AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 65:243-247 (1984) Erythrocyte and HLA Antigens of Atacamefio Indians FRANCISCO ROTHHAMMER, H. WERNER GOEDDE, ELENA LLOP, MONICA ACUNA, AND PATRICIA CARVAJAL Department of Cellular Biology and Genetics (RR., E.L., M.A.), Department ofDermatology (t?C.), Faculty of Medicine, University of Chile, Casilla IOD, Santiago, Chile, and Institute o f Human Genetics, University of Hamburg, Hamburg R R. G. (H. W.G.) K E Y WORDS Atacameiios Blood groups, Andean populations of Chile, ABSTRACT The present study reports the results of erythrocyte antigen typing for the following systems: ABO, MN, Rh, Kell, Duffy, and Diego in roughly 180 Atacamefio Indians from the oasis of Toconao, northern Chile. A subsample was tested for variation at the histocompatibility loci A, B, and C. Results agree with previous findings based on smaller samples. Caucasian admixture of the Atacameiios from Toconao was estimated to be 0.056 & 0.022. As part of a broader study whose general aims are to quantify the participation of evolutionary factors in the microdifferentiation of Andean aborigines and to assess their genetic response to drugs and environmental agents, the population of the oasis of Toconao in the Atacama desert was surveyed in March of 1983. The Atacama desert is located in northern Chile between lat. 19 S and lat. 27 S. Only one permanent river, the Loa, reaches the Pacific Ocean in this area, which is supposed to be one of the driest deserts on earth. The western slopes of the Andes are bare t o about 2.500 m. In the lower mountain region a few oases have been inhabited by men for at least 10,000 years, as judged by archaeological findings (Bittmann et al., 1978). The Atacameiios’ cultural elaboration began at about the start of the Christian era. Subsequently, they received the influences of the highland cultures of Tiwanaku around 600 AD and Inca at 1400 AD. The area was invaded by the Spanish in 1536, first under the command of Diego de Almagro, and 4 years later under Pedro de Valdivia and Francisco de Aguirre. The Spanish conquest was consolidated in 1557 through a treaty (Hidalgo, 1981). Toconao, located a t 2,500 m of altitude, was founded in 1557 by Juan Velasquez Altamirano, but archaeological evidence indicated that the oasis has been inhabited since prehistoric times (Hidalgo, 1981). The Atacame- 0 1984 ALAN R. LISS, INC. iios were originally Kunza speakers, a language classified by Greenberg (1956) in the Paezan subfamily of the Macro-Chibchan linguistic family and by Loukotka (1957) among the languages of the Andean tribes together with Aymara, Diaguita, and Mapuche, among others. The object of this report is to present the results of erythrocyte and HLA antigen typing. Other communications will be devoted to the analysis of the genetic response to drugs and environmental agents (Goedde et al., 1984a), the typification of erythrocyte enzymes and serum proteins (Goedde et al. N.D. 1984b), and sanitary aspects (Castillo et al., 1584). POPULATIONS AND METHODS The oasis of Toconao has 441 inhabitants according to the 1980 National Census. Of these, 206 are males and 235 females. The sample obtained by us comprised 182 individuals. Fifty-five percent of these were born in the same oasis, the remaining in the hamlets of Socaire (17%), Peine (9%), Talabre (7%), and Camar (6%) located in the immediate proximity of Toconao. Six percent of sampled individuals were born in San Pedro, 50 km north of Toconao, a somewhat larger village, which is the center of the civil adminstration. Received September 7, 1983; revised June 25, 1984; accepted July 3, 1984. 