MT-CYB
Chr MTcytochrome b
Also known as: MTCYB
Cytochrome b is the only mitochondrial DNA-encoded subunit of Complex III of the respiratory chain, serving as the catalytic core for ubiquinol:cytochrome c oxidoreductase activity. Mutations cause Complex III deficiency presenting with exercise intolerance, cardiomyopathy, or MELAS-like syndrome. Inheritance is maternal through the mitochondrial genome, with phenotypic severity depending on the degree of heteroplasmy.
Definitive — sufficient evidence for diagnostic panels
Population Genetics & Constraint
Constraint data not available from gnomAD.
This gene has evidence for multiple mechanisms of pathogenicity (dominant-negative and gain-of-function). Both the Badonyi & Marsh prediction and the broader genomic evidence point to dominant-negative as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.
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
100 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories· variant type breakdown unavailable
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | — | — | — | — | 0 |
Likely Pathogenic | — | — | — | — | 0 |
VUS | — | — | — | — | 51 |
Likely Benign | — | — | — | — | 16 |
Benign | — | — | — | — | 33 |
| Total | — | 100 | |||
Counts from ClinVar esearch · Updated hourly
View in ClinVar →Protein Context — Lollipop Plot
MT-CYB · protein map & ClinVar variants
Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.
3D Protein StructureAlphaFold
External Resources
Links to major genomics databases and tools
Clinical Trials
Active and recruiting trials from ClinicalTrials.gov
pCCLCHIM-p47 (Lentiviral Vector Transduced CD34 Plus Cells) in Patients With p47 Autosomal Recessive Chronic Granulomatous Disease (AR-CGD)
ENROLLING BY INVITATIONLentiviral Gene Therapy for p47 AR-CGD
RECRUITINGExternal Resources
Links to major genomics databases and tools