Overview
CCR5 encodes a receptor on the surface of white blood cells (specifically T cells). This receptor regulates the migration of immune cells into inflamed tissue. It became famous primarily because it serves as a co-receptor that HIV viruses require to enter human cells.
3p21.31 (Chromosome 3)
Immune System
Autosomal recessive (for resistance)
~1% of Europeans are homozygous (resistant)
Function & Significance
The CCR5 receptor is a chemokine receptor that receives signals to guide immune cells to sites of inflammation. While it plays an important role in defending against certain infections, many HIV strains (R5-tropic) use it as an “anchor point” to attach to the cell.
💡 The Delta32 Mutation
Approximately 1,000 to 3,000 years ago, a mutation emerged in Northern Europe: a deletion of 32 base pairs in the CCR5 gene. People who have two copies of this mutation (homozygous) do not form a functional CCR5 receptor on the cell surface and are therefore largely resistant to HIV infection.
🧬 Relevant SNP: rs333
This famous SNP (actually an InDel variant) describes the CCR5-Delta32 mutation:
3:46373452
/
Interpretation:
I/I: Normal CCR5 expression. Normal risk of HIV infection.
I/D: Partial protection. The disease progression in AIDS can be significantly slowed down.
D/D: Complete “knockout” of the receptor. Widespread resistance to common HIV strains.
⚠️ Other Risks
Resistance to HIV comes at a price: carriers of the Delta32 mutation have a slightly increased risk for severe cases of West Nile Virus and TBE (Tick-borne encephalitis), as the CCR5 receptor is needed for the defense against these viruses in the brain.
📚 Data Sources
- OMIM: #601373 – Chemokine, CC Motif, Receptor 5; CCR5
- dbSNP: rs333
- PubMed: “CCR5-delta32 and HIV resistance”
Biological Function
Associated Conditions
Analyzed Markers
Delta32 (32-bp Deletion) - Carriers of two deletion alleles (D/D) are largely resistant to infection with R5-tropic HIV-1 strains. Heterozygous carriers often have a slower disease progression.