POR

Chr 7AR

cytochrome p450 oxidoreductase

Also known as: CPR, CYPOR, P450R

NCBI Gene: 5447ENSG00000127948UniProt: P16435

This gene encodes an endoplasmic reticulum membrane oxidoreductase that is essential for multiple metabolic processes, including reactions catalyzed by cytochrome P450 proteins for metabolism of steroid hormones, drugs and xenobiotics. The encoded protein has a flavin adenine dinucleotide (FAD)-binding domain and a flavodoxin-like domain which bind two cofactors, FAD and FMN, that allow it to donate electrons directly from NADPH to all microsomal P450 enzymes. Mutations in this gene cause a complex set of disorders, including apparent combined P450C17 and P450C21 deficiency, amenorrhea and disordered steroidogenesis, congenital adrenal hyperplasia and Antley-Bixler syndrome, that resemble those caused by defects in steroid metabolizing enzymes such as aromatase, 21-hydroxylase, and 17 alpha-hydroxylase. [provided by RefSeq, Aug 2020]

Primary Disease Associations & Inheritance

Antley-Bixler syndrome with genital anomalies and disordered steroidogenesisMIM #201750
AR
Disordered steroidogenesis due to cytochrome P450 oxidoreductaseMIM #613571
577
ClinVar variants
81
Pathogenic / LP
0.00
pLI score
6
Active trials
Clinical Summary— POR
🧬
Gene-Disease Validity (ClinGen)
Antley-Bixler syndrome with genital anomalies and disordered steroidogenesis · 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
81 Pathogenic / Likely Pathogenic· 143 VUS of 577 total submissions
💊
Clinical Trials
6 active or recruiting trials — potential therapeutic options may be available

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.
0.84LOEUF
pLI 0.000
Z-score 2.31
OE 0.58 (0.41–0.84)
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.
-0.07Z-score
OE missense 1.01 (0.93–1.09)
448 obs / 443.7 exp
Tolerant

Tolerant to missense variation

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.0.58 (0.41–0.84)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.1.01 (0.93–1.09)
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.1.06
0≤1.21.6
LoF obs/exp: 21 / 35.9Missense obs/exp: 448 / 443.7Syn Z: -0.67

ClinVar Variant Classifications

577 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic48
Likely Pathogenic33
VUS143
Likely Benign313
Benign8
Conflicting32
48
Pathogenic
33
Likely Pathogenic
143
VUS
313
Likely Benign
8
Benign
32
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
24
1
23
0
48
Likely Pathogenic
21
5
7
0
33
VUS
2
118
23
0
143
Likely Benign
1
1
133
178
313
Benign
0
0
6
2
8
Conflicting
—32
Total48125192180577

