ESR1

Chr 6ADAR

estrogen receptor 1

Also known as: ER, ESR, ESRA, ESTRR, Era, NR3A1

This gene encodes an estrogen receptor and ligand-activated transcription factor. The canonical protein contains an N-terminal ligand-independent transactivation domain, a central DNA binding domain, a hinge domain, and a C-terminal ligand-dependent transactivation domain. The protein localizes to the nucleus where it may form either a homodimer or a heterodimer with estrogen receptor 2. The protein encoded by this gene regulates the transcription of many estrogen-inducible genes that play a role in growth, metabolism, sexual development, gestation, and other reproductive functions and is expressed in many non-reproductive tissues. The receptor encoded by this gene plays a key role in breast cancer, endometrial cancer, and osteoporosis. This gene is reported to have dozens of transcript variants due to the use of alternate promoters and alternative splicing, however, the full-length nature of many of these variants remain uncertain. [provided by RefSeq, Jul 2020]

Primary Disease Associations & Inheritance

{Migraine, susceptibility to}MIM #157300
AD
{Myocardial infarction, susceptibility to}MIM #608446
Breast cancer, somaticMIM #114480
Estrogen resistanceMIM #615363
AR
0
ClinVar variants
0
Pathogenic / LP
1.00
pLI score· haploinsufficient
12
Active trials
Clinical SummaryESR1
Population Constraint (gnomAD)
Highly constrained gene — heterozygous loss-of-function variants are very rare in the population (pLI 1.00). One damaged copy is likely sufficient to cause disease.
💊
Clinical Trials
12 active or recruiting trials — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

LoF intolerant — likely haploinsufficient
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.
0.19LOEUF
pLI 0.999
Z-score 4.45
OE 0.04 (0.010.19)
Highly constrained

Highly LoF-intolerant (top ~10% of genes)

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.
1.61Z-score
OE missense 0.75 (0.680.84)
258 obs / 341.9 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.0.04 (0.010.19)
00.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.75 (0.680.84)
00.61.4
Synonymous OE?Control metric — synonymous variants are largely neutral and expected near OE = 1.0. Significant deviation may indicate annotation issues.1.13
01.21.6
LoF obs/exp: 1 / 25.0Missense obs/exp: 258 / 341.9Syn Z: -1.24

ClinVar Variant Classifications

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

ESR1 · 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

{Migraine, susceptibility to}

MIM #157300

Molecular basis of disorder known

Autosomal dominant

{Myocardial infarction, susceptibility to}

MIM #608446

Molecular basis of disorder known

Breast cancer, somatic

MIM #114480

Molecular basis of disorder known

Estrogen resistance

MIM #615363

Molecular basis of disorder known

Autosomal recessive
Clinical Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
ESR1 mutations in breast cancer.
Dustin D et al.·Cancer
2019Review
Top 10 resultsSearch PubMed ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

HER2 Negative Breast Cancer

Impact of Omitting Chemo Based on Patient's Selection for ER-Positive, HER2-Negative Breast Cancer With Ribociclib and Endocrine Therapy

RECRUITING
NCT06953882Phase PHASE2Yale UniversityStarted 2025-07-09
Ribociclib 400mgLetrozole 2.5mgAnastrazole 1mg
Breast Cancer

Preoperative Fulvestrant With or Without Enzalutamide in ER+/Her2- Breast Cancer

ACTIVE NOT RECRUITING
NCT02955394Phase PHASE2University of Colorado, DenverStarted 2017-09-21
EnzalutamideFulvestrant
Breast Cancer

Higher Per Daily Treatment-Dose Radiation Therapy or Standard Per Daily Treatment Radiation Therapy in Treating Patients With Early-Stage Breast Cancer That Was Removed by Surgery

ACTIVE NOT RECRUITING
NCT01349322Phase PHASE3Radiation Therapy Oncology GroupStarted 2011-05-24
Standard fractionation whole breast irradiationHypofractionated whole breast irradiationConcurrent boost
Metastatic Breast Cancer

Patient-Centric Study to Assess the Impact of Genomic Profiling on the Treatment of Patients With Metastatic Breast Cancer in Spain

RECRUITING
NCT06991946SOLTI Breast Cancer Research GroupStarted 2025-05-20
Liquid BiopsyArchival Tumor DNA
Advanced Breast CancerER-positive Breast CancerHER2-negative Breast Cancer

Elacestrant + Everolimus in Patients ER+/HER2-, ESR1mut, Advanced Breast Cancer Progressing to ET and CDK4/6i.

ACTIVE NOT RECRUITING
NCT06382948Phase PHASE3MedSIRStarted 2024-12-05
EverolimusElacestrantPlacebo
Breast CancerInvasive Breast CancerCarcinoma in Situ of the Breast

Prospective Breast Cancer Biospecimen Collection

RECRUITING
NCT04074720Thomas Jefferson UniversityStarted 2018-05-10
Tissue Sample collectionBlood Sample CollectionRectal Swab
Breast AdenocarcinomaEstrogen Receptor- Negative Breast CancerEstrogen Receptor-positive Breast Cancer

Neoadjuvant Pembrolizumab + Decitabine Followed by Std Neoadj Chemo for Locally Advanced HER2- Breast Ca

ACTIVE NOT RECRUITING
NCT02957968Phase PHASE2Virginia Commonwealth UniversityStarted 2017-01-24
DoxorubicinCyclophosphamidePaclitaxel
Recurrent Breast CarcinomaStage III Breast Cancer AJCC v7Stage IIIA Breast Cancer AJCC v7

Tamoxifen Citrate or Z-Endoxifen Hydrochloride in Treating Patients With Locally Advanced or Metastatic, Estrogen Receptor-Positive, HER2-Negative Breast Cancer

ACTIVE NOT RECRUITING
NCT02311933Phase PHASE2National Cancer Institute (NCI)Started 2015-05-28
Endoxifen HydrochlorideLaboratory Biomarker AnalysisPharmacological Study
Stage I Breast CancerStage II Breast CancerStage III Breast Cancer

Niraparib + Dostarlimab In BRCA Mutated Breast Cancer

ACTIVE NOT RECRUITING
NCT04584255Phase PHASE2Dana-Farber Cancer InstituteStarted 2020-12-18
NiraparibDostarlimab
Estrogen Receptor-positive Breast CancerMusculoskeletal ComplicationsProgesterone Receptor-positive Breast Cancer

A Study to Evaluate Genetic Predictors of Aromatase Inhibitor Musculoskeletal Symptoms (AIMSS)

ACTIVE NOT RECRUITING
NCT01824836Phase NAECOG-ACRIN Cancer Research GroupStarted 2013-06-11
anastrozole
Breast Cancer

Evaluating the Addition of Adjuvant Chemotherapy to Ovarian Function Suppression Plus Endocrine Therapy in Premenopausal Patients With pN0-1, ER-Positive/HER2-Negative Breast Cancer and an Oncotype Recurrence Score Less Than or Equal to 25

RECRUITING
NCT05879926Phase PHASE3NRG OncologyStarted 2023-08-31
Ovarian Function Suppression + Aromatase InhibitorAdjuvant Chemotherapy + Ovarian Function Suppression
Breast Cancer

The T-REX Trial: Tailored Regional External Beam Radiotherapy in Clinically Node-negative Breast Cancer Patients With 1-2 Sentinel Node Macrometastases.

RECRUITING
NCT05634889Phase NARegion SkaneStarted 2023-03-17
De-escalation