Free for academic non-profit institutions. Other users need a Commercial license

Aliases for TNXB Gene

Aliases for TNXB Gene

  • Tenascin XB 2 3 5
  • Hexabrachion-Like Protein 3 4
  • TNXB1 3 4
  • TNXB2 3 4
  • HXBL 3 4
  • TN-X 3 4
  • TNX 3 4
  • XB 3 4
  • Growth-Inhibiting Protein 45 3
  • Tenascin XB1 3
  • Tenascin XB2 3
  • Tenascin-X 3
  • EDSCLL 3
  • TNXBS 3
  • EDS3 3
  • TENX 3
  • VUR8 3
  • XBS 3

External Ids for TNXB Gene

Previous HGNC Symbols for TNXB Gene

  • TNXB1
  • TNXB2

Previous GeneCards Identifiers for TNXB Gene

  • GC06M032037
  • GC06M031779
  • GC06M032080
  • GC06M032085
  • GC06M032116
  • GC06M032087
  • GC06M032089
  • GC06M032091
  • GC06M032093
  • GC06M032095
  • GC06M032097
  • GC06M031976
  • GC06M032008

Summaries for TNXB Gene

Entrez Gene Summary for TNXB Gene

  • This gene encodes a member of the tenascin family of extracellular matrix glycoproteins. The tenascins have anti-adhesive effects, as opposed to fibronectin which is adhesive. This protein is thought to function in matrix maturation during wound healing, and its deficiency has been associated with the connective tissue disorder Ehlers-Danlos syndrome. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. It is one of four genes in this cluster which have been duplicated. The duplicated copy of this gene is incomplete and is a pseudogene which is transcribed but does not encode a protein. The structure of this gene is unusual in that it overlaps the CREBL1 and CYP21A2 genes at its 5' and 3' ends, respectively. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2008]

GeneCards Summary for TNXB Gene

TNXB (Tenascin XB) is a Protein Coding gene. Diseases associated with TNXB include Ehlers-Danlos Syndrome, Classic-Like and Vesicoureteral Reflux 8. Among its related pathways are ECM proteoglycans and PI3K-Akt signaling pathway. Gene Ontology (GO) annotations related to this gene include heparin binding and collagen binding. An important paralog of this gene is TNC.

UniProtKB/Swiss-Prot for TNXB Gene

  • Appears to mediate interactions between cells and the extracellular matrix. Substrate-adhesion molecule that appears to inhibit cell migration. Accelerates collagen fibril formation. May play a role in supporting the growth of epithelial tumors.

Gene Wiki entry for TNXB Gene

Additional gene information for TNXB Gene

No data available for CIViC summary , Tocris Summary , PharmGKB "VIP" Summary , fRNAdb sequence ontologies and piRNA Summary for TNXB Gene

Genomics for TNXB Gene

GeneHancer (GH) Regulatory Elements for TNXB Gene

Promoters and enhancers for TNXB Gene
GeneHancer (GH) Identifier GH Type GH
GH Sources Gene Association Score Total Score TSS distance (kb) Number of Genes Away Size (kb) Transcription Factor
Binding Sites
Gene Targets
GH06I032106 Promoter/Enhancer 2 EPDnew FANTOM5 Ensembl ENCODE dbSUPER 559.1 +4.1 4082 9.7 PKNOX1 GATA2 E2F8 ARID2 ZNF143 FOS ZNF263 SP3 RXRA REST TNXB C4A HLA-DRB1 ATF6B SKIV2L STK19 TNXA AGER CYP21A1P STK19B
GH06I032045 Promoter/Enhancer 1.9 EPDnew Ensembl ENCODE dbSUPER 550.2 +68.1 68082 3.1 HDGF PKNOX1 ZFP64 ARID4B DMAP1 ZNF2 SLC30A9 ZNF143 FOS MXD4 TNXB C4A CYP21A1P TNXA CYP21A2 RNA5SP206
GH06I032175 Promoter/Enhancer 2.3 EPDnew Ensembl ENCODE dbSUPER 34.8 -62.4 -62426 5.1 DMAP1 YBX1 YY1 E2F8 ZNF143 ZNF548 SP3 NFYC GLIS1 NR2C1 RNF5 AGPAT1 BRD2 LSM2 LY6G5B DDX39B ATF6B GPANK1 VARS BAG6
GH06I032965 Promoter/Enhancer 2.4 EPDnew Ensembl ENCODE dbSUPER 31.6 -855.3 -855335 10.4 ZFP64 DMAP1 IRF4 YY1 SLC30A9 ZNF213 E2F8 ZNF143 ZNF548 ZNF263 BRD2 HLA-DMA ENSG00000223837 LEMD2 VPS52 RXRB ATF6B DAXX HCG25 RING1
GH06I032126 Promoter/Enhancer 2.1 EPDnew Ensembl ENCODE 34.3 -13.8 -13759 4.5 CLOCK ZFP64 DMAP1 YY1 SLC30A9 E2F8 ZNF143 ZNF548 SP3 NFYC ATF6B FKBPL TNXB VARS PPT2 BRD2 C4A LSM2 GPANK1 BAG6
- Elite GeneHancer and/or Elite GeneHancer-gene association Download GeneHancer data dump

