We studied the possible effects of the expansion of ancient Mediterranean civilizations during the five centuries before and after Christ on the European distribution of the mutant allele for the chemokine receptor gene CCR5 which has a 32-bp deletion ( CCR5-Delta32 ) .
O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-GeneOrGeneProduct I-GeneOrGeneProduct O B-GeneOrGeneProduct O O O B-SequenceVariant I-SequenceVariant O I-SequenceVariant O O