CYB5R4

Chr 6

cytochrome b5 reductase 4

Also known as: NCB5OR, cb5/cb5R, dJ676J13.1

NCBI Gene: 51167ENSG00000065615UniProt: Q7L1T6

NCB5OR is a flavohemoprotein that contains functional domains found in both cytochrome b5 (CYB5A; MIM 613218) and CYB5 reductase (CYB5R3; MIM 613213) (Zhu et al., 1999 [PubMed 10611283]).[supplied by OMIM, Jan 2010]

111
ClinVar variants
13
Pathogenic / LP
0.00
pLI score
0
Active trials
Clinical Summary— CYB5R4
⚡
Population Constraint (gnomAD)
Low constraint (pLI 0.00) — loss-of-function variants are relatively tolerated in the population.
📋
ClinVar Variants
13 Pathogenic / Likely Pathogenic· 93 VUS of 111 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.
0.94LOEUF
pLI 0.000
Z-score 1.80
OE 0.63 (0.44–0.94)
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.
0.74Z-score
OE missense 0.87 (0.78–0.97)
224 obs / 257.4 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.0.63 (0.44–0.94)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.87 (0.78–0.97)
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.1.01
0≤1.21.6
LoF obs/exp: 18 / 28.4Missense obs/exp: 224 / 257.4Syn Z: -0.04

ClinVar Variant Classifications

111 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic13
VUS93
Likely Benign3
Benign1
Conflicting1
13
Pathogenic
93
VUS
3
Likely Benign
1
Benign
1
Conflicting

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
0
13
0
13
Likely Pathogenic
0
0
0
0
0
VUS
1
74
18
0
93
Likely Benign
0
3
0
0
3
Benign
0
1
0
0
1
Conflicting
—1
Total178310111

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

View in ClinVar →

Protein Context — Lollipop Plot

CYB5R4 · 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 Literature
Landmark / reviewRecent case evidence
Key Publications
Landmark & review papers · by relevance
PubMed
Top 10 resultsSearch PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
CYB5R4 Gene Methylation as a Potential Epigenetic Marker for Ovarian Cancer.
Gonc A et al.·Clin Med Insights Oncol
2025🔓 Open Access
Top 5 resultsSearch Europe PMC ↗

Clinical Trials

Active and recruiting trials from ClinicalTrials.gov

ClinicalTrials.gov

No active trials found for this gene.

Search ClinicalTrials.gov →

External Resources

Links to major genomics databases and tools