CYB561

Chr 17AR

cytochrome b561

Also known as: CGCytb, CYB561A1, FRRS2, ORTHYP2

NCBI Gene: 1534ENSG00000008283UniProt: P49447

Predicted to enable transmembrane monodehydroascorbate reductase activity. Predicted to be involved in ascorbate homeostasis. Predicted to be located in chromaffin granule membrane. Predicted to be active in lysosomal membrane. [provided by Alliance of Genome Resources, Jul 2025]

Primary Disease Associations & Inheritance

Orthostatic hypotension 2MIM #618182
AR
0
Active trials
12
Pathogenic / LP
55
ClinVar variants
2
Pubs (1 yr)
1.0
Missense Z
0.54
LOEUF
Clinical Summary— CYB561
⚡
Population Constraint (gnomAD)
Moderately constrained gene (pLI 0.61) — some intolerance to loss-of-function variants.
📋
ClinVar Variants
12 Pathogenic / Likely Pathogenic· 35 VUS of 55 total submissions

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
Moderate LoF intolerance
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.
0.54LOEUF
pLI 0.611
Z-score 2.61
OE 0.17 (0.07–0.54)
Moderately constrained

More LoF-intolerant than ~75% 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.
0.95Z-score
OE missense 0.79 (0.69–0.92)
132 obs / 166.5 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.0.17 (0.07–0.54)
0≤0.351.4
Missense OE?Ratio of observed to expected missense variants. OE ≤ 0.6 = fewer missense variants than expected by chance.0.79 (0.69–0.92)
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.0.98
0≤1.21.6
LoF obs/exp: 2 / 11.6Missense obs/exp: 132 / 166.5Syn Z: 0.16
DN
0.6356th %ile
GOF
0.6442th %ile
LOF
0.3454th %ile

This gene has evidence for multiple mechanisms of pathogenicity (gain-of-function and dominant-negative). Both the Badonyi & Marsh prediction and the broader genomic evidence point to gain-of-function as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.

GOFprediction above median
DNprediction above median

Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.

Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.

ClinVar Variant Classifications

55 submitted variants in ClinVar

ClinVar

Classification Summary

Pathogenic12
VUS35
Likely Benign6
Benign2
12
Pathogenic
35
VUS
6
Likely Benign
2
Benign

Curated Variants Distribution

Classified variants from ClinVar · 5 ACMG categories

ClassificationLoFMissense + InframeNon-codingSynonymousTotal
Pathogenic
0
1
11
0
12
Likely Pathogenic
0
0
0
0
0
VUS
0
33
2
0
35
Likely Benign
0
1
0
5
6
Benign
0
0
1
1
2
Total03514655

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

View in ClinVar →

Protein Context — Lollipop Plot

CYB561 · protein map & ClinVar variants

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

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
Full-Text Mentions
NLP-detected gene mentions in article bodies · via PubTator3
PubTator3
Top 5 full-text resultsSearch PubTator3 ↗
Key Publications
Landmark & review papers · by relevance
PubMed
Top 5 results · since 2015Search PubMed ↗
Recent Gene-Specific Literature
Gene in title · MEDLINE · newest first
Europe PMC
Top 5 resultsSearch Europe PMC ↗

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