CCR5 distribution

A gene variant CCR5-Delta32, so-called because 32 DNA base pairs are missing gives some people some resistance to HIV infection and take longer to develope AIDS.

The variant is in about 15% of people in some northern European areas,whereas less than 4% of Greeks have the variant.

The frequency of the gene variant follows the changing boundaries of the Roman Empire 500BC-500 AD.

One theory is that the Romans brought with them disease-carrying mosquitoes, which reduced CCR5-Delta32 frequency,modern carriers of the variant are more susceptible to West Nile Fever.