244 F. ROTHHAMMER ET AL By means of a sterile syringe, 20 ml of blood was obtained from volunteers by arm venipuncture. Three milliliters of blood with ACD as preservative was used for blood group determinations and 8 ml with heparin as anticoagulant for HLA typing. The remaining 9 ml was employed for enzyme electrophoresis. Antigenic specificities were determined for the following systems: ABO, Rh, MN, Duffy, Diego, and Kell. All determinations were carried out in tubes with 2% red cell suspensions using Biotest-Serum-Institut Gmbh., Offenbach, F.R.G. sera. The white cells of a subsample of 21 supposedly unrelated individuals were separated and tested for HLA antigenic specificity using the Biotest microtray Lymphotype ABC-60 with the NIH two stage citotoxicity test in the field, some 5 hours after the blood samples were obtained. Eight specificites of the A series, sixteen of the B series, and five of the C series are included in the Biotest microtray. On the average, more than one serum is provided for each specificity. Maximum likelihood gene frequency estimates were obtained using the MAXLIK computer program of Reed and Schull(l968). parture of the phenotype frequencies from Hardy-Weinberg equilibrium was analyzed using the chi-square test. A significant deficiency in the observed proportion of heterozygotes was observed for the MN system (x2 = 5.07; p < 0.05). The gene frequency estimates are shown in Tables 3 and 4. DISCUSSION The Atacameiios have been the object of previous communications (Etcheverry et al., 1967; Matson et al., 1967; Van der Does et al., 1972,1978). Our blood group findings are in general agreement with the results of Etcheverry et al. (1967) and Matson et al. (1967) based on substantially smaller samples. Van der Does et al. (1972)in a survey of the Atacameiio village of Socaire, located in the proximities of Toconao, reported higher frequencies of the K , Fya and Dia genes. Unfortunately, these authors called the subjects of their study Aymara, causing some confusion in the specialized literature. TABLE 2. HLA Phenotype frequencies in Atacamerio Indians RESULTS Tables 1 and 2 illustrate absolute and relative erythrocyte and HLA antigen phenotype frequencies of the Atacameiios. The de- Phenotypes A TABLE 1. Erythrocyte antigen phenotypes in A tacamerio Indians Phenotypes A B AB 0 MM MN NN CCDEE CCDEe CCDee CcDEE CcDEe CcDee ccDEE ccDEe ccDee K+ KFy (a+b-) Fy ( a + b + ) Fy (a-b+) Fy(a-b-) Di (a+) Di (a-) Observed numbers Observed proportions 20 0.110 0.005 0.000 0.885 0.433 0.389 0.178 0.000 0.033 0.199 0.055 0.458 0.061 0.166 0.028 0.000 0.000 1.000 0.628 0.267 0.105 0.000 0.016 0.984 1 0 161 78 70 32 0 6 36 10 83 11 30 5 0 0 182 113 48 19 0 3 179 1 2 3 9 10 11 w 19 B 28 Blank 5 7 8 12 13 14 15 16 17 18 C w 21 w22 27 w35 37 40 Blank w1 w2 w3 w4 w5 Blank Observed numbers Observed proportions 3 16 1 4 0 0 16 0 0 1 0 0 0 1 0.1428 0.7619 0.0476 0.1905 0.0000 4 14 1 0 0 0 0 0 5 0 5 0 9 2 0 5 0 7 0.0000 0.7619 0.0000 0.0000 0.0476 0.0000 0.0000 0.0000 0.0476 0.1905 0.6667 0.0476 0.0000 0.0000 0.0000 0.0000 0.0000 0.2381 0.0000 0.2381 0.0000 0.4286 0.0952 0.0000 0.2381 0.0000 0.3333 ERYTHROCYTE AND HLA ANTIGENS TABLE 3. Erythrocyte antigen gene frequencies in Atacameiio Indians Genes A B 0 M N CDE (RZ) CDe (R’) cDE (R2) cDe (Ro) cde (r) K ~k FYa FYb FY Dia Dib Estimated freauencv Standard error 0.0565 0.0027 0.9407 0.6278 0.3722 0.0465 0.4727 0.4340 0.0267 0,0198 0.0000 1.0000 0.7008 0.2158 0.0832 0.0082 0.9917 0.0123 0.0274 0.0125 0.0255 0.0255 0.0113 0.0263 0.0261 0.0343 0.0340 0.0000 0.0000 0.0322 0.0227 0.0292 0.0047 0.0047 TABLE 4. H L A gene frequencies in Atacameiio Indians 1 2 3 9 w 19 Blank 5 13 14 15 16 w35 40 Blank w1 w2 w2 Blank Estimated frequency Standard error 0.0714 0.4047 0.0237 0.0952 0.4048 0.0000 0.0255 0.0238 0.1070 0.3990 0.0238 0.1256 0.1328 0.1622 0.2431 0.0495 0.1259 0.5813 0.0397 0.0757 0.0252 0.0453 0.0757 0.0000 0.0245 0.0244 0.0501 0.0859 0.0257 0.0561 0.0583 0.0759 0.0711 0.0339 0.0530 0.0819 The deficiency in the observed proportions of heterozygotes observed for the MN system may be attributed either to inbreeding or to the fact that o w sample included individuals born in different Atacameiio villages. The heterogeneity caused by the inclusion in one sample of different subpopulations may result in heterozygote deficiency (Cavalli-Sforza and Bodmer, 1971). Phenotype and gene frequencies of the A and B