GeneHancers around TNXB on UCSC Golden Path with GeneCards custom track

Top Transcription factor binding sites by QIAGEN in the TNXB gene promoter:

Genomic Locations for TNXB Gene

Genomic Locations for TNXB Gene
74,181 bases
Minus strand

Genomic View for TNXB Gene

Genes around TNXB on UCSC Golden Path with GeneCards custom track

Cytogenetic band:
TNXB Gene in genomic location: bands according to Ensembl, locations according to GeneLoc (and/or Entrez Gene and/or Ensembl if different)
Genomic Location for TNXB Gene
GeneLoc Logo Genomic Neighborhood Exon StructureGene Density

Proteins for TNXB Gene

  • Protein details for TNXB Gene (UniProtKB/Swiss-Prot)

    Protein Symbol:
    Recommended name:
    Protein Accession:
    Secondary Accessions:
    • P78530
    • P78531
    • Q08424
    • Q08AM0
    • Q08AM1
    • Q59GU7
    • Q5SQD3
    • Q5ST74
    • Q7L8Q4
    • Q8N4R1
    • Q9NPK9
    • Q9UC10
    • Q9UC11
    • Q9UC12
    • Q9UC13
    • Q9UMG7

    Protein attributes for TNXB Gene

    4242 amino acids
    Molecular mass:
    458220 Da
    Quaternary structure:
    • Homotrimer. Interacts with type I, III and V collagens and tropoelastin via its 29th fibronectin type-III domain.
    • Sequence=AAB47488.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=AAB67981.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305}; Sequence=CAB89296.1; Type=Erroneous gene model prediction; Evidence={ECO:0000305};

    Three dimensional structures from OCA and Proteopedia for TNXB Gene

    Alternative splice isoforms for TNXB Gene


neXtProt entry for TNXB Gene

Post-translational modifications for TNXB Gene

  • Glycosylation at isoforms=3, 431, isoforms=3, 4, 23853, posLast=39063906, posLast=39183918, and posLast=40934093

Other Protein References for TNXB Gene

Antibody Products

  • Abcam antibodies for TNXB

No data available for DME Specific Peptides for TNXB Gene

Domains & Families for TNXB Gene

Gene Families for TNXB Gene

Human Protein Atlas (HPA):
  • Disease related genes
  • Plasma proteins
  • Predicted intracellular proteins
  • Predicted secreted proteins

Suggested Antigen Peptide Sequences for TNXB Gene

Graphical View of Domain Structure for InterPro Entry



  • Belongs to the tenascin family.
  • Belongs to the tenascin family.
genes like me logo Genes that share domains with TNXB: view

Function for TNXB Gene

Molecular function for TNXB Gene

UniProtKB/Swiss-Prot Function:
Appears to mediate interactions between cells and the extracellular matrix. Substrate-adhesion molecule that appears to inhibit cell migration. Accelerates collagen fibril formation. May play a role in supporting the growth of epithelial tumors.

