Blood group serum protein and red cell enzyme groups of Amerindian populations in Colombia.код для вставкиСкачать
Blood Group, Serum Protein and Red Cell Enzyme Groups of Amerindian Populations in Colombia R. L. KIRK,' E. M. McDERMID,' N. M. BLAKE,' D. C. GAJDUSEK,2 W. C. LEYSHON AND R. MAcLENNAN 1 Department of H u m a n Biology, T h e J o h n Curtin School of Medical Research, Canberra, Australia; National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland; 3 H u m a n Genetics Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland; 4 International Center for Medical Research and Training, T u l a n e University-Universidad del Valle, Cali, Colombia. KEY WORDS South American Indians. Colombia. Blood groups. Serum proteins . Cell enzymes. ABSTRACT Red cell samples from persons belonging to four Amerindian linguistic groups in Colombia were investigated for genetic variants in eight blood group systems: for three of the groups investigations were extended to ten red cell enzyme and four serum protein systems. The groups studied are the Noanama (including six Empera) of the Rio Siquirisua and Rio Docampado on the Pacific lowlands and the Cofan, Ingano and Siona Indians of the Upper Rio Putumayo and its tributaries to the east of the Andes. Only blood group 0 was present among two of the groups and the same groups were 100% Kp(b +), k in the Kell system. Di(a+) frequencies were high in three groups and there was marked variation between groups for the MNS, Rh, P, Lewis and Duffy systems. Polymorphism in all the three linguistic groups studied for serum proteins and red cell enzymes was present only in the red cell acid phosphatase, phosphoglucomutase (locus-1) and haptoglobin systems. 6-phosphogluconate dehydrogenase was polymorphic in the Noanama, and caeruloplasmin was polymorphic in the Ingano linguistic group. In addition two persons belonging to the Cofan linguistic group revealed the presence of an "atypical" component in the lactate dehydrogenase system. No variation was found in the other six red cell enzyme and two serum protein systems. Comparison with published data on red cell enzyme and serum protein groups for other South American Amerindian populations shows the Colombian populations studied here most closely resemble the Cayapo of Brazil. Approximately 6 % of the 175 million persons in South America are recognized as Amerindian, and of these i t has been estimated that about one-tenth are unacculturated at the present time (Salzano, '68). These are distributed among a large number of endogamous groups or tribes differentiated frequently by geographical location and socio-cultural patterns of which distinctive language or dialect is often the most striking. During the last decade increasing attention has been given to the genetic structure of such groups, and a number of them particularly in Brazil, Peru and Venezuela have been studied in some detail (Arends et al., '67; Arends et al., '70; Fitch and Neel, AM. J. PHYS.ANTHROP.,41: 301-316 '69; Johnston et al., '69; Neel et al., '64; Neel and Ward, '70; Salzano, '71, '72; Salzano et al., '72a; Salzano et al., '72b; Shreffler and Steinberg, '67; Tashian et al., '67; Weitkamp and Neel, '70). In addition to these investigations a large number of studies of the distribution of red cell antigens and a smaller number of some of the serum protein groups were summarized up to November 1967 by Post et al. ('68) and more recent investigations together with new data on the red cell enzyme and serum protein groups of the Cayapo of Brazil are included in Salzano et al. ('72b). Relatively few of the population genetic studies carried out previously have involved groups living in Colombia, a n d with 301 302 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON AND MAcLENNAN the exception of one study of the Ica and Paez which included investigation of transferrins (Arends and Gallango, '65) all were concerned with red cell antigens, mainly the ABO blood groups. Only two populations, the Ica and Tunebo, have been tested for a range of red cell antigen systems, ABO, MNS, Rh, Jk, Fy, Di, P and Lewis (Layrisse et al., '63). Because of the relative paucity of data on red cell enzyme and serum protein groups among Amerindian populations in South America and particularly the absence of any kind of