Immunoglobulin allotypes in Sardinia.

1218 individuals from Sardinia island (Italy) were tested for Gm and Km markers; 10 were not tested for Gm and only 401 were typed for Am markers. The peculiar genetic makeup of the Sardinian population is confirmed by their Gm allotypes. Their differences from those found in a control population of continental Italy (Ferrara), suggest ancient contacts with the Middle East and Africa. An indication for such contacts may also be found in the striking presence of the haplotype Gm f;n;bsc5, a haplotype not previously found in a human population. A significant difference of G2m(n) allotype was observed between highland and lowland regions. If confirmed, it may suggest an adaptive pressure related to the CH2 region of the gamma2 chain, possibly due to endemic malaria in the past.