KRT20

Chr 17

keratin 20

Also known as: CD20, CK-20, CK20, K20, KRT21

NCBI Gene: 54474ENSG00000171431UniProt: P35900

The protein encoded by this gene is a member of the keratin family. The keratins are intermediate filament proteins responsible for the structural integrity of epithelial cells and are subdivided into cytokeratins and hair keratins. The type I cytokeratins consist of acidic proteins which are arranged in pairs of heterotypic keratin chains. This cytokeratin is a major cellular protein of mature enterocytes and goblet cells and is specifically expressed in the gastric and intestinal mucosa. The type I cytokeratin genes are clustered in a region of chromosome 17q12-q21. [provided by RefSeq, Jul 2008]

0
Active trials
7
Pathogenic / LP
81
ClinVar variants
3
Pubs (1 yr)
0.4
Missense Z
1.30
LOEUF
Clinical Summary— KRT20
⚡
Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
📋
ClinVar Variants
7 Pathogenic / Likely Pathogenic· 66 VUS of 81 total submissions

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
Tolerant — LoF & missense variants common in population
LoF Constraint?LOEUF (Loss-of-function Observed/Expected Upper bound Fraction) is the upper bound of the 90% CI for LoF OE — the preferred gnomAD v4 metric. Lower = more intolerant to LoF. LOEUF < 0.35 = highly constrained.
1.30LOEUF
pLI 0.000
Z-score 0.56
OE 0.86 (0.59–1.30)
Tolerant

Highly tolerant — LoF variants common in population

Missense Constraint?Missense Z-score: standard deviations fewer missense variants observed vs. expected. Z > 3.09 (p < 0.001) = gene does not tolerate missense variation. OE missense < 0.6 is also considered constrained.
0.37Z-score
OE missense 0.93 (0.84–1.04)
227 obs / 243.2 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?Shaded band = 90% confidence interval. Vertical tick = point estimate. Grey threshold line = gnomAD constraint cutoff for that variant class.
LoF OE?Ratio of observed to expected LoF variants. Upper CI bound (LOEUF) ≤ 0.35 = strong LoF constraint signal.0.86 (0.59–1.30)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.93 (0.84–1.04)
0≤0.61.4
Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.1.07
0≤1.21.6
LoF obs/exp: 17 / 19.7Missense obs/exp: 227 / 243.2Syn Z: -0.56

ClinVar Variant Classifications

81 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic7
VUS66
Likely Benign5
Benign3
7
Pathogenic
66
VUS
5
Likely Benign
3
Benign

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
0
7
0
7
Likely Pathogenic
0
0
0
0
0
VUS
0
66
0
0
66
Likely Benign
0
3
0
2
5
Benign
0
1
0
2
3
Total0707481

LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly

View in ClinVar →

Protein Context — Lollipop Plot

KRT20 · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

OMIM — Genotype-Phenotype Relationships

1 OMIM entry

OMIM

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov

No active trials found for this gene.

Search ClinicalTrials.gov →
Clinical Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
Comprehensive clinicopathologic, molecular, and immunologic characterization of colorectal carcinomas with loss of three intestinal markers, CDX2, SATB2, and KRT20.
Lee JA et al.·Virchows Arch
2022
In stage pT1 non-muscle-invasive bladder cancer (NMIBC), high KRT20 and low KRT5 mRNA expression identify the luminal subtype and predict recurrence and survival.
Breyer J et al.·Virchows Arch
2017
Clinical relevance of Nectin-4 downregulation and biological changes caused by cytotoxic chemotherapy in bladder cancer.
Miyake M et al.·Cancer Chemother Pharmacol
2025
External validation of FXYD3 and KRT20 as predictive biomarkers for the presence of micrometastasis in muscle invasive bladder cancer lymph nodes.
Ramírez-Backhaus M et al.·Actas Urol Esp
2015
Vitamin D opposes multilineage cell differentiation induced by Notch inhibition and BMP4 pathway activation in human colon organoids.
Bustamante-Madrid P et al.·Cell Death Dis
2024
Top 5 results · since 2015Search PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
KRT20-/SATB2+/MCPyV+ Sinonasal Merkel Cell Carcinoma: A Detailed Immunohistochemical and In Situ Hybridization Study.
Rocha GF et al.·Int J Surg Pathol
2025
Evaluation of IGF2, KRT14, and KRT20 as Urinary Biomarkers in Patients with Bladder Cancer.
Rasti A et al.·Rep Biochem Mol Biol
2023Cohort
Significance of Intraperitoneal-free KRT20 and CEACAM6 mRNA Expression for Peritoneal Recurrence of Gastric Cancer.
Kaku H et al.·Anticancer Res
2022
Decreased Plasma Level of Cytokeratin 20 (KRT20) Is Indicative of the Emergence and Severity of Acute GvHD Irrespective to the Type of Organ Involvement.
Lupsa N et al.·Biomedicines
2022Open Access
Supervised machine learning algorithm identified KRT20, BATF and TP63 as biologically relevant biomarkers for bladder biopsy specimens from interstitial cystitis/bladder pain syndrome patients.
Kamasako T et al.·Int J Urol
2022Cohort
Top 5 resultsSearch Europe PMC ↗
Full-Text Mentions
NLP-detected gene mentions in article bodies · via PubTator3
PubTator3
Identifying KRT20 as a Potential Key Gene in Lymphatic Metastasis of Head and Neck Squamous Cell Carcinoma
Zhang YF et al.·Technol Cancer Res Treat
2022
KRT20 Suppresses Exosomal Secretion of PRDX2 and Ferroptosis in Acute Kidney Injury.
Yin L et al.·J Am Soc Nephrol
2025
Identification of Novel Lung Cancer Driver Genes Connecting Different Omics Levels With a Heat Diffusion Algorithm
Yuan F et al.·Front Cell Dev Biol
2022
Integrated Analysis of Microarray Studies to Identify Novel Diagnostic Markers in Bladder Pain Syndrome/Interstitial Cystitis with Hunner Lesion
Cheng XF et al.·Int J Gen Med
2022
Association of immunohistochemical markers of tumor subtype with response to neoadjuvant chemotherapy and survival in patients with muscle-invasive bladder cancer
Razzaghdoust A et al.·Investig Clin Urol
2021Cohort
Top 5 full-text resultsSearch PubTator3 ↗

External Resources

Links to major genomics databases and tools

Franklin by Genoox
AI-powered variant curation and clinical analysis
DECIPHER
Genomic variants and phenotypes in rare disease patients