Phenotypes From GWAS Catalog for TNXB Gene

Gene Ontology (GO) - Molecular Function for TNXB Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0005178 integrin binding ISS --
GO:0005515 protein binding IPI 21516116
GO:0008201 heparin binding ISS --
genes like me logo Genes that share ontologies with TNXB: view
genes like me logo Genes that share phenotypes with TNXB: view

Human Phenotype Ontology for TNXB Gene

HPO Id HPO Name Alternative Ids Definition Synonyms

Animal Models for TNXB Gene

MGI Knock Outs for TNXB:

miRNA for TNXB Gene

miRTarBase miRNAs that target TNXB

Clone Products

No data available for Enzyme Numbers (IUBMB) , Transcription Factor Targets and HOMER Transcription for TNXB Gene

Localization for TNXB Gene

Subcellular locations from UniProtKB/Swiss-Prot for TNXB Gene

Secreted, extracellular space, extracellular matrix.

Subcellular locations from

Extracellular space Cytosol Plasma membrane Cytoskeleton Lysosome Endosome Peroxisome ER Golgi Apparatus Nucleus Mitochondrion 0 1 2 3 4 5 Confidence
COMPARTMENTS Subcellular localization image for TNXB gene
Compartment Confidence
extracellular 5
plasma membrane 2
cytoskeleton 2
peroxisome 1
endoplasmic reticulum 1
lysosome 1
golgi apparatus 1

Gene Ontology (GO) - Cellular Components for TNXB Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0005576 extracellular region IDA 27068509
GO:0005578 proteinaceous extracellular matrix IEA,NAS 7686164
GO:0005583 colocalizes_with fibrillar collagen trimer IDA 16278880
GO:0005615 extracellular space IDA 20551380
GO:0005622 intracellular IDA 15102077
genes like me logo Genes that share ontologies with TNXB: view

No data available for Subcellular locations from the Human Protein Atlas (HPA) for TNXB Gene

Pathways & Interactions for TNXB Gene

genes like me logo Genes that share pathways with TNXB: view

Gene Ontology (GO) - Biological Process for TNXB Gene

GO ID Qualified GO term Evidence PubMed IDs
GO:0007155 cell adhesion ISS --
GO:0030036 actin cytoskeleton organization ISS --
GO:0030198 extracellular matrix organization IEA --
GO:0030199 collagen fibril organization IEA --
GO:0032963 collagen metabolic process IMP 15102077
genes like me logo Genes that share ontologies with TNXB: view

No data available for SIGNOR curated interactions for TNXB Gene

Drugs & Compounds for TNXB Gene

(2) Drugs for TNXB Gene - From: Novoseek

Name Status Disease Links Group Role Mechanism of Action Clinical Trials

(2) Additional Compounds for TNXB Gene - From: Novoseek

Name Synonyms Role CAS Number PubChem IDs PubMed IDs
genes like me logo Genes that share compounds with TNXB: view

Transcripts for TNXB Gene

Unigene Clusters for TNXB Gene

Tenascin XB:
Representative Sequences:

Clone Products

Alternative Splicing Database (ASD) splice patterns (SP) for TNXB Gene

No ASD Table

Relevant External Links for TNXB Gene

GeneLoc Exon Structure for
ECgene alternative splicing isoforms for

Expression for TNXB Gene

mRNA expression in normal human tissues from GTEx, Illumina, BioGPS, and CGAP SAGE for TNXB Gene

mRNA expression in embryonic tissues and stem cells from LifeMap Discovery

Protein differential expression in normal tissues from HIPED for TNXB Gene

This gene is overexpressed in Uterus (10.3) and Serum (8.5).

Integrated Proteomics: protein expression in normal tissues and cell lines from ProteomicsDB, PaxDb, and MOPED for TNXB Gene

Protein tissue co-expression partners for TNXB Gene

- Elite partner

NURSA nuclear receptor signaling pathways regulating expression of TNXB Gene:


SOURCE GeneReport for Unigene cluster for TNXB Gene:


mRNA Expression by UniProt/SwissProt for TNXB Gene:

Tissue specificity: Highly expressed in fetal adrenal, in fetal testis, fetal smooth, striated and cardiac muscle. Isoform XB-short is only expressed in the adrenal gland.

