PMS2 Gene and Lynch Syndrome: Cancer Risk and Testing Limits

01 / 10

What is the PMS2 gene?

The PMS2 gene, on chromosome 7 at 7p22.1, makes a protein that pairs with MLH1 to form MutL alpha, which helps repair copying mistakes in DNA. A harmful change in one copy causes Lynch syndrome. PMS2 variants account for 5–25% of Lynch syndrome. ^[1,13]

PMS2 is a mismatch-repair endonuclease. NCBI lists the aliases MLH4, PMSL2, HNPCC4, LYNCH4 and MMRCS4. About 1 in 750 people in the United States carries a PMS2 variant, according to FORCE citing NIH All of Us data; PMS2 is therefore the most prevalent of the four mismatch-repair gene variants even though its penetrance is lowest. Lynch syndrome overall affects about 1 in 280–600 people. MedlinePlus says PMS2 variants account for fewer than 25% of Lynch diagnoses. ^[1,3,9,13]

Read the Lynch syndrome overview for the condition-level picture.

02 / 10

How do PMS2 variants cause Lynch syndrome?

PMS2 variants cause Lynch syndrome by switching off one working copy of a DNA-repair gene. A cell can repair DNA until a later “second hit” disables the remaining copy. PMS2 carries lower cancer risk and later average onset than the other Lynch genes. ^[1]

This loss-of-function mechanism allows DNA-copying errors to accumulate. Because MLH1 and PMS2 work as a pair, loss patterns in tumours are interpreted together. ClinGen classified the PMS2–Lynch syndrome relationship as Definitive on December 30, 2022 and rates adult clinical actionability Strong; evidence for paediatric Lynch actionability is insufficient. Variant interpretation follows ACMG/AMP principles and the PMS2 Variant Curation Expert Panel specification. ^[1,7,12]

03 / 10

PMS2 cancer risk by cancer type, age and sex

People with a pathogenic PMS2 variant have the lowest cancer risks of the four Lynch genes, led by endometrial and colorectal cancer. NCCN Version 1.2026 gives 8.7–20% lifetime risk for colorectal cancer and 13–26% for endometrial cancer. GeneReviews reports 13% endometrial risk by age 65. ^[1,2,3]

Cumulative risk through age 65

General population and PMS2 carrier cumulative cancer risk through age 65, female and male.
Cancer	General population F / M	PMS2 carriers F / M
Colon	0.45% / 0.6%	3% / 9.5%
Rectum	0.3% / 0.5%	2% / 0%
Endometrium	0.6%	13%
Ovary	0.5%	2.5%
Ureter, kidney	0.2% / 0.35%	0% / 0%
Prostate	1% (M)	3% (M)
Small bowel	Unknown	2% / 3%
Bladder	0.1% / 0.35%	0% / 0%
Gastric	0.3% / 0.6%	0% / 3%
Brain	0.2% / 0.25%	7% / 0%
Bile duct	Unknown	0% / 0%
Pancreas	0.2% / 0.25%	0% / 0%

Source: GeneReviews Table 3, updated September 17, 2026; PLSD included 8,500 carriers and 71,713 follow-up years, but only 549 PMS2 carriers. Rare-cancer cells—including the 7% brain figure in women—rest on very few cases and are not firm risk estimates. GeneReviews reports no confidence intervals in this table. ^[1]

NCCN lifetime ranges

Cancer	PMS2 lifetime risk	General population	Average diagnosis age: PMS2 / general
Colorectal	8.7–20%	4%	61–66 / 68–72
Endometrial	13–26%	3.1%	49–50 / 60

NCCN Version 1.2026 as reproduced by FORCE on September 24, 2026. FORCE lists only these two PMS2-specific lifetime ranges. ^[2,3]

Published figures answer different questions. Myriad reports colorectal risk up to 20% and endometrial risk 12–26%. eviQ reports bowel risk near 20% in men and 15% in women, endometrial risk around 15% and ovarian risk around 3%. MedlinePlus reports about 22% for all cancers combined by age 70, not for either one cancer. ^[9,14,15]

PLSD median onset was 71.3 years for colorectal cancer in men, 66.1 in women and 61.2 for endometrial cancer, with wide intervals. GeneReviews gives mean colorectal onset of 66–71 in PLSD, close to about 70 in the general population; a 284-family study found 60–63 for colorectal and 55–56 for endometrial cancer. Early-onset colorectal cancer remains possible. Gynaecological cancers were more frequent than colorectal cancer in PMS2 carriers in the 2023 analysis, reaching 23.3% cumulative incidence by 75. ^[1,4,10,11]

A relatively common variant can still have low penetrance: many carriers never develop cancer. For sex-specific context, see endometrial and ovarian cancer in Lynch syndrome.

