer, predominantly follicular subtype, also occurring at elevated frequency. Endometrial cancer risk is similarly raised above population baseline. Additional malignancies including colorectal, renal cell and melanoma occur at increased frequency. Clinical diagnostic criteria for Cowden syndrome incorporate these cancer histories alongside pathognomonic mucocutaneous lesions, macrocephaly, and the presence of specific benign features.
Bannayan-Riley-Ruvalcaba syndrome, another manifestation of germline PTEN variants, presents in childhood with macrocephaly, lipomas, haemangiomas and pigmented macules of the glans penis in males. Some individuals initially diagnosed with Bannayan-Riley-Ruvalcaba syndrome later develop cancer risks typical of Cowden syndrome, reinforcing that these represent a phenotypic spectrum rather than distinct entities. PTEN variants have also been identified in subsets of individuals with autism spectrum disorder and developmental delay, particularly when accompanied by macrocephaly, though not all individuals with germline PTEN pathogenic variants develop neurodevelopmental features. The clinical variability necessitates individualised surveillance and management approaches informed by personal and family history alongside genetic findings.
Inheritance pattern
Conditions caused by pathogenic PTEN variants typically follow autosomal dominant inheritance.
Each child has a 50% chance of inheriting the pathogenic variant, regardless of sex.
UK clinical status
PTEN holds green (high-confidence) status across numerous NHS England Genomic Medicine Service gene panels, reflecting its well-established clinical validity and actionability. The gene appears on the PTEN Hamartoma Tumour Syndrome panel (R213), which provides the diagnostic pathway for individuals presenting with suggestive features. PTEN is also included in multiple cancer predisposition panels covering familial breast cancer, inherited polyposis and early onset colorectal cancer (R211), endometrial cancer, thyroid cancer, renal cancer and childhood solid tumours, acknowledging the broad cancer spectrum associated with pathogenic variants.
The inclusion in the adult and childhood solid tumour cancer susceptibility panels enables PTEN testing when family history or tumour characteristics raise suspicion for hereditary cancer predisposition. Presence on the segmental overgrowth disorders panel (R110) and related panels addressing developmental anomalies reflects recognition of PTEN's role in growth dysregulation syndromes such as Bannayan-Riley-Ruvalcaba syndrome. Green designation on the intellectual disability panel (R29) and early onset or syndromic epilepsy panel (R59) acknowledges the association between PTEN pathogenic variants and neurodevelopmental presentations.
Green status indicates that NHS clinical geneticists and oncologists can request PTEN sequencing and deletion/duplication analysis for eligible patients through routine genomic testing pathways. Eligibility criteria typically require meeting clinical diagnostic criteria for PTEN hamartoma tumour syndrome, having suggestive personal or family cancer history, or presenting with relevant developmental features such as macrocephaly with neurodevelopmental concerns. Testing may be pursued as a single-gene test when clinical suspicion is high or as part of multi-gene panel testing for hereditary cancer or developmental disorders. Results inform personalised surveillance strategies and reproductive options, with genetic counselling forming an integral component of the testing pathway.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Diet & lifestyle considerations
Research examining lifestyle factors in individuals with germline PTEN pathogenic variants remains limited, though general cancer prevention principles apply alongside syndrome-specific surveillance. Maintaining a healthy body weight may be particularly relevant, as the PI3K-AKT-mTOR pathway that PTEN regulates integrates nutrient and growth-factor signals, and obesity can promote pathway activation. Some studies in the general population suggest that excess adiposity increases risk for several of the cancers elevated in Cowden syndrome, including breast, endometrial and colorectal malignancies, though whether this relationship holds the same magnitude in PTEN variant carriers remains uncertain.
Dietary patterns emphasising plant-based whole foods, limited processed meats and moderation of alcohol consumption align with general cancer-prevention guidance and may offer benefit, though no specific dietary intervention has been proven to reduce cancer incidence in PTEN hamartoma tumour syndrome. Regular physical activity supports overall health and has demonstrated associations with reduced breast and colorectal cancer risk in population studies, though evidence specific to individuals with germline PTEN variants is lacking. Any dietary or lifestyle modifications should be discussed with healthcare providers and considered complementary to, not substitutes for, recommended surveillance protocols.
Smoking avoidance is essential, as tobacco use compounds cancer risk and may have particular relevance given the thyroid cancer predisposition in Cowden syndrome. Sun protection through sunscreen, protective clothing and avoidance of intense midday sun exposure is advisable given the increased melanoma risk. Psychosocial support may benefit individuals navigating the anxiety and decision-making challenges associated with high cancer risk, and many find value in connecting with others managing similar genetic conditions through support organisations.
Supplement considerations
No dietary supplement has been demonstrated in rigorous clinical trials to prevent cancer or reduce tumour risk specifically in individuals carrying germline PTEN pathogenic variants. Whilst the PI3K-AKT-mTOR pathway represents a therapeutic target, and compounds such as rapamycin (sirolimus) that inhibit mTOR are under investigation in research settings, these are prescription medications requiring medical supervision and are not appropriate for self-administration as preventive supplements.
Some individuals inquire about antioxidant supplements, given PTEN's role in cellular stress responses, but evidence does not support vitamin E, selenium or other antioxidant supplementation for cancer prevention in high-risk populations, and some trials have suggested potential harm from high-dose supplementation. Vitamin D has attracted interest due to its roles in cell differentiation and potential anti-cancer properties, though whether supplementation influences cancer risk in PTEN variant carriers is unknown. Routine vitamin D supplementation to maintain adequate levels for bone health is reasonable when guided by blood testing and clinician recommendation, but should not be undertaken with the expectation of cancer risk reduction.