Evidence on tissue expression from TISSUES for TNXB Gene

  • Adrenal gland(4.6)
  • Liver(4.5)
  • Blood(4.3)
  • Nervous system(4.2)
  • Bone marrow(4)
  • Heart(2.9)
  • Lung(2.4)
  • Gall bladder(2.3)
  • Intestine(2.3)

Phenotype-based relationships between genes and organs from Gene ORGANizer for TNXB Gene

Germ Layers:
  • ectoderm
  • endoderm
  • mesoderm
  • cardiovascular
  • digestive
  • immune
  • integumentary
  • nervous
  • reproductive
  • respiratory
  • skeletal muscle
  • skeleton
  • urinary
Head and neck:
  • brain
  • ear
  • head
  • jaw
  • mandible
  • maxilla
  • mouth
  • neck
  • pharynx
  • skull
  • chest wall
  • clavicle
  • diaphragm
  • esophagus
  • heart
  • heart valve
  • rib
  • rib cage
  • scapula
  • sternum
  • intestine
  • kidney
  • large intestine
  • small intestine
  • stomach
  • pelvis
  • placenta
  • rectum
  • ureter
  • urethra
  • urinary bladder
  • uterus
  • vulva
  • ankle
  • arm
  • digit
  • elbow
  • femur
  • fibula
  • finger
  • foot
  • forearm
  • hand
  • hip
  • humerus
  • knee
  • lower limb
  • radius
  • shin
  • shoulder
  • thigh
  • tibia
  • toe
  • ulna
  • upper limb
  • wrist
  • blood
  • blood vessel
  • peripheral nerve
  • peripheral nervous system
  • skin
  • spinal column
  • vertebrae
  • white blood cell
genes like me logo Genes that share expression patterns with TNXB: view

No data available for mRNA differential expression in normal tissues for TNXB Gene

Orthologs for TNXB Gene

This gene was present in the common ancestor of animals.

Orthologs for TNXB Gene

Organism Taxonomy Gene Similarity Type Details
(Pan troglodytes)
Mammalia TNXB 33 34
  • 98.5 (n)
(Canis familiaris)
Mammalia TNXB 33 34
  • 77.84 (n)
(Bos Taurus)
Mammalia TNXB 33 34
  • 74.44 (n)
(Mus musculus)
Mammalia Tnxb 33 16 34
  • 72.2 (n)
(Ornithorhynchus anatinus)
Mammalia -- 34
  • 29 (a)
(Monodelphis domestica)
Mammalia TNXB 34
  • 12 (a)
(Gallus gallus)
Aves CDD 34
  • 24 (a)
(Anolis carolinensis)
Reptilia TNXB 34
  • 10 (a)
tropical clawed frog
(Silurana tropicalis)
Amphibia tnxb 33
  • 50.5 (n)
African clawed frog
(Xenopus laevis)
Amphibia Xl.12557 33
(Danio rerio)
Actinopterygii TNXB 34
  • 10 (a)
Dr.18547 33
fruit fly
(Drosophila melanogaster)
Insecta sca 35 34
  • 38 (a)
BG:DS00180.14 35
  • 27 (a)
sea squirt
(Ciona savignyi)
Ascidiacea -- 34
  • 27 (a)
Species where no ortholog for TNXB was found in the sources mined by GeneCards:
  • A. gosspyii yeast (Ashbya gossypii)
  • Actinobacteria (Mycobacterium tuberculosis)
  • African malaria mosquito (Anopheles gambiae)
  • Alicante grape (Vitis vinifera)
  • alpha proteobacteria (Wolbachia pipientis)
  • amoeba (Dictyostelium discoideum)
  • Archea (Pyrococcus horikoshii)
  • baker's yeast (Saccharomyces cerevisiae)
  • barley (Hordeum vulgare)
  • beta proteobacteria (Neisseria meningitidis)
  • bread mold (Neurospora crassa)
  • Chromalveolata (Phytophthora infestans)
  • common water flea (Daphnia pulex)
  • corn (Zea mays)
  • E. coli (Escherichia coli)
  • filamentous fungi (Aspergillus nidulans)
  • Firmicute bacteria (Streptococcus pneumoniae)
  • fission yeast (Schizosaccharomyces pombe)
  • green algae (Chlamydomonas reinhardtii)
  • honey bee (Apis mellifera)
  • K. lactis yeast (Kluyveromyces lactis)
  • loblloly pine (Pinus taeda)
  • malaria parasite (Plasmodium falciparum)
  • medicago trunc (Medicago Truncatula)
  • moss (Physcomitrella patens)
  • orangutan (Pongo pygmaeus)
  • pig (Sus scrofa)
  • rainbow trout (Oncorhynchus mykiss)
  • rat (Rattus norvegicus)
  • rice (Oryza sativa)
  • rice blast fungus (Magnaporthe grisea)
  • schistosome parasite (Schistosoma mansoni)
  • sea anemone (Nematostella vectensis)
  • sea urchin (Strongylocentrotus purpuratus)
  • sorghum (Sorghum bicolor)
  • soybean (Glycine max)
  • stem rust fungus (Puccinia graminis)
  • sugarcane (Saccharum officinarum)
  • thale cress (Arabidopsis thaliana)
  • tomato (Lycopersicon esculentum)
  • toxoplasmosis (Toxoplasma gondii)
  • Trichoplax (Trichoplax adhaerens)
  • wheat (Triticum aestivum)
  • worm (Caenorhabditis elegans)