histocompatibility loci are in reasonably good agreement with the results of Van der Does et al. (1972) obtained in the Ataca- 245 meiio village of Socaire. The A2, Aw19, and A9 (Aw24) genes of the A locus exhibit the highest frequencies following a general tendency reported for South American Indians (Black et al., 1980). When considering the B locus, the B15 and B40 genes turn out to be the most frequent. The high CW1 frequency is somewhat unusual and, if verified, may be attributed to post-Columbian admixture and or drift. In the absence of family data, haplotype frequencies and linkage disequilibrium parameters (D values) were computed from three-locus phenotypes using the method suggested by Piazza (1976). The three most frequently encountered haplotypes among the Atacameiios are Aw19, B15, CW1, A2, B E , C-, and A2, BW35, CW4. These haplotypes exhibit frequencies of 0.2450, 0.1569, and 0.1282, respectively. Other less frequently observed haplotypes were A2, B15, CW1 (0.07), Aw19, B40, CW1 (0.061, A9, BW35, CW4 (0.05),and finally A2, B15, CW4 (0.04). The three most frequent haplotypes exhibited positive D values above 0.03. Given the small sample of probably related individuals (an unavoidable feature of isolated Indian populations), we were reluctant to test the significance of the D values. Nevertheless, we note that the combination A2, BW35, C4 accounted for 14% of all sequences among South American Indians (Black et al., 1980). The presence among the Atacameiios of the A, B, r, and HLA-A1 genes in relatively high frequencies may indicate Caucasian admixture. The statistical procedures suggested to estimate the amount of “foreign” genes in a population start from the supposition that the gene frequencies of the ancestral populations are known (see, for example, Bernstein, 1931; Roberts and Hiorns, 1962; Chakraborty, 1975; Szathmary and Reed, 1978).Only rarely, however, can these fundamental parameters be directly estimated. The Atacameiios are one of these few exceptions. Actually, Allison et al. (1978) published the results of ABO blood group typing of 49 Atacameiio mummies dated by radiocarbon a t 200-300 AD and of 12 mummies belonging to the colonial period. Under the assumption that technical problems have not biased the results of Allison et al. (19781, that the frequency of 0 in the Spanish populations is 0.6487 (Campillo, 1976), and that this frequency has remained relatively constant over the last 450 years, it is possible to estimate the Caucasian admixture of the Atacameiios of Toconao (Table 5). The M values and error 246 F. ROTHHAMMER ET AL. variances were obtained following Bernstein (1931) and Cavalli-Sforza and Bodmer (1971). The increase of Caucasian admixture in the Atacameiios of Toconao after the Spanish conquest is a n expected finding. It is surprising, however, that despite the fact that this aboriginal population is undergoing transculturation a t a n increasing rate, Caucasian admixture has remained constant during the last 20 years. ACKNOWLEDGMENTS This work was supported by the Deutsche Forschungs-gemeinschaft, Bonn-Bad Godesberg, Project 1068 of the Fondo Nacional de Ciencias, CONICYT, Santiago de Chile, Project B-518-845F of DIB, the University of Chile, and grant 820599LJNDPMrorld BanW WHO Special Programme for Research and Training in Tropical Diseases. We are grateful to the members of our field team, Mrs. Heide Benkmann, Mrs. Petra Bogdanski, Mrs. Patricia Carvajal, Mrs. Syl-. via Quevedo, and Dr. Hernan Palomino. We are also indebted to the Alcalde of San Pedro, Mr. Hans Schmauck Alarcon, and to the director of the Archaeological Museum of San Pedro, Mr. Agustin Llagosteras, for their help in solving logistic problems. We are especially beholden to Mrs. Amanda Fabian Gonzales for helping us to organize the examinations in Toconao. LITERATURE CITED Allison, JA, Hossaini, AA, Munizaga, J, and Fung, R (1978) ABO blood groups in Chilean and Peruvian mummies. Am. J. Phys. Anthropol. 49:139-142. 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