Blood groups of Brazilian Indians (Carajás).

Abstract

THE Carajás Indians of Bananal Island, found by Golden1 to include 51 per cent of persons of group B, are exceptional among South American Indians, who all belong to group O. The late Dr. E. M. da Silva died while working among the Carajás. He found the following distribution, in 113 of them: Such an incidence is impossible; but it shows that the Carajás do not possess a high percentage of group B. Golden, as well as da Silva, used slide methods, which are not suitable for testing anæmic people. Last July one of us (P. C. J.) went to the Carajás village and bled sixty-six Indians. The tests were made in our laboratory in Rio de Janeiro for the following blood-group systems: ABO, Rh-Hr, MNS, P, Kell, Duffy, Lutheran and Lewis. The complete results will be published elsewhere, after we have tested larger numbers of people; but two points are of special interest. The first is that all sixty-six Indians tested with anti-A, anti-B and anti-AB sera, by the minimum volume technique, belonged to group O. Using slide tests, we obtained doubtful results with the same bloods. This probably accounts for Golden and da Silva's results. The second point is related to the Duffy system: among fifty-five Indians we found twenty-three Duffy positives. This observation seems important, since it is contrary to the results of Pantin and Junqueira2 among other Brazilian Indians, and it indicates a lower incidence than those obtained by Pantin and Kallsen3, and several others working on North American Indians.