What Is FGF3? Definition and What Research Reports

Definition

FGF3 stands for fibroblast growth factor 3. The term refers to both a human gene, located on the long arm of chromosome 11 in the 11q13 region, and the secreted signalling protein that gene encodes. Like other members of the fibroblast growth factor family, the FGF3 protein is released by cells and binds fibroblast growth factor receptors (FGFRs) on neighbouring cells, where it influences processes such as cell proliferation, migration and tissue patterning during embryonic development. In the older literature the gene was described under the name int-2, reflecting how it was first mapped. FGF3 is therefore best understood as an endogenous developmental signalling molecule described in genetics and developmental biology, not as a compound with an established clinical use. This page is for educational purposes only and is not medical advice; consult a licensed physician or qualified clinician with any question about a health condition.

What Class of Molecule Is It?

FGF3 is a secreted polypeptide growth factor. It is synthesised from mRNA as a full-length protein with a signal sequence, processed through the secretory pathway, and acts extracellularly on receptor tyrosine kinases of the FGFR family. Because FGFR genes are alternatively spliced, individual FGFs show preference for particular receptor isoforms; FGF3 is described in the literature as a ligand for the "b" splice variants of FGFR1 and FGFR2, which are expressed largely in epithelial tissues. A 2025 developmental biology study examined early and transient requirements for FGFR2b/1b ligands — the group to which FGF3 belongs — during cochlear sensory and neural cell subtype differentiation, and reported that these ligand requirements fell within narrow developmental windows (PMID 40848747).

The wider fibroblast growth factor family has been organised into subfamilies on the basis of sequence similarity and gene structure. Comparative genomics work on FGF16 orthologs across vertebrate genomes illustrated this approach, aligning FGF genes between species to infer family relationships and conserved exon organisation (PMID 16211270).

Quick reference

How the Term Is Used in Peptide and Protein Research

FGF3 appears in the literature as a gene symbol, a transcript in sequencing datasets, and a protein in developmental signalling experiments. It is not a short synthetic peptide analogue of the kind that dominates much peptide-related discussion; it is a full-length secreted protein studied in cells, embryos and patient genomes. Three usages are common:

• As a developmental ligand. Studies of organ formation describe FGF3 alongside other FGFR2b/1b ligands when mapping which signals are required at which embryonic stage, as in cochlear differentiation work (PMID 40848747).
• As a candidate gene in human genetics. Sequencing studies of hearing loss and inner-ear malformation list FGF3 among genes screened for variants; researchers performing whole exome sequencing in patients with non-syndromic hearing loss reported candidate variants identified through that approach (PMID 38894825).
• As a locus in cancer genomics. The 11q13 region that contains FGF3 is recurrently amplified in several tumour types, so the gene symbol frequently appears in copy-number and regulatory-landscape analyses.

Because the FGF family contains members with very different biology, the number in the name matters. Metabolic FGFs are the subject of separate therapeutic research; a 2025 review of the treatment landscape for metabolic-dysfunction-associated steatotic liver disease surveyed the drug classes under investigation for that condition (PMID 40943823), a field distinct from the developmental biology in which FGF3 is usually discussed.

What the Published Literature Reports

Development of the inner ear and skull

The clearest body of work involving FGF3 concerns craniofacial and otic development. A 2025 study using human organoid models set out to validate gene variants linked to cochlear malformations and reported that organoids allowed rapid functional assessment of candidate variants (PMID 39786576). In a separate 2022 experiment, researchers targeting fibroblast growth factor receptors in zebrafish larvae reported severe craniofacial malformations following receptor inhibition (PMID 36444384). A 2019 review of animal models of craniosynostosis summarised the model systems used to study premature fusion of cranial sutures, a field in which FGF receptor signalling is a recurring theme (PMID 31563616).

