Frequency of the CCR5-Δ32 Mutation in the Atlantic Island Populations of Madeira, the Azores, Cabo Verde, and São Tomé e Príncipe

There is evidence that the CCR5-Δ32 mutation confers protection against HIV-1 infection to homozygous individuals. It is believed that this mutation spread through Europe with the Vikings and that it has been subjected to positive selection, leading to a high frequency in Europe (≈10%). We carried out the present study to determine the 32-bp deletion allele and genotype frequencies of the CCR5 gene (CCR5-Δ32) in the Atlantic island populations of Madeira, the Azores, Cabo Verde, and São Tomé e Príncipe. These Atlantic archipelagos were all colonized by the Portuguese in the 15th and 16th centuries, but the latter two received most of their settlers from the West African coast. The frequency of the CCR5-Δ32 mutation varies between 0% in São Tomé e Príncipe and 16.5% in the Azores. The Azores Islands have one of the highest frequencies of homozygotes found in Europe (4.8%). There are significant differences (