04 / 10

How PMS2 differs from the other Lynch genes

PMS2 carries the lowest cancer risk of the four Lynch genes, with later-onset colorectal cancer and mean diagnosis age close to the general population. By age 65, PLSD estimates colon cancer risk at 3% in women and 9.5% in men with PMS2. ^[1]

Cancer risk through age 65 by Lynch syndrome gene.
Cancer through 65	PMS2	MSH6	MSH2	MLH1
Colon F / M	3% / 9.5%	10% / 13%	30% / 41.5%	36% / 48%
Endometrium	13%	32%	38%	32%
Ovary	2.5%	3%	11%	8%

These GeneReviews/PLSD values include only 549 PMS2 carriers, so small differences—especially for rare cancers—should not be overinterpreted. ^[1]

NCCN-based FORCE guidance starts discussion of risk-reducing hysterectomy at age 50 for PMS2, later than age 40 for MLH1, MSH2 and MSH6. Compare the MLH1 gene, MSH2 gene and MSH6 gene. ^[2,3]

05 / 10

What does “PMS2 positive” mean?

On a genetic test report, “PMS2 positive” means a pathogenic or likely pathogenic variant was found in PMS2, which establishes Lynch syndrome. On a tumour pathology report, “PMS2 positive” usually means the PMS2 protein is present on staining—the normal result. A variant of uncertain significance neither confirms nor rules out Lynch syndrome. ^[1,12]

Report context	What “positive” usually means	What happens next
Germline genetic test	A pathogenic or likely pathogenic PMS2 variant was identified	Genetic counselling, confirmation when appropriate, gene-specific surveillance and family testing
Tumour IHC	PMS2 protein is retained on staining	Interpret PMS2 together with MLH1 and the other mismatch-repair proteins
Variant of uncertain significance	Evidence cannot show whether the variant is harmful	Do not use it alone to diagnose Lynch syndrome or make irreversible decisions

Pathogenic and likely pathogenic variants are treated alike under ACMG/AMP classification. A positive genetic result is not a diagnosis of cancer. Read about tumour MSI and IHC testing. ^[1,12]

06 / 10

How PMS2 variants run in families

A PMS2 variant is inherited in an autosomal dominant pattern: each child of a carrier has a 50% chance of inheriting it, and the variant does not skip generations. Relatives can be tested for the one known family variant. A child who inherits pathogenic PMS2 variants from both parents has a separate, more severe condition. ^[1,3]

50%

Each pregnancy is an independent event. Because PMS2 is relatively common and has low penetrance, a carrier may have no striking family history. Cascade testing begins with the exact familial variant rather than an unrestricted search.

Biallelic PMS2 variants can cause constitutional mismatch repair deficiency (CMMRD). Most first tumours occur before age 18, and about half of affected children develop cancer by age 10. ClinGen classifies the PMS2–CMMRD relationship as Definitive. Suspected CMMRD needs specialist paediatric genetics care. ^[1,7]

07 / 10

Screening and prevention for PMS2 carriers

For people with a PMS2 variant, NCCN Version 1.2026 advises colonoscopy every 1–3 years starting at age 30–35, or 2–5 years before the youngest colorectal cancer in the family if it occurred before 30. Risk-reducing hysterectomy is discussed from age 50. Plans are individual and set with a genetic counsellor or clinician. ^[1,2,3]

Area	When to discuss or start	Interval / note
Colonoscopy	Age 30–35; or 2–5 years before a family diagnosis before 30	Every 1–3 years; FORCE notes yearly may be considered for men, people over 40 and those with polyps or colorectal cancer
Endometrial biopsy	Discuss from age 30–35	Consider every 1–2 years; evidence that screening lowers mortality is limited
Transvaginal ultrasound	After menopause	May be considered; it is not a reliable stand-alone screen
Hysterectomy with salpingectomy	Discuss from age 50	Individual decision after childbearing and review of benefits and harms
Aspirin	Discuss with a clinician	Dose and timing are individualized
Other cancers	General population screening	Additional surveillance only when family history or another risk factor supports it

Guidance is not identical. eviQ—reviewed April 16, 2024 and overdue for review after December 31, 2025—uses colonoscopy every 1–2 years from 35 and says there is no reliable endometrial screening method. Myriad starts colonoscopy at 30–35 and discusses hysterectomy at 50 or after menopause. ^[14,15]

For the fuller pathway, see the colonoscopy schedule and aspirin and endometrial and ovarian cancer in Lynch syndrome.

08 / 10

How PMS2 variants are found, and why PMS2 is hard to test

PMS2 is harder to test than the other Lynch genes because the genome holds near-identical copies of part of it. The pseudogene PMS2CL closely matches PMS2 exons 11–15, so short reads can find a variant without showing whether it sits in PMS2 or the pseudogene. Specialised methods may be needed. ^[1,5]

Sequence analysis

45–80%

Share of PMS2 pathogenic variants found by sequence analysis in GeneReviews Table 1.

Deletion / duplication

20–55%

Large rearrangements may represent 20–50% of PMS2 findings.

Reflex workflow

92% / 8%

Resolved by short-read sequencing / required long-range PCR.