such information for Colombian Amerindian populations we considered it fortunate that we had the opportunity to visit Colombia and collect samples from persons representing several linguistic groups. peans. Rare marriages with the Empera do occur (Gajdusek, '72). Intensive anthropological work on the Siguirisua was conducted in '64-'65 by Elizabeth Kennedy ('72). The geography of the area has been described by West ('57) and Eder ('63). Approximately 50% of the Siguirisua River population are included in this study. The Empera live mainly to the north on the other river systems, although a small enclave was found on small tributaries of the Rio Docampado (fig. 2). There are over five times as many Empera as Noanama speakers. We studied six individuals from one household of Empera on the Quebrada Basura, a small tributary of the Docampado river below the Rio Siguirisua. ETHNOGRAPHIC BACKGROUND The Putumayo Indians The Putumayo Indians live on the flat forested lowlands of the Rio Putumayo. The small Indian population is in close contact with and is greatly outnumbered by colonizing Mestizos. Mestizo and Black settlers live in scattered homesteads along the rivers between the Indian enclaves. There is very little social contact or intermarriage between the Indians and these settlers. The Indian enclaves we studied, shown on the map in figure 3 , belong to three groups: Cofan, Ingano and Siona (Igualada and Castellvi, '40). We were told of a small settlement of recently immigrant Chocoan Indians on the Rio Acae (Gajdusek, '72). There are no other known contacts between the Choco and the Putumayo groups. The three Putumayo groups studied marry infrequently with each other. The offspring of marriages with mestizos tend to move out of the Indian community. The Cofan live along the San Miguel, Aguarico and Guamues rivers. Their population of some 550 people extends into Ecuador. The Cofan language has not been found to have a n y definite relation to any other linguistic family of American Indian languages (Robinson, '70). Although dialects vary on the above rivers, the culture is the same. Only the Cofan living along the Rio San Miguel and its tributaries are included in this study. The Ingano speaking the Quechua language of the Ingas (Incas) are scattered over a wide area of the lowlands (Ortiz, The Indians we have studied are from two lowland areas of Colombia, the Pacific and the Putumayo. Their geographic locations are indicated in the maps 'in figures 1 to 3. Nearly all Indians in the Pacific lowlands are Chocoans, estimated by Holmer ('63) to total 10,000. They speak Carib languages that can be divided into two distinct groups: the Empera or Northern Choco and the Noanama, also called the Southern Choco or Waunana (Stout, '48; Wassen, '63). The Putumayo groups are separated from the Chocoans by the whole Andean cordilleras. There are no linguistic or ethnological data suggesting relationships between the Indians of the two regions. The Pacific Indians The Noanama whom we studied live along the Siguirisua River. They are relatively isolated and unacculturated and their population of 300 is approximately 14% of the total Noanama (Reichel-Dolmatoff, '60; '62). They live in about 20 large households scattered along the length of the Rio Siguirisua, a large tributary of the Docampado river (fig. 2). Blacks of African origin inhabit the lower reaches of the Rio Docampado and the Rio Siguirisua; although they are close neighbors with the Noanama there is little social contact between them. There was no evidence of any intermarriage between the Noanama and these Blacks or with Euro- SERO-GENETIC STUDIES IN COLOMBIA 303 Pacific Ocean Bogota Buenaventura *Call km - 0 50 100 150 t I - ( - Putumavo Indians z ECUADOR Fig. 1 Geographic location of the two study areas in Colombia. -7 304 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON AND MAcLENNAN ...... ..':... ::.::::'.,:: .............,...,... .'...:.;f(:;.'. ...._.. ... ....... ..................... . .. .... km 0 Fig. 2 Distribution of the Empera and Noanama linguistic groups of Chocoan Indians on the Pacific side of the Andean cordilleras (adapted from Reichel-Dolmatoff, '60). 