Chromosome 11q13

Because FGF3 sits in a gene-dense stretch of 11q13, its symbol appears in descriptions of both deletions and amplifications of that region. A 2016 clinical review described chromosome 11q13 deletion syndrome and the phenotypic features associated with loss of material from that region (PMID 28018436). On the amplification side, a 2023 study performed functional screening of amplification outlier oncogenes in organoid models of early tumorigenesis and reported which amplified candidates conferred growth advantages in that system (PMID 37922313). A 2024 molecular study dissected a CTCF topological boundary and reported principles governing how enhancers engage neighbouring oncogenes when such boundaries are disrupted (PMID 38452764). Large-scale tumour sequencing has also mapped this territory: exome sequencing of hepatocellular carcinomas identified new mutational signatures and potential therapeutic targets, according to the 2015 study reporting that analysis (PMID 25822088).

Transcriptomic datasets

FGF-family transcripts, including FGF3, are routinely quantified in single-cell sequencing atlases rather than studied in isolation. As an example of the format, a 2022 single-cell RNA-sequencing study of dorsal root ganglion neurons in mice reported subtype-specific transcriptomic perturbations under a neuropathic pain condition (PMID 36264609). Findings from such datasets describe expression patterns in the model studied and do not by themselves establish a function for any single gene.

FGF3 in Humans: What Studies Report

FGF3 is not an approved drug and is not administered as a therapeutic in the studies listed here, so there is no clinical adverse-event profile for it in this evidence set. What the literature reports instead is phenotype associated with altered FGF signalling or altered gene dosage. The 2022 zebrafish experiment reported severe craniofacial malformations when fibroblast growth factor receptors were targeted in larvae (PMID 36444384), and the 2016 review described the clinical features catalogued in chromosome 11q13 deletion syndrome (PMID 28018436). Human genetic work in this area is diagnostic rather than interventional: whole exome sequencing in patients with non-syndromic hearing loss was used to identify candidate causative variants (PMID 38894825).

Limitations of the Current Evidence

1. Much of the mechanistic work sits in animal or organoid systems — zebrafish larvae (PMID 36444384) and human organoids (PMID 39786576) — and does not translate directly to human physiology.
2. Genomic association at 11q13 does not identify which gene in an amplified or deleted interval drives a phenotype, which is precisely why functional screens were developed in organoid models (PMID 37922313).
3. Developmental requirements can be narrow in time, as the cochlear study reported for FGFR2b/1b ligands (PMID 40848747), making results sensitive to the stage examined.

Nothing on this page describes an intervention, a protocol or a use in people. Readers with questions about genetic testing, hearing loss or any medical condition should raise them with a licensed physician.

References

• Early and transient requirements for FGFR2b/1b ligands in cochlear sensory and neural cell subtype differentiation (Developmental Biology, 2025)
• Human organoids for rapid validation of gene variants linked to cochlear malformations (Human Genetics, 2025)
• Whole Exome Sequencing of Non-Syndromic Hearing Loss Patients (Iranian Journal of Public Health, 2024)
• Targeting fibroblast growth factor receptors causes severe craniofacial malformations in zebrafish larvae (PeerJ, 2022)
• Animal models of craniosynostosis (Neuro-Chirurgie, 2019)
• Chromosome 11q13 deletion syndrome (Korean Journal of Pediatrics, 2016)
• Functional screening of amplification outlier oncogenes in organoid models of early tumorigenesis (Cell Reports, 2023)
• Dissection of a CTCF topological boundary uncovers principles of enhancer-oncogene regulation (Molecular Cell, 2024)
• Exome sequencing of hepatocellular carcinomas identifies new mutational signatures and potential therapeutic targets (Nature Genetics, 2015)
• scRNA-sequencing reveals subtype-specific transcriptomic perturbations in DRG neurons of Pirt(EGFPf) mice in neuropathic pain condition (eLife, 2022)
• Comparative genomics on FGF16 orthologs (International Journal of Molecular Medicine, 2005)
• Treatment Landscape of Metabolic-Dysfunction-Associated Steatotic Liver Disease (Journal of Clinical Medicine, 2025)