GeneReviews advises using a laboratory with PMS2 expertise. Long-range PCR, cDNA analysis or specialised sequencing can assign an ambiguous finding to the gene or pseudogene. Han and colleagues described an approximately 11 kb high-homology region spanning exons 12–15 in whole-genome data. The often-repeated “98% identity” figure is not used here because the brief did not supply a verified primary source. ^[1,6]

In Gould and colleagues’ reflex workflow, more than 99% analytical sensitivity and specificity for single-nucleotide variants and small insertions/deletions was achieved; 92% of samples resolved with short-read sequencing and 8% needed long-range PCR. These are results for that validated workflow, not every test. ^[5]

Tumour MSI and IHC use tumour tissue and do not replace germline analysis. A medically consequential germline finding calls for confirmation and counselling. Read how Lynch syndrome genetic testing works and tumour MSI and IHC testing.

09 / 10

PMS2 questions people ask

Q1What does PMS2 positive mean?

On a germline test, it means a pathogenic or likely pathogenic PMS2 variant was found and establishes Lynch syndrome. On tumour IHC, “positive” generally means PMS2 protein is present. A positive genetic result is not a cancer diagnosis. ^[1,12]

Q2What are the cancer risks associated with a PMS2 mutation?

NCCN Version 1.2026 gives lifetime ranges of 8.7–20% for colorectal cancer and 13–26% for endometrial cancer. GeneReviews reports sex-specific risks through age 65; estimates differ by endpoint, cohort and age. ^[1,2,3]

Q3Can you live a normal life with Lynch syndrome?

Many PMS2 carriers never develop cancer, and PMS2 has the lowest risk of the four mismatch-repair genes. No single life-expectancy figure applies. Recommended surveillance is intended to prevent colorectal cancer or find cancer earlier. ^[1] Lynch syndrome life expectancy

Q4What is the link between PMS2 and breast cancer?

ClinGen rated the claimed PMS2–hereditary breast cancer relationship “Disputed” on December 21, 2023. Follow general breast screening unless personal or family history supports a different plan. ^[8]

Q5Is PMS2 hard to test?

Yes. PMS2CL closely resembles part of PMS2, so short reads may not show which location contains a variant. GeneReviews recommends a laboratory with PMS2 expertise and specialised methods when needed. ^[1,5]

Q6Does everyone with a PMS2 variant get cancer?

No. PMS2 has incomplete penetrance, meaning cancer risk is above population risk but remains below 100%. Risk changes with age, sex and family history. ^[1]

10 / 10

Why whole-genome sequencing, and where it falls short

Whole-genome sequencing reads broadly across the genome, whereas a Lynch panel reads a fixed list of genes with methods chosen for a clinical question. HLI’s $599 service reports a cancer risk assessment covering BRCA1 and BRCA2 among other genes, but its PMS2 coverage and pseudogene workflow are unconfirmed. A genome finding is a starting point, not a diagnosis.

Route	What it can add	Important limit
Clinical Lynch / multigene panel	Clinician-ordered after counselling; expert laboratories use long-range PCR or specialised NGS for PMS2 and include deletion/duplication analysis	A fixed gene list; nevertheless the stronger first option for a known family variant or strong personal/family history
Tumour-first pathway	IHC and MSI can identify mismatch-repair loss in colorectal or endometrial tumour tissue	Not a germline diagnosis; PMS2 loss is interpreted with MLH1 and can lead to germline testing
23andMe	The clinician-ordered Total Health exome report lists MLH1, MSH2, MSH6 and PMS2	The standard Health Predisposition reports do not include Lynch genes; this is an exome, not a genome, and no price was shown on the source page ^[17]
HLI whole-genome sequencing · $599	Broad sequence at approximately 30× average coverage and risk reporting beyond one syndrome	Coverage is not guaranteed at every position. PMS2 exons 11–15, copy-number performance, report coverage and confirmation workflow are unpublished

The PMS2-specific limit

Do not assume a broad genome report resolves the PMS2 pseudogene region.

HLI has not published how its pipeline handles PMS2 exons 11–15, deletion and duplication calls, or confirmation. Ask any laboratory how it analyses this region. WGS does not test tumour MSI/IHC, find an existing cancer, replace screening or guarantee that every PMS2 variant will be detected.

A clinic-ordered panel may be insurance-covered when criteria are met and is purpose-built for this question. Whole-genome sequencing can add breadth, but a relevant finding needs confirmatory clinical testing and review with a genetic counsellor; counselling is not promised as part of the HLI service. Compare BRCA1 and BRCA2 risk.

See what the $599 genome service includes

References and review notes

Sources and versions were reviewed October 5, 2026. GeneReviews, NCCN and ILSD should be checked every six months and whenever revised; next planned review is January 5, 2027. Publication remains blocked on a named author, medical reviewer and molecular-genetics review of the PMS2 testing section. HLI assay coverage remains unverified.