305 SERO-GENETIC STUDIES IN COLOMBIA 0 2 0, 9 0 2 0, 9 M a ; 1 0 F 3 306 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON A N D MAcLENNAN '65). These Quechua speaking peoples have reputedly descended from the Andean Altiplano of Colombia or Ecuador, where some groups, such as one in the Sibundoy valley of Colombia, still speak Quechua. However, the relation between present day highland and lowland Quechua speakers is not clear. We studied one large group of Ingano speakers, who reside at San Marcelino on the San Miguel river. The Siona live along the Putumayo river (fig. 2). They have been fragmented since 1932 (Chaves, '45) and their present sittuation is one of cultural disintegration (de Recasens, '64-'65). Their language is in the Western Tukano family (Ortiz, '65) whose speakers are scattered in Colombia and Ecuador. There are perhaps 300 Siona of whom some 200 live on both sides of the Putumayo at Buena Vista. with a range of antisera belonging to eight red cell antigen systems. In the case of the Siona a few of the samples were found to be unsuitable for typing and the totals have been adjusted appropriately. Further, because of the small number of Empera (a total of six from one family group) they have been included in all the tabulations with the Noanama. Separate evaluation of these six individuals revealed no unusual phenotypes in any of the systems studied. ABO South American Amerindian populations are characterized by extremely high frequencies of blood group 0, achieving 100% in many cases. The present study, as shown in table 1, is no exception, only eight of 361 persons tested being other than group 0. These eight individuals comprised three group A1 persons among the Ingano, and MET H 0D S three group A1 and two group B persons Blood samples were taken by venepunc- among the Siona. Similar low frequencies ture into "Bayer" venules and carried for for the A and B blood groups have been reperiods ranging from a few hours to a few ported for a number of other Amerindian days at a temperature of 4 " to 10" C until -groups in Colombia and the data have been placed on wet ice for transport to Washing- summarized by Post et al. ('68), and Salton, D.C. Here serum was separated and zano et a1 ('72a). a portion of the clots and serum frozen at MNSs - 70" C. The frozen samples, except for Tests were performed with anti-M, -N, those from the Siona, were transported at dry-ice temperature to Canberra where -S and -s as well as with anti-U. All samthey were stored in a liquid nitrogen re- ples were U( t). Table 2 demonstrates frigerator until ready for testing for red cell marked differences between all four linguistic groups in the frequencies of the enzymes and serum proteins. Blood grouping was carried out in Wash- genes, but in three of the groups the most ington on cells recovered from the un- frequent is M s ; only in the Cofan is it exceeded by M S . The Noanama are strikingly frozen clot. Electrophoretic conditions, buffers and different from the other three groups, with substrate procedures for the enzyme and an N s frequency of 28.4% more than twice serum protein tests were identical with that of the Cofan, and more than four those described previously (Malcolm et al., times that of the Ingano: the Noanama frequencies are similar to those for the '72). Gene frequencies were estimated using Cayapo in Brazil reported by Salzano et al. the maximum likelihood program written ('72a). The tabulation of Post et al. ('68) for us by W. J. Schull. Though the series and Salzano et al. ('72a) shows wide Auccontained persons of varying degrees of tuations in the gene frequencies of the relationship all individuals were given MNSs system in other South American equal weight in the gene frequency calcu- Amerindian populations, but only Layrisse lations, and tests for Hardy-Weinberg equi- et al. ('63) have reported values for this system in Colombia. Their results are withlibrium assumed random mating. in the ranges found for the groups studied RESULTS here. Rhesus Blood groups The five Rh antisera -C, -D, -E, -e and A total of 168 Noanama, 78 Cofan, 51 Ingano and 64 Siona Indians were tested -c were employed as well as -Cw . No sam- 307 SERO-GENETIC STUDIES IN COLOMBIA TABLE 1 Phenotype distribution for eight red cell antigen systems among some Amerindian populations in Colombia Noanama Ingano Cofan Siona Group - No. Percent No. Percent ABO A B No. Percent