βThalassemia in Melanesia: Association With Malaria and Characterization of a Common Variant (IVS-1 nt 5 G→C)

Data on the distribution of β thalassemia among over 6,000 Melanesians reveals a major difference in the carrier rates between populations in the malarious coastal regions of New Guinea and those living in the historically malaria-free Highlands. The island of Maewo in Vanuatu has a particularly high incidence of β+thalassemia associated with a single restriction enzyme haplotype. Direct cloning into a plasmid vector and sequence analysis demonstrate that the mutation is a G to C transversion at position 5 of intron 1 of the β-globin gene. Oligonucleotide probe surveys indicate that this variant accounted for all cases of βthalassemia studied from Maewo. It is also common in coastal Papua New Guinea where haplotype and oligonucleotide probe data suggest that the molecular basis of βthalassmia is more heterogeneous.