DEFB4A
Defensin Beta 4A: Antimicrobial Peptide in Innate Immunity
Gene Information Card
| Symbol | DEFB4A |
|---|---|
| Full Name | Defensin Beta 4A |
| Gene Type | protein-coding |
| Chromosomal Location | 8p23.1 |
| NCBI Gene ID | 1673 ncbi.nlm.nih.gov/gene/1673 |
| Ensembl ID | ENSG00000171791 |
| UniProt ID | O15263 |
| OMIM ID | 602215 |
| HGNC ID | 2767 |
| Aliases | DEFB4, DEFB104, DEFB-4, HBD-2, BD-2, SAP1 |
Description
DEFB4A encodes beta-defensin 4A (also known as human beta-defensin 2, hBD-2), a cysteine-rich cationic antimicrobial peptide produced by epithelial cells. It plays a key role in innate immunity by disrupting microbial membranes and is induced by inflammatory stimuli such as cytokines and bacterial products.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Psoriasis | Overexpression of DEFB4A in keratinocytes contributes to chronic inflammation and antimicrobial defense | ClinVar, OMIM |
| Atopic dermatitis | Reduced DEFB4A expression linked to increased susceptibility to skin infections | NCBI Gene, OMIM |
| Cystic fibrosis | Impaired DEFB4A activity in airway epithelium may contribute to chronic bacterial colonization | NCBI Gene |
| Inflammatory bowel disease | Altered DEFB4A expression in colonic epithelium associated with mucosal inflammation | NCBI Gene |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skin | 12.5 | Medium |
| Lung | 8.3 | Low |
| Tonsil | 15.1 | Medium |
| Salivary gland | 6.7 | Low |
| Esophagus | 9.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HaCaT (keratinocyte) | 18.4 | Induced by IL-1β and TNF-α |
| A549 (lung epithelial) | 7.9 | Basal expression |
| Caco-2 (intestinal epithelial) | 5.6 | Low basal expression |
| THP-1 (monocyte) | 2.1 | Very low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| rs1800972 (c.5'UTR variant) | SNP | 0.15 (global) | May alter expression levels; associated with infection susceptibility |
| rs11362 (c.5'UTR variant) | SNP | 0.20 (global) | Linked to altered DEFB4A expression in skin |
Mutation functional classification
Loss of Function (LOF)
Not reported for DEFB4A; copy number variation may reduce expression.
Gain of Function (GOF)
Increased copy number associated with elevated expression in psoriasis.
Dominant Negative (DN)
Not described.
View complete mutation data：
Gene Ontology (GO)
| • defense response to bacterium | • innate immune response |
| • membrane disruption | • antimicrobial humoral response |
| • extracellular region |
Pathways
• Innate Immune System (Reactome R-HSA-168249)
• Antimicrobial peptides (Reactome R-HSA-6803157)
Protein Summary
Beta-defensin 4A is a 41-amino acid secreted peptide with three disulfide bonds. It exhibits broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and enveloped viruses. Expression is induced by pro-inflammatory cytokines and bacterial components via NF-κB and MAPK pathways.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| DEFB4A Knockout HEK293 Cell Line | EDJ-KQ50235 | Human | 1673 | Details Get a Quote |
| DEFB4A Knockout HeLa Cell Line | EDJ-KQ53087 | Human | 1673 | Details Get a Quote |
| DEFB4A Knockout A-549 Cell Line | EDJ-KQ61553 | Human | 1673 | Details Get a Quote |
| DEFB4A Knockout HCT 116 Cell Line | EDJ-KQ70045 | Human | 1673 | Details Get a Quote |
