MT-CO2

Chr MT

cytochrome c oxidase subunit II

Also known as: COII, MTCO2

NCBI Gene: 4513 ENSG00000198712 UniProt: P00403 OMIM: 516040

This gene encodes cytochrome c oxidase subunit II, a core component of Complex IV of the mitochondrial respiratory chain that catalyzes the final step of electron transport and oxygen consumption. Mutations cause Complex IV deficiency presenting as encephalomyopathy with variable neurological manifestations including developmental delay, seizures, and progressive neurodegeneration. Inheritance is maternal through the mitochondrial genome, with clinical severity often correlating with the degree of heteroplasmy.

GeneReviews OMIM ResearchSummary from Curated mito context

Contributes to cytochrome-c oxidase activity. Predicted to be involved in mitochondrial electron transport, cytochrome c to oxygen and positive regulation of vasoconstriction. Located in mitochondrial inner membrane. Part of respiratory chain complex IV. Biomarker of Huntington's disease and stomach cancer. [provided by Alliance of Genome Resources, Jul 2025]

GeneReviews OMIM ResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

UniProtMitochondrial complex IV deficiency

Clinical highlights

Gene–disease validity (ClinGen)

Active trials

Pubs (1 yr)

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P/LP submissions

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P/LP missense

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LOEUF

Multiple*

Mechanism· predicted

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GeneReview available — MT-CO2

Authoritative clinical overview · Recommended first read

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Nuclear-gene analyses omitted

MT-CO2 is a mitochondrial protein-coding gene. gnomAD constraint, carrier burden and exome coverage, the ClinVar type breakdown, AlphaFold and transcript-architecture views are built for nuclear genes and are not shown. Population data for mtDNA variants (gnomAD v3.1, homoplasmy and heteroplasmy) is on each variant page.

Where it sits in the mitochondrial genome

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proteinrRNAtRNAouter ring H-strand · inner L-strandMITOMAP confirmedreported (as of 2026-10-07)

37 genes from Ensembl (rCRS numbering, matched to MITOMAP’s Gene Loci); landmarks and disease alleles from MITOMAP (CC BY 3.0). Circular layout after MitoWheel.

ClinVar Variant Classifications

0 submitted variants in ClinVar

ClinVar

Protein Context — Lollipop Plot

MT-CO2 · protein map & ClinVar variants

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

MITOMAP Disease Variants — MT-CO2

Live table ↗

Variant	AA	Disease	Status	GenBank seqs
m.7587T>C	M1T	Mitochondrial Encephalomyopathy	Likely pathogenic · confirmed	0
m.7598G>A	A5T	Possible LHON helper variant	Reported	695
m.7623C>T	T13I	LHON	Reported	0
m.7630T>-	frameshift	MELAS	Reported	0
m.7637G>A	E18K	PD risk factor / neurological impairment	Uncertain significance · reported	2
m.7671T>A	M29K	MM	Uncertain significance · reported	0
m.7695T>C	L37P	Cerebellar and pyramidal syndrome with cognitive impairment	Reported	0
m.7697G>A	V38I	Possible HCM susceptibility, high altitude adaptation	Reported	315
m.7706G>A	A41T	Alpers-Huttenlocher-like	Reported	12
m.7749T>C	I55T	Possible association with sepsis	Reported	2
m.7859G>A	D92N	Progressive Encephalomyopathy	Reported	187
m.7868C>T	L95F	LHON	Reported	14
m.7877A>C	K98Q	PEG glaucoma	Reported	0
m.7887G>A	G101D	Cerebellar ataxia + neuropathy + exercise intolerance	Reported	0
m.7896G>A	W104Term	Multisystem Disorder	Pathogenic · confirmed	0
m.7943T>C	S120P	Possible association with sepsis	Reported	0
m.7965T>C	F127S	Hepatic failure / COX deficiency	Reported	1
m.7970G>T	E129Term	Encephalopathy	Reported	0
m.7989T>C	L135P	Rhabdomyolysis	Uncertain significance · reported	0
m.8010T>C	V142A	Developmental delay, ataxia, seizure, hypotonia, lactic acidosis	Reported	4
m.8021A>G	I146V	Asthenozoospermia	Reported	4
m.8024G>A	E147K	Bioenergetic deficiency with optic atrophy	Reported	1
m.8042AT>-	frameshift	Lactic Acidosis	Uncertain significance · reported	0
m.8078G>A	V165I	DEAF	Reported	33
m.8088T>-	frameshift	Mitochondrial myopathy with complex IV deficiency	Likely pathogenic · confirmed	0
m.8108A>G	I175V	SNHL	Reported	79
m.8119T>-	frameshift	Biliary atresia	Reported	0
m.8156G>-	frameshift	Multi-system mitochondrial disorder	Reported	0
m.8163A>G	Y193C	Late-onset cerebellar ataxia	Reported	0
m.8231C>A	L216M	Coronary artery disease risk factor	Reported	0
m.8241T>G	F219C	MIDD+retinopathy	Conflicting reports	0
m.8249G>A	G222Term	Mitochondrial myopathy	Reported	0