Evolution for TNXB Gene

Gene Tree for TNXB (if available)
Gene Tree for TNXB (if available)

Paralogs for TNXB Gene

Variants for TNXB Gene

Sequence variations from dbSNP and Humsavar for TNXB Gene

SNP ID Clin Chr 06 pos Variation AA Info Type
rs11752495 benign, likely-benign, not specified, not provided 32,062,138(-) G/T genic_upstream_transcript_variant, intron_variant
rs121912575 pathogenic, uncertain-significance, Ehlers-Danlos-like syndrome due to tenascin-X deficiency, not specified 32,084,536(-) C/T coding_sequence_variant, genic_upstream_transcript_variant, missense_variant
rs140770834 benign, likely-benign, not specified, not provided 32,064,851(-) C/A/G/T coding_sequence_variant, genic_upstream_transcript_variant, missense_variant
rs144556766 pathogenic, Ehlers-Danlos-like syndrome due to tenascin-X deficiency 32,095,736(-) ACACACACACAC/ACACACACAC/ACACACACACACAC coding_sequence_variant, frameshift, genic_upstream_transcript_variant
rs150379644 likely-benign, uncertain-significance, not specified, not provided 32,067,653(-) A/T genic_upstream_transcript_variant, intron_variant

Structural Variations from Database of Genomic Variants (DGV) for TNXB Gene

Variant ID Type Subtype PubMed ID
nsv981129 CNV duplication 23825009
nsv969381 CNV duplication 23825009
nsv950155 CNV deletion 24416366
nsv830629 CNV loss 17160897
nsv823508 CNV gain 20364138
nsv823507 CNV loss 20364138
nsv819957 CNV loss 19587683
nsv602104 CNV loss 21841781
nsv602103 CNV loss 21841781
nsv602102 CNV gain 21841781
nsv602101 CNV loss 21841781
nsv602100 CNV loss 21841781
nsv602098 CNV gain 21841781
nsv602072 CNV loss 21841781
nsv602056 CNV loss 21841781
nsv602051 CNV loss 21841781
nsv602050 CNV loss 21841781
nsv602045 CNV gain 21841781
nsv601971 CNV gain 21841781
nsv5248 CNV insertion 18451855
nsv5247 CNV deletion 18451855
nsv428141 CNV gain+loss 18775914
nsv285 CNV deletion 15895083
nsv284 CNV deletion 15895083
nsv1126749 CNV deletion 24896259
nsv1112900 CNV deletion 24896259
nsv10825 CNV loss 18304495
nsv10824 CNV gain+loss 18304495
nsv1073969 CNV deletion 25765185
nsv1028506 CNV gain 25217958
nsv1020992 CNV gain 25217958
esv3890827 CNV gain+loss 25118596
esv3890825 CNV loss 25118596
esv3890824 CNV loss 25118596
esv3608576 CNV loss 21293372
esv3608575 CNV loss 21293372
esv3423416 CNV duplication 20981092
esv3413736 CNV duplication 20981092
esv3370311 CNV duplication 20981092
esv3350929 CNV duplication 20981092
esv28110 CNV gain+loss 19812545
esv2759415 CNV gain+loss 17122850
esv2731825 CNV deletion 23290073
dgv20n31 CNV gain 19718026
dgv1099e199 CNV deletion 23128226
dgv10482n54 CNV loss 21841781
dgv10479n54 CNV loss 21841781
dgv10478n54 CNV loss 21841781
dgv10477n54 CNV loss 21841781
dgv10476n54 CNV loss 21841781
dgv10475n54 CNV loss 21841781
dgv10474n54 CNV gain 21841781
dgv10472n54 CNV loss 21841781
dgv10468n54 CNV loss 21841781
dgv10466n54 CNV loss 21841781
dgv10463n54 CNV loss 21841781
dgv10404n54 CNV loss 21841781
dgv10403n54 CNV loss 21841781

