Austronesian origin of the 27-bp deletion of the erythrocyte band 3 gene in East Sepik, Papua New Guinea inferred from mtDNA analysis.

ABSTRACT

The 27-bp deletion in the erythrocyte band 3 gene (B3Delta27) constitutes a genetic basis for Southeast Asian and Melanesian ovalocytosis. The distribution of B3Delta27 has been interpreted to reflect malaria selection or dispersal of the recent expansion of Austronesian-speaking populations. To explore these two hypotheses, we examined eight malarious populations of the East Sepik Province of Papua New Guinea (PNG) that speak both the Austronesian and Papuan languages. The B3Delta27 allele frequencies within populations were not positively correlated with malaria endemicities. In contrast, statistically significant geographical variations in the B3Delta27 allele distribution were observed. B3Delta27 was high (0.06-0.07) in the islands, intermediate (0.02-0.03) in coastal regions, but was absent or rare (0.00-0.01) in inland populations. Furthermore, the prevalence of the mitochondrial DNA region V 9-bp deletion, associated with the Austronesian expansion, was significantly correlated with that of B3Delta27. These results suggest that B3Delta27 was introduced by Austronesian-speaking people within the past 3,500 years and subsequently expanded to populations along the coasts and islands of PNG. This study highlights the contribution of population origins, patterns of gene flow, disease selection and genetic drift in determining the genetic compositions of present populations.