Different hypotheses can account for such elongated and divergent haplotype patterns. Indeed, the high levels of nucleotide identity between CD209 and CD209L could have led to gene conversion between the two genes, an event that would explain the outlier position of cluster A in the context of CD209 phylogeny. We reasoned that if gene conversion has occurred, we expect that the derived alleles distinguishing clusters A and B in CD209 would correspond to the allelic state observed in their homologous positions in CD209L. Of all positions, only four fit this criterion. In addition, these positions were not physically clustered, which therefore excludes a major gene-conversion event as the explanation of the divergent CD209 phylogeny.