CYB5B

protein-coding

cytochrome b5 type B

Gene summary

Enables heme binding activity. Contributes to nitrite reductase (NO-forming) activity. Involved in nitric oxide biosynthetic process. Located in membrane. Part of nitric-oxide synthase complex. [provided by Alliance of Genome Resources, Jul 2025]

MANE transcript

NM_030579.3

Inheritance

—

ClinVar variants

U:37

Top phenotype

—

gnomAD constraint

pLI —, LoF o/e 0.34

Max pathogenic AF

—

Genomic locus

chr16:69,398,402-69,466,264

External References & Databases

Ensembl (ENSG00000103018)

Transcript & Mutation Effects

hg38 • Region Span ~67.9 kb

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GenCC Phenotypes & Disease Associations

Curated gene-disease validity assertions and inheritance patterns

No GenCC data available for this gene.

ClinVar Associated Diseases & Phenotypes

Reported disease conditions connected to CYB5B variants in ClinVar

1 Conditions Cataloged

not specifiedTotal: 29

ClinVar Variants & Pathogenicity by Type

Statistics based on transcript NM_030579.3. Only rare variants are included.

We include only reliable ClinVar variants with their consequences to MANE Select, MANE Plus Clinical transcripts, or transcripts with TSL equal to 1. Click a count to filter the variants table below.

Slight differences between displayed counts and ClinVar may occur due to a different transcript/consequence chosen by our variant effect predictor, or because we classify Benign/Likely benign as Likely benign and Pathogenic/Likely pathogenic as Likely pathogenic.

Effect	PathogenicP	Likely pathogenicLP	VUS	Likely benignLB	BenignB	Sum
synonymous						0
missense			30 clinvar			30
nonsense						0
start loss						0
frameshift						0
splice donor/acceptor (+/-2bp)			7 clinvar			7
Total	0	0	37	0	0	37

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Transcript Catalog

Annotated transcript isoforms across RefSeq and Ensembl databases

Showing 4 of 30 transcripts

Transcript ID	Source	Protein ID	Coding Exons	MANE Status
NM_030579.3	RefSeq	NP_085056.2	5	MANE Select
ENST00000307892.13	Ensembl	ENSP00000308430.8	5	MANE Select
ENST00000515314.7	Ensembl	ENSP00000421492.3	4	Standard
ENST00000515314.8	Ensembl	ENSP00000421492.3	4	Standard

Gene Ontology (GO) Annotations & Pathways

Biological processes, molecular functions, cellular components and pathways

Pathways ConsensusPathDB

Oxidation by Cytochrome P450
Phase I - Functionalization of compounds
Biological oxidations
Metabolism

Biological Process

oxidation-reduction process

Molecular Function

protein binding
heme binding
metal ion binding

Cellular Component

mitochondrial outer membrane
membrane
integral component of membrane

gnomAD Constraint

Source: gnomAD

Gene type: protein_coding
Transcript type: protein_coding
Transcript: ENST00000307892
Coding exons: 5
Length: 41742
Individuals with no LoFs: 124785
Homozygous LoFs: 0
Heterozygous LoFs: 6
Defined: 124791
p: 0.0000240

	Z-Score	Observed	Expected	Observed/Expected	Mutation Rate	Total Possible
Missense	-0.208	85	79.8	1.07	0.00000383	963
Missense (PolyPhen)		6	14.108	0.42529		192
Synonymous	0.669	26	30.7	0.846	0.00000152	282
Loss of Function	1.81	3	8.81	0.341	3.71e-7	108

Population LoF Frequency

Population	CAF	p-value	Status
African	0	0.0	absent
Latino/Admixed American	0.00012	0.00012	rare
Ashkenazi Jewish	0	0.0	absent
East Asian	0	0.0	absent
Finnish	0	0.0	absent
European (Non-Finnish)	0.000018	0.000018	rare
South Asian	0	0.0	absent
Other	0	0.0	absent

dbNSFP Gene Annotations

Source: dbNSFP

Function: FUNCTION: Cytochrome b5 is a membrane bound hemoprotein which function as an electron carrier for several membrane bound oxygenases. {ECO:0000250}.;

Recessive Scores

pRec: 0.108

Intolerance Scores

LoFtool: 0.277
RVIS EVS: -0.21
RVIS percentile EVS: 38.28

Essentials

Essential (CRISPR): E
Essential (CRISPR2): S
Indispensability pred.: E
Indispensability score: 0.992

Gene Damage Prediction

	All	Recessive	Dominant
Mendelian	Medium	Medium	Medium
Primary Immunodeficiency	Medium	Medium	Medium
Cancer	Medium	Medium	Medium