TAP1

Chr 6AR

transporter 1, ATP binding cassette subfamily B member

Also known as: ABC17, ABCB2, APT1, D6S114E, MHC1D1, PSF-1, PSF1, RING4

NCBI Gene: 6890ENSG00000168394UniProt: Q03518

The membrane-associated protein encoded by this gene is a member of the superfamily of ATP-binding cassette (ABC) transporters. ABC proteins transport various molecules across extra- and intra-cellular membranes. ABC genes are divided into seven distinct subfamilies (ABC1, MDR/TAP, MRP, ALD, OABP, GCN20, White). This protein is a member of the MDR/TAP subfamily. Members of the MDR/TAP subfamily are involved in multidrug resistance. The protein encoded by this gene is involved in the pumping of degraded cytosolic peptides across the endoplasmic reticulum into the membrane-bound compartment where class I molecules assemble. Mutations in this gene may be associated with ankylosing spondylitis, insulin-dependent diabetes mellitus, and celiac disease. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2014]

Primary Disease Associations & Inheritance

MHC class I deficiency 1MIM #604571
AR
404
ClinVar variants
28
Pathogenic / LP
0.00
pLI score
1
Active trials
Clinical Summary— TAP1
🧬
Gene-Disease Validity (ClinGen)
MHC class I deficiency · ARDefinitive

Definitive — sufficient evidence for diagnostic panels

⚡
Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
📋
ClinVar Variants
28 Pathogenic / Likely Pathogenic· 173 VUS of 404 total submissions
💊
Clinical Trials
1 active or recruiting trial — potential therapeutic options may be available
Some data sources returned errors (1)

clinvar: Error: NCBI fetch failed: 429 https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi

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.
0.66LOEUF
pLI 0.000
Z-score 3.16
OE 0.43 (0.28–0.66)
Tolerant

Typical tolerance to LoF variation

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.
1.77Z-score
OE missense 0.76 (0.69–0.83)
327 obs / 430.0 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.0.43 (0.28–0.66)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.76 (0.69–0.83)
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.0.89
0≤1.21.6
LoF obs/exp: 15 / 35.2Missense obs/exp: 327 / 430.0Syn Z: 1.22

ClinVar Variant Classifications

404 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic25
Likely Pathogenic3
VUS173
Likely Benign192
Benign9
Conflicting2
25
Pathogenic
3
Likely Pathogenic
173
VUS
192
Likely Benign
9
Benign
2
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
9
0
16
0
25
Likely Pathogenic
2
0
1
0
3
VUS
0
140
33
0
173
Likely Benign
0
16
62
114
192
Benign
0
0
6
3
9
Conflicting
—2
Total11156118117404

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

View in ClinVar →

Protein Context — Lollipop Plot

TAP1 · protein map & ClinVar variants

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

Gene2Phenotype Curations

TAP1-related bare lymphocyte syndrome

strong
ARLoss Of FunctionAbsent Gene Product
Skin
G2P ↗

Gene2Phenotype curations · DECIPHER consortium patient cohort (public variants) · deciphergenomics.org

OMIM — Genotype-Phenotype Relationships

1 OMIM entry

OMIM

MHC class I deficiency 1

MIM #604571

Molecular basis of disorder known

Autosomal recessive
📖
GeneReview available — TAP1
Authoritative clinical overview · NCBI Bookshelf · Recommended first read
Open GeneReview ↗
Clinical Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
Atezolizumab with enzalutamide versus enzalutamide alone in metastatic castration-resistant prostate cancer: a randomized phase 3 trial.
Powles T et al.·Nat Med
2022Clinical trial
Reversible downregulation of HLA class I in adenoid cystic carcinoma.
Li A et al.·J Immunother Cancer
2025
IL-4 mediated TAP2 downregulation is a dominant and reversible mechanism of immune evasion and immunotherapy resistance in non-small cell lung cancer.
Ranjan K et al.·Mol Cancer
2025Functional
Antigen presentation deficiency, mesenchymal differentiation, and resistance to immunotherapy in the murine syngeneic CT2A tumor model.
Iorgulescu JB et al.·Front Immunol
2023Functional
Clinical efficacy and biomarker analysis of neoadjuvant camrelizumab plus chemotherapy for early-stage triple-negative breast cancer: a experimental single-arm phase II clinical trial pilot study.
Zheng C et al.·Int J Surg
2024Clinical trial
Clinical Significance of TAP1 and DLL4 Expression in Patients With Locally Advanced Gastric Cancer.
Segami K et al.·In Vivo
2021Cohort
Factors that increase class I MHC expression may contribute to the development of immune checkpoint inhibitor-induced diabetes.
Aizenbud L et al.·J Immunother Cancer
2025
Paradoxical Psoriasis in Patients Receiving Therapy with Tumor Necrosis Factor Inhibitors: Potential Pathogenic Mechanisms and the Role of Genetic Factors.
Costin D et al.·Int J Mol Sci
2024Review
Targeting EGFR-binding protein SLC7A11 enhancing antitumor immunity of T cells via inducing MHC-I antigen presentation in nasopharyngeal carcinoma.
Wang H et al.·Cell Death Dis
2025
Clinical and immunological spectrum of MHC class I deficiency: insights from a long-term cohort with two novel mutations.
Haskologlu S et al.·Front Immunol
2025Cohort
Top 10 resultsSearch PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
Top 5 resultsSearch Europe PMC ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov
Glioma

Clinical Study for the Safety and Therapeutic Efficacy of the AI-QMMM Designed TamavaqTM Personalised Vaccine in Patients With Newly Diagnosed Glioma.

RECRUITING
NCT07077616Phase EARLY_PHASE1Biogenea Pharmaceuticals Ltd.Started 2025-07-01
Biological: personalized vaccine Based on genetic and transcriptional sequencing information, personalized peptide vaccines would be designed and produced;

External Resources

Links to major genomics databases and tools