Frequency of the CCR5-Δ32 mutation in the Atlantic island populadons of Madeira, the Azores, Cabo Verde, and Sao Tome e Principe

There is evidence that the CCR5-Delta 32 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 sub ' jected to positive selection, leading to a high frequency in Europe (approximate to 10%). We carried out the present study to determine the 32-bp deletion allele and genotype frequencies of the CCR5 gene (CCR5-Delta 32) in the Atlantic island populations of Madeira, the Azores, Cabo Verde, and Sao Tome e Principe. These Atlantic archipelagos were all colonized by the Portuguese in the 15th and 16th centuries, but the latter two received most of their settler; from the West African coast. The frequency of the CCR5-Delta 32 mutation varies between 0% in Sao Tome e Principe 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 (P < 0.05) between some of these populations, for example, between Sao Tome e Principe and Cabo Verde, and even within populations (e.g., Portugal, Madeira, and the Azores).