COX4I1

Chr 16AR

cytochrome c oxidase subunit 4I1

Also known as: COX IV-1, COX4, COX4-1, COXIV, COXIV-1, MC4DN16

COX4I1 encodes subunit IV isoform 1 of cytochrome c oxidase (complex IV), the terminal enzyme of the mitochondrial electron transport chain that reduces oxygen to water and contributes to ATP production through oxidative phosphorylation. Mutations cause mitochondrial complex IV deficiency, nuclear type 16, which follows autosomal recessive inheritance. This gene has a relatively low constraint against loss-of-function variants (pLI 0.39, LOEUF 0.68), suggesting some tolerance to heterozygous loss of function.

OMIMResearchSummary from RefSeq, OMIM, UniProt
DNmechanismARLOEUF 0.681 OMIM phenotype
Clinical SummaryCOX4I1
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Gene-Disease Validity (ClinGen)
Leigh syndrome · ARLimited

Limited evidence — not for standalone diagnostic reporting

2 total gene-disease associations curated

Population Constraint (gnomAD)
Constrained for loss-of-function variants (OE-LoF 0.22) despite low pLI — interpret in context.
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Clinical Trials
1 active or recruiting trial — potential therapeutic options may be available

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

Tolerant — LoF & missense variants common in population
LoF Constraint
0.68LOEUF
pLI 0.394
Z-score 2.21
OE 0.22 (0.090.68)
Tolerant

Typical tolerance to LoF variation

Missense Constraint
-0.17Z-score
OE missense 1.05 (0.901.23)
112 obs / 106.9 exp
Tolerant

Tolerant to missense variation

Observed / Expected Ratios
LoF OE0.22 (0.090.68)
00.351.4
Missense OE1.05 (0.901.23)
00.61.4
Synonymous OE1.11
01.21.6
LoF obs/exp: 2 / 9.3Missense obs/exp: 112 / 106.9Syn Z: -0.54
DN
0.6453th %ile
GOF
0.4282th %ile
LOF
0.3358th %ile

The highest-scoring mechanism for this gene is dominant-negative.

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

0 submitted variants in ClinVar

Protein Context — Lollipop Plot

COX4I1 · protein map & ClinVar variants

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

3D Protein StructureAlphaFold
Clinical Literature
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