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

View in ClinVar →

Protein Context — Lollipop Plot

POR · 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

Antley-Bixler syndrome with genital anomalies and disordered steroidogenesis

MIM #201750

Molecular basis of disorder known

Autosomal recessive

Disordered steroidogenesis due to cytochrome P450 oxidoreductase

MIM #613571

Molecular basis of disorder known

Clinical Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
ESHRE consensus on the definition of 'poor response' to ovarian stimulation for in vitro fertilization: the Bologna criteria.
Ferraretti AP et al.·Hum Reprod
2011
Pretreatment with coenzyme Q10 improves ovarian response and embryo quality in low-prognosis young women with decreased ovarian reserve: a randomized controlled trial.
Xu Y et al.·Reprod Biol Endocrinol
2018
Diagnosis and treatment of gastroesophageal reflux disease: recommendations of the Asociación Mexicana de Gastroenterología.
Huerta-Iga F et al.·Rev Gastroenterol Mex
2016Review
TEAS, DHEA, CoQ10, and GH for poor ovarian response undergoing IVF-ET: a systematic review and network meta-analysis.
Zhu F et al.·Reprod Biol Endocrinol
2023Review
Fenotipos de la enfermedad por reflujo gastroesofágico: una visión basada en su fisiopatología.
Soto-Pérez JC et al.·Cir Cir
2023
Adjuvant treatment strategies in ovarian stimulation for poor responders undergoing IVF: a systematic review and network meta-analysis.
Zhang Y et al.·Hum Reprod Update
2020Review
Assessing the 5-year persistence in positive clinical response with innovative psoriasis treatments: a network meta-analysis of Psoriasis Area and Severity Index score.
Husein-ElAhmed H et al.·Clin Exp Dermatol
2024
Efficacy of intra-ovarian injection of autologous platelet-rich plasma in women with poor responders: a systematic review and meta-analysis.
Vahabi Dastjerdi M et al.·Arch Gynecol Obstet
2024Meta-analysis
MicroRNAs in POI, DOR and POR.
Luo J et al.·Arch Gynecol Obstet
2023Review
Practice-Oriented Research: An Introduction to New Developments and Future Directions.
Castonguay LG et al.·Adm Policy Ment Health
2024
Top 10 resultsSearch PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
[Multicomponent nurse-led intervention for the prevention of delirium in hospitalized frail older patients: PREDELENF study protocol].
Moreno-Moreno M et al.·Rev Esp Geriatr Gerontol
2026Cohort
[SEIOMM-SEMERGEN-semFYC-SEMG recommendations for the management of patients with osteoporosis/fragility fracture in primary care].
Carbonell-Abella C et al.·Aten Primaria
2026Cohort
Live Births Following IVF-FET in Two Adult Sisters with Nonclassic P450 Oxidoreductase Deficiency: A Case Report Identifying a Novel POR Variant.
Tian Y et al.·Int J Womens Health
2026Case report
[Hepatic encephalopathy from cholangitis in a young patient with ornithine transcarbamylase mutation].
Rojas-Salazar YL et al.·Rev Med Inst Mex Seguro Soc
2026
[Lower gastrointestinal bleeding secondary to Chronic Nonspecific Ulcerative Colitis: A clinical case].
Martínez-Cárdenas MÁ et al.·Rev Med Inst Mex Seguro Soc
2026
Top 5 resultsSearch Europe PMC ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov
Colorectal Cancer (CRC)MicrobiomeEarly Onset Colorectal Cancer

CARE-CRC: Microbiome Insights and Correlations for Risk and Outcomes in Colorectal Cancer

NOT YET RECRUITING
NCT06734156Gulbenkian Institute for Molecular MedicineStarted 2025-12-02
No intervention: observational study
Neuroendocrine NeoplasmNeuroendocrine Neoplasm of Gastrointestinal TractNeuroendocrine Neoplasm of Lung

Genetic Bases of Neuroendocrine Neoplasms in Mexican Patients

RECRUITING
NCT06523582Universidad Nacional Autonoma de MexicoStarted 2022-08-03
Neoplasms

A Study of Encorafenib Plus Cetuximab With or Without Chemotherapy in People With Previously Untreated Metastatic Colorectal Cancer

ACTIVE NOT RECRUITING
NCT04607421Phase PHASE3PfizerStarted 2020-12-21
EncorafenibCetuximabOxaliplatin
Increased Oocyte Deathin Vitro MaturationGREM1 Gene Mutation

GREM1, HAS2 and PTGS2 Gene Expression Following the in Vitro Maturation (IVM)

RECRUITING
NCT06315777Phase NANational University of MalaysiaStarted 2021-07-01
cumulus cell oocytes complex (COC) among women with poor ovarian reserve
Amyloidosis, Hereditary, Transthyretin-Related

Exercise in Hereditary ATTR (ATTRv) Amyloidosis

RECRUITING
NCT07033715Phase NAUniversity of MaiaStarted 2024-10-01
Exercise
Focal Dermal Hypoplasia (FDH)Goltz Syndrome

Study of Selected X-linked Disorders: Goltz Syndrome

ACTIVE NOT RECRUITING
NCT00691223Baylor College of MedicineStarted 2007-06

External Resources

Links to major genomics databases and tools