No. Percent 3 5.88 4.69 3.12 92.19 0 168 100.00 78 100.00 48 94.12 3 2 59 Tot a1 168 100.00 78 100.00 51 100.00 64 100.01 6 26 53 2 13 49 3.57 15.48 31.55 1.19 7.74 29.17 14 36 10 17.95 46.15 12.82 4 19 19 2 7.84 37.25 37.25 3.92 10 4 12.82 5.13 1.19 10.12 2 2 2.56 2.56 3.92 3.92 3.92 1.96 6.67 36.67 31.67 1.67 10.00 13.33 2 17 2 2 2 1 4 22 19 1 6 8 168 100.01 78 99.99 51 99.98 60 1 0.60 91 66 4 6 54.17 39.29 2.38 3.57 2 38 31 1 6 2.56 48.72 39.74 1.28 7.69 29 20 56.86 39.22 4 36 18 5 6.35 57.14 28.57 7.94 2 3.92 168 100.01 78 99.99 51 100.00 63 100.00 114 54 67.86 32.14 69 9 88.46 11.54 46 5 90.20 9.80 42 18 70.00 30.00 168 100.00 78 100.00 51 100.00 60 100.00 Lewis Le(a ) Le(a - ) 34 134 20.24 79.76 1 77 1.28 98.72 1 50 1.96 98.04 2 58 3.33 96.67 Tot a1 168 100.00 78 100.00 51 100.00 60 100.00 Duffy Fy(a ) Fyfa - ) 56 12 92.86 7.14 60 18 76.92 23.08 44 7 86.27 13.73 57 3 95.00 5.00 Total 68 100.00 78 100.00 51 100.00 60 100.00 68 100.00 78 100.00 45 6 88.24 11.76 55 91.67 5 8.33 MNSs MS MSs Ms MNS MNSs MNs NS NSs Ns Tota1 Rhesus R z R z (CCDEE) RzR, (CCDEe) RIRl (CCDee) R1R2(CcDEe) Rlr (CcDee) RzR2(ccDee) Total 100. P p1+ p1Total + + Kell Kp(b + ), k Kp(a + ) KpCb Kp(a ) Kp(b + + ), Kk + ), k Tot a1 168 100.00 78 100.00 51 100.00 60 100.00 Diego Di(a + ) Di(a - 168 100.00 28 50 35.90 64.10 16 35 31.37 68.63 36 25 59.02 40.98 Total 168 100.00 78 100.00 51 100.00 61 100.00 308 KIRK, McDERMID, BLAKE, GAJDUSEK. LEYSHON AND MAcLENNAN TABLE 2 G e n e f r e q u e n c i e s f o r red cell a n t i g e n s y s t e m s listed in table 1 Gene ABO A B 0 Noanama Cofan Ingano Siona ,0299 1.oooo 1.oooo ,9701 .0237 ,0158 ,9605 MNSs MS Ms NS Ns ,1499 .5465 ,0197 .2838 .4661 ,3929 ,0211 ,1199 .2843 .5 784 .0784 .0588 ,2917 ,5833 ,0250 ,1000 Rhesus R,(CDE) R,(CDe) Rz(cDE) R 0 (cDe) ,7550 ,2337 ,0113 ,0129 ,7050 .2756 ,0065 ,7647 ,2353 .0335 .7839 .1411 ,0415 P' ,4331 ,6603 .6869 .4523 Lewis Lea ,2024 ,0128 .0196 .0333 Duffy FYa .7327 .5196 .6295 ,7764 1.oooo 1.oooo 1.oooo 1.oooo ,9412 ,9412 1 .oooo KPh Diego Di a 0.0000 gene frequencies are higher than those reported by Layrisse et al. ('63) in Colombia but close to the values given for other South American groups by Post et al. ('68), and for the Cayapo in Brazil by Salzano et al. ('72a). Lewis Tests with anti-Lea revealed a major difference between the Noanama and the other three linguistic groups. Twenty percent of the former were Le(a +) compared with only 1 to 3% in the other groups. With few exceptions, such as the Xavante of Brazil (Gershowitz et al., '67) most populations of Indians in South America are almost entirely Le(a-). Salzano et al. ('72a) report nearly 8 % of the Brazilian Cayapo to be Le(a +). P Kell k DUffY The Fy(a ) frequencies ranged from 76.9% for the Cofan to 95.0% for the Siona. Similar ranges in frequency are found for other Amerindian populations: Post et al. ('68), and Layrisse et al. ('63) give almost identical values in Colombia. Salzano et al. ('72a) found 92% of the Cayapo in Brazil to be Fy(a ). + ,9583 + Kell Tests with four antisera -K, -k, -Kpa and -Kpb revealed that nearly all persons were ple reacted positively with the latter: in Kp(b + )k, the commonest phenotypic comaddition no cdelcde (rr) persons were de- bination in all parts of the world. However tected and the gene frequencies were cal- five of the 60 Siona were Kp(a ) Kp(b )k culated assuming absence of the r gene. and six of 51 Ingano were also K. This latAmong all four groups the RIRl and ter combination (Kp(a +)Kp(b +)Kk is unR I % phenotypes accounted for 85% or usual since the Kk, Kp(a)Kp(b) gene pairs more of the total. The R 1 gene frequency appear to be inherited independently. The fell within the range 0.71 to 0.78, with occurrence of six Kp(a ) persons as also R2 in the range 0.14 to 0.28. R" is absent K in the Ingano can be explained only as among the Noanama and Ingano, and only the result of the Kp" and K genes occurachieves a frequency of 0.01 in the Cofan, ring in the Cis conflguration in a group of and 0.03 in the Siona. Like the MNSs sys- closely related individuals. tem the rhesus system is characterized by Diego wide variations in frequency among Amerindian populations. Even in Colombia the The Diego blood group system was first populations studied by Layrisse et al. ('63) discovered among Amerindians in