A selective advantage for the Gerbich-negative phenotype in malarious areas of Papua New Guinea.

The Gerbich-negative phenotype occurs in about 10% of Melanesians living in the northern provinces of Papua New Guinea where malaria is endemic. The prevalence and severity of malaria was determined in 266 Melanesians of known Gerbich blood group status. P. falciparum and/or P. vivax infection in Gerbich-negative subjects was 5.7% compared with 18.6% in those who were Gerbich positive (p = 0.05), whereas P. malariae occurred at comparable rates in Gerbich-negative (8.6%) and Gerbich-positive subjects (8.2%). Gerbich-negative erythrocytes showed increased deformability compared with Gerbich-positive cells, suggesting at least one mechanism by which a selective advantage for the Gerbich-negative phenotype could be effected in malarious areas.