Variation tolerance for TNXB Gene

Gene Damage Index Score: 28.29; 99.85% of all genes are more intolerant (likely to be disease-causing)

Additional Variant Information for TNXB Gene

Human Gene Mutation Database (HGMD)
SNPedia medical, phenotypic, and genealogical associations of SNPs for

No data available for Polymorphic Variants from UniProtKB/Swiss-Prot for TNXB Gene

Disorders for TNXB Gene

MalaCards: The human disease database

(10) MalaCards diseases for TNXB Gene - From: HGMD, OMIM, ClinVar, GTR, Orphanet, Swiss-Prot, DISEASES, Novoseek, and GeneCards

- elite association - COSMIC cancer census association via MalaCards
Search TNXB in MalaCards View complete list of genes associated with diseases


  • Ehlers-Danlos syndrome due to tenascin X deficiency (EDSTNXD) [MIM:606408]: An Ehlers-Danlos-like syndrome characterized by hyperextensible skin, hypermobile joints, and tissue fragility. Tenascin-X-deficient patients, however, lack atrophic scars, a major diagnostic criteria for classic Ehlers-Danlos. Delayed wound healing, which is also common in classic EDS, is only present in a subset of patients. {ECO:0000269 PubMed:11642233, ECO:0000269 PubMed:15733269, ECO:0000269 PubMed:23768946}. Note=The disease is caused by mutations affecting the gene represented in this entry.
  • Vesicoureteral reflux 8 (VUR8) [MIM:615963]: A disease belonging to the group of congenital anomalies of the kidney and urinary tract. It is characterized by the reflux of urine from the bladder into the ureters and sometimes into the kidneys, and is a risk factor for urinary tract infections. Primary disease results from a developmental defect of the ureterovesical junction. In combination with intrarenal reflux, the resulting inflammatory reaction may result in renal injury or scarring, also called reflux nephropathy. Extensive renal scarring impairs renal function and may predispose patients to hypertension, proteinuria, renal insufficiency and end-stage renal disease. {ECO:0000269 PubMed:23620400}. Note=The disease is caused by mutations affecting the gene represented in this entry.

Additional Disease Information for TNXB

Genetic Association Database
Human Genome Epidemiology Navigator
ATLAS of Genetics and Cytogenetics in Oncology and Haematology
genes like me logo Genes that share disorders with TNXB: view

No data available for Genatlas for TNXB Gene

Publications for TNXB Gene

  1. Sequences promoting the transcription of the human XA gene overlapping P450c21A correctly predict the presence of a novel, adrenal-specific, truncated form of tenascin-X. (PMID: 8530023) Tee MK … Miller WL (Genomics 1995) 2 3 4 22 58
  2. Identification and characterization of multiple species of tenascin-X in human serum. (PMID: 17263730) Egging DF … Schalkwijk J (The FEBS journal 2007) 3 4 22 58
  3. Interactions of human tenascin-X domains with dermal extracellular matrix molecules. (PMID: 17033827) Egging D … Schalkwijk J (Archives of dermatological research 2007) 3 4 22 58
  4. Elastic fiber abnormalities in hypermobility type Ehlers-Danlos syndrome patients with tenascin-X mutations. (PMID: 15733269) Zweers MC … Schalkwijk J (Clinical genetics 2005) 3 4 22 58
  5. Lack of a genetic association between the TNXB locus and schizophrenia in a Chinese population. (PMID: 14729256) Liu LL … Hemmings GP (Neuroscience letters 2004) 3 22 44 58

Products for TNXB Gene

Sources for TNXB Gene