Blood groups, serum proteins and hemoglobins of Brazilian Tiriyo Indians.

A population living in the border of Brazil and Surinam was studied with regard to 21 genetic markers from 13 independent systems. No marked heterogeneity was observed among this group and two others from the same tribe investigated by other researchers. The frequencies of genes LMs, Fy& and Hp1 are in the upper third of the distribution range observed among South American Indians; those for fil and fiz are in the middle, while LMS, LNS, LNs, fi2, Dia, and especially P1 and Gc2 present low values. All individuals were apparently homozygous for genes к , Tf ' HbA, AlA, and lacked WVa. Some evidence was obtained of limited admixture but for the most part this population appears to retain an unmodified Amerindian gene pool. The Tiriyo Indians (called Trio in Surinam) speak a Carib language and presently number some 800 individuals who live in the savannahs of the Brazil-Surinam border. Their population seems to have remained stable and relatively isolated during the last 70 years. Figueiredo (1963) gives a useful summary about the situation of the group living in Brazil; general information about the Surinam populations can be found in Colson ( 1971 ) . A detailed demographic study of the Brazilian Tiriyo was undertaken by Frikel and Cortez (1972); Frikel (1970, 1971) analyzed the situation of the Kaxuyana, a Carib group who now lives with and has intercrossed with the Tiriyo in Brazil, examining also the acculturation process to which both tribes have been submitted in the past 10 years. 1 Departamento de Genetica, Instituto de Biociencias, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil. 2 Department of Epidemiology and Public Health, Yale University, New Haven, Connecticut. 3 Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan. 4 Present address: Division of Genetics, Department of Anatomy, University of Rochester School of Medicine and Dentistry, Rochester. New York. Human Biology , February 1974 , Vol. 46, No. I, pp. 81-87. © Wayne State University Press , 1974 This content downloaded from 207.46. 13.51 on Tue, 21 Jun 2016 06:05:18 UTC All use subject to http://about.jstor. org/terms 82 F. M. Salzano et al. Few biological investigations of the Tiriyo have been performed up to the present time. Van Loghem et al. (1969), Glanville and Geerdink (1969, 1970), and Geerdink et al. (1973) studied the Gm and Inv types, blood groups, dermatoglyphics, skinfold thickness and other body measurements of individuals from the Surinam groups; the latter were also subjected to a series of medical and epidemiological observations by Schaad (1960), and Glanville and Geerdink (1972). Black et al. (1969, 1970), on the other hand, studied the prevalence of antibodies against viruses and the measles vaccine reactions of the Tiriyo living in Brazil. The present communication furnishes data on 21 genetic markers from 13 independent systems obtained among these Indians and tries to relate them to these previous findings. Materials and Methods The Brazilian Tiriyo live around a Franciscan mission located at the margins of the river Paru de Oeste (1°57'N, 55°49^). The group is relatively isolated, since access by land is made difficult by the forest and many rapids of the rivers. Flights into the mission occur about once a month, but are restricted to members of the Brazilian Air Force or authorized persons. The Tiriyo have traditionally traded with the Bush Negroes of Surinam, but these contacts have decreased in recent years. The unusually low rate of serologic reactions against several of the common acute viral infections observed among them (Black et al. 1970) provides another indication of their isolation. Consanguineous marriages are frequent among the Tiriyo; their fertility and mortality are moderate and within levels found previously in groups living at this cultural stage (Frikel and Cortez, 1972). Also present at the mission are some Kaxuyana and Ewarhoyana, descendants of what seem to have been two other Carib tribes. Since, however, their number is small and they have crossed in the past and continue to intermarry with the Tiriyo, results concerning all of them were pooled in a single sample. Blood collections were made on two occasions, in 1966 and 1970. The sera from the first excursion were separated in Belem, Brazil and kept frozen there until they were transported under refrigeration to Porto Alegre and Ann Arbor. In the latter city they were studied for haptoglobin, Gc, transferrin and albumin types, the techniques used being those described by Weitkamp et al. (1972). Specimens from the 1970 trip were collected in 10 ml vacutainers with ACD and sent This content downloaded from 207.46. 13.51 on Tue, 21 Jun 2016 06:05:18 UTC All use subject to http://about.jstor. org/terms Genetic Polymorphisms in Tiny о Indians 83 by air in an ice box to Porto Alegre, where they arrived one week afterwards. There they were tested for blood groups, hemoglobin, haptoglobin and albumin types with methods already described elsewhere (Salzano, 1964; Salzano and Tondo, 1968; Schwantes et al. 1967; Weitkamp et al. 1967). Results and Discussion Tables 1 and 2 show the phenotypes observed in the several genetic systems studied, the corresponding gene frequencies being presented