Green tea extracts, curcumin and numerous other compounds have shown laboratory effects on PI3K pathway signalling in cell culture or animal models, but translating these findings to meaningful clinical benefit in humans remains speculative. Individuals considering any supplement should discuss with their GP or genetic counsellor, as some supplements may interact with medications or surveillance procedures. The cornerstone of cancer risk management in PTEN hamartoma tumour syndrome remains evidence-based surveillance and, when appropriate, risk-reducing surgery rather than supplementation.
Frequently asked questions
What cancers are associated with pathogenic PTEN variants?
Individuals with germline PTEN pathogenic variants face substantially elevated lifetime risks for breast cancer, thyroid cancer (predominantly follicular subtype), endometrial cancer, and increased risks for colorectal cancer, renal cell carcinoma and melanoma. Cancer surveillance protocols typically begin in young adulthood or earlier depending on family history.
How is Cowden syndrome diagnosed?
Diagnosis combines clinical criteria (including characteristic skin lesions, macrocephaly, hamartomas and personal or family cancer history) with genetic testing confirming a pathogenic PTEN variant. Some individuals meet clinical diagnostic criteria without an identified PTEN variant, whilst others carry PTEN variants with milder or atypical presentations, requiring individualised clinical interpretation.
What surveillance is recommended for PTEN variant carriers?
Guidelines typically recommend annual breast MRI and mammography beginning by age 30-35 (or earlier based on family history), annual thyroid ultrasound from diagnosis, baseline colonoscopy by age 35 with repeat every five years, and consideration of endometrial surveillance in women. Dermatological examination and ongoing clinical evaluation for additional features are also advised, with protocols tailored to individual and family history.
Can children inherit PTEN pathogenic variants?
Yes, PTEN-related conditions follow autosomal dominant inheritance, meaning each child of an affected parent has a 50 per cent chance of inheriting the variant. Genetic counselling can discuss reproductive options including preimplantation genetic testing, prenatal diagnosis, and the implications of at-risk status for children, who may benefit from early surveillance if found to carry a familial PTEN variant.
What is the difference between germline and somatic PTEN variants?
Germline variants are inherited or arise during early development, present in all body cells, and confer predisposition to PTEN hamartoma tumour syndrome with elevated cancer risks. Somatic variants occur only in tumour cells during a person's lifetime, contribute to cancer development in that specific tumour, but are not inherited and do not indicate a hereditary syndrome requiring family screening.
Are there treatments specifically for PTEN-related conditions?
Current management focuses on enhanced surveillance for early cancer detection and consideration of risk-reducing surgeries such as prophylactic mastectomy or hysterectomy after individualised discussion of benefits and risks. Research is exploring mTOR inhibitors and other targeted therapies, but these remain investigational for cancer prevention in PTEN variant carriers and are not part of standard care outside clinical trials.
References
- Yehia L, Keel E, Eng C. The Clinical Spectrum of PTEN Mutations. Annual review of medicine. 2020. PMID: 31433956
- Yehia L, Eng C. PTEN hamartoma tumour syndrome: what happens when there is no PTEN germline mutation? Human molecular genetics. 2020. PMID: 32568377
- Yehia L, Ngeow J, Eng C. PTEN-opathies: from biological insights to evidence-based precision medicine. The Journal of clinical investigation. 2019. PMID: 30614812
- Yehia L, Eng C. 65 YEARS OF THE DOUBLE HELIX: One gene, many endocrine and metabolic syndromes: PTEN-opathies and precision medicine. Endocrine-related cancer. 2018. PMID: 29792313
- Tilot AK, Frazier TW 2nd, Eng C. Balancing Proliferation and Connectivity in PTEN-associated Autism Spectrum Disorder. Neurotherapeutics : the journal of the American Society for Experimental NeuroTherapeutics. 2015. PMID: 25916396
- Kechagioglou P, Papi RM, Provatopoulou X. Tumor suppressor PTEN in breast cancer: heterozygosity, mutations and protein expression. Anticancer research. 2014. PMID: 24596386
- Bubien V, Bonnet F, Brouste V. High cumulative risks of cancer in patients with PTEN hamartoma tumour syndrome. Journal of medical genetics. 2013. PMID: 23335809
- Pilarski R, Burt R, Kohlman W. Cowden syndrome and the PTEN hamartoma tumor syndrome: systematic review and revised diagnostic criteria. Journal of the National Cancer Institute. 2013. PMID: 24136893
- Tan MH, Mester JL, Ngeow J. Lifetime cancer risks in individuals with germline PTEN mutations. Clinical cancer research : an official journal of the American Association for Cancer Research. 2012. PMID: 22252256
- Song MS, Salmena L, Pandolfi PP. The functions and regulation of the PTEN tumour suppressor. Nature reviews. Molecular cell biology. 2012. PMID: 22473468
- He X, Ni Y, Wang Y. Naturally occurring germline and tumor-associated mutations within the ATP-binding motifs of PTEN lead to oxidative damage of DNA associated with decreased nuclear p53. Human molecular genetics. 2011. PMID: 20926450
- Butler MG, Dasouki MJ, Zhou XP. Subset of individuals with autism spectrum disorders and extreme macrocephaly associated with germline PTEN tumour suppressor gene mutations. Journal of medical genetics. 2005. PMID: 15805158
- Adam MP, Bick S, Mirzaa GM. PTEN Hamartoma Tumor Syndrome. 1993. PMID: 20301661