South were more widely divergent than those re- America (Layrisse et al., '55) and it was ported here. proved to be an interesting marker system among Amerindian populations, as well as P among Mongoloid populations in other Tests with anti-PI revealed positive reac- parts of the world. In the present instance tions ranging from 68% among the Noa- all persons were tested with Anti-Dia and nama to 90% among the Ingano. The Pya some with the antithetical antibody -Dib. ,1994 ,1716 ,3598 + + + SERO-GENETIC STUDIES IN COLOMBIA Of those tested all were found to be Di (b +). The frequency of Di(a +) persons however was 0 % among the Noanama, 31 and 36% among the Ingano and Cofan respectively and 59% among the Siona. Similar ranges have been found in other studies summarized by Post et al. (‘68). Salzano et al. (’72a) report frequencies close to 40% for Di(a ) persons in various Cayapo groups in Brazil. + Serum protein and red cell enzyme groups The phenotype distributions for ten red cell enzyme and four serum protein groups among the Noanama, Cofan and Ingano Indians are given in table 3. Some serum samples were deficient in quantity so that the total number of serum protein group determinations was less than that for the red cell enzymes groups. In addition one red cell sample was exhausted before the checking of PGM groups was completed. Because of the conditions under which the samples were collected and the elapsed time before arrival in Canberra no attempt was made to type for glucose-6-phosphate dehydrogenase deficiency. All other systems, however, gave reproducible results and we consider the likelihood of errors in typing to be negligible. Gene frequencies for those systems revealing variation, except for LDH which will be discussed in more detail below, are given in table 4. X’ values calculated on the assumption of Hardy-Weinberg equilibrium revealed no significant departure from expectation in any system. Only four of the ten red cell enzyme systems examined revealed phenotypic variation in the three populations studied, and of these only two were polymorphic by the usual definition of having a variant gene frequency of 0.01 or higher. In the red cell acid phosphatase system three phenotypes, A, AB and B were detected, and the P“ gene frequency did not differ significantly among the three populations, having a mean value of 0.22. This is comparable with the value given by Salzano et al. (‘72b) for the Cayapo (0.21) and by Tashian et al. (’67) for the Xavante in Brazil (0.19) but very much higher than the 0.02 among the Yanomama (Arends et al., ’67) or the 0.05 for the Makiritare in Venezuela (Weitkamp and Neel, ’70). 309 For locus-1 of the phosphoglucomutase system three phenotypes 1-1, 2-1 and 2-2 were present and the P G M ’ , gene frequency of 0.78 again was almost identical with that for the Cayapo in Brazil (0.76) given by Salzano et al. (‘72b). Much higher values (0.94 and 0.85) were found respectively for the Yanomama and Makiritare in the papers cited above, although in the present study the value of 0.84 for the Cofan is not appreciably different than the value for the Makiritare in Venezuela. In the 6 - phosphogluconate dehydrogenase system electrophoretic variants were detected only among persons belonging to the Noanama linguistic group, four of 170 individuals having the “common variant” heterozygote phenotype (Carter et al., ’68). The low frequency of the PGDC (listed as PGDB by American authors) appears to be a characteristic of Amerindians in South America. Salzano et al. (‘72b) found no variants and Weitkamp and Neel (‘70) found five heterozygotes in one Makiritare village but none in a further six villages and Tashian et al. (’67) found no GPGD variants among 185 Xavante in Brazil. We have not observed a n y significant diminution of GPGD activity comparable to that postulated for “PGD-Makiritare” by Weitkamp and Neel (‘70). The only other red cell enzyme system which revealed any variation was lactate dehydrogenase. All 294 samples tested have been listed in table 3 as normal. Two samples among the Ingano linguistic group, however, showed the “atypical” pattern which is illustrated in figure 4. In both samples a strong single band occurs anodally to isozyme 3, and it appears to be specific for lactate as substrate. Although in the approximate position of LDH-X found in mature male gonadal tissue and sperm, comparison with human sperm preparations showed that the x-band and the “atypical” component were not of identical mobility. One of the propositi was a female aged 16 years and the other a 15 month old male. In the absence of full family data for the propositi the interpretation of the “atypical” LDH patterns remains obscure. All the other red cell enzyme systems, PGM-locus 2, adenylate kinase, malate dehydrogenase, peptidase A, peptidase B and indophenol “oxidase” revealed no elec- 310 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON AND MAcLENNAN TABLE 3 P h e n o t y p e distribution for red cell e n z y m e u n d s e r u m p r o t e i n groups trmoizg some A m e r i n d i m g r o u p s i t 2 Colombia Noanama Cofan A l l groups Ingano System No. Percent No. Percent No. 9 58 102 5.33 34.32 60 36 2 32 40 2.70 43.24 54.05 Total 169 100.01 74 99.99 6-Phosphogluconate dehydrogenase 6PGD A AC Total 166 4 170 97.65 2.35 100.00 74 100.00 - - - 74 100.00 50 100.00 Phosphoglucomutase (locus 1) P G M , 1-1 2-1 2-2 96 68 5 56.80 40.24 2.96 51 22 1 68.92 29.73 1.35 25 20 5 Total 169 100.00 74 100.00 Phosphoglucomutase (locus 2) PGMz 1-1 169 100.00 74 Lactate dehydrogenase LDH Normal 170 100.00 74 Malate dehydrogenase MDH Normal 170 100.00 Adenylate kinase AK 1-1 170 Peptidase A P e p A 1-1 1-1 weak Total Acid phosphatase AcPh A AB B Percent No. - - 14 36 28.00 72.00 11 104 178 3.75 35.49 60.75 50 100.00 293 99.99 50 100.00 290 4 294 98.64 1.36 100.00 50.00 40.00 10.00 172 110 11 58.70 37.54 3.75 50 100.00 293 99.99 100.00 50 100.00 293 100.00 100.00 50 100.00 294 100.00 74 100.00 50 100.00 2 94 100.00 100.00 74 100.00 50 100.00 294 100.00 126 44 74.12 25.88 52 22 70.27 29.73 37 13 74.00 26.00 215 79 73.13 26.87 I - Percent 170 100.00 74 100.00 50 00.00 294 100.00 Peptidase B P e p B 1-1 170 100.00 74 100.00 50 00.00 294 100.00 Indophenol oxidase Oxidase Normal 170 100.00 74 100.00 50 00.00 294 100.00 155 100.00 68 100.00 38 3 92.68 7.32 26 1 3 98.86 1.14 C aeruloplasmin CP B A B - - - - 155 100.00 68 100.00 41 100.00 264 100.00 Hap toglobin Hp 1-1 2-1 2-2 “0” Total 27 79 48 1 155 17.42 50.97 30.97 0.65 100.01 42 21 5 61.76 30.88 7.35 - - 68 99.99 22 8 6 5 41 53.66 19.51 14.63 12.20 100.00 91 108 59 6 264 34.47 40.91 22.35 2.27 100.00 Transferrin Tf C 155 100.00 68 100.00 41 100.00 264 100.00 Albumin 155 100.00 68 100.00 41 100.00 264 100.00 Total I Two of the samples gave “atypical” LDH patterns. These are discussed in the text. SERO-GENETIC STUDIES IN COLOMBIA TABLE 4 Gene frequencies f o r red cell e n z y m e and serum protein systems showing varintion i n table 1 Alleles All groups Noanama Cofan Ingano 0.225 0.775 0.243 0.757 0.140 0.860 0.215 0.785 0.988 0.012 1.000 1.000 - - 0.993 0.007 PGM (locus 1) PGM,' PGM12 0.769 0.231 0.838 0.162 0.700 0.300 0.775 0.225 CP C P 1.000 1.000 - 0.963 0.037 0.994 0.006 0.432 0.568 0.772 0.228 0.722 0.278 0.562 0.438 Ac.Ph. Pa Pb 6PGD PGD A PGDC CPA HP HP' H p' - trophoretic variants. Peptidase A showed variation in intensity of the normal 1-1 band, some being classified subjectively as weak. We have noted such variation repeatedly for samples collected under field conditions, and although there may be a genetic basis for part of the variation we believe that much is due to instability of the peptidase A itself. Four serum protein systems, haptoglobin, transferrin, caeruloplasmin and albumin were examined: only haptoglobin was polymorphic in the total population. The H p ' gene frequency of 0.43 for the Noanama was significantly lower than for the Cofan and Ingano linguistic groups (0.77 and 0.72 respectively). The overall Hp' gene frequency of 0.56 is again almost identical with the Cayapo frequency of 0.58 given by Salzano et al. ('72). The latter authors summarize the H p l gene frequencies for 73 series of Amerindians in South America, giving a range of values from 0.21 to 0.89, with all but two values (Yupa and Guayakis) falling in the range 0.34-0.89. For transferrin the situation is more complex. Nearly half the series of Amerindian populations studied in South America reveal the presence of genetic variants other than Tf C. Some of these variants are claimed to be Tf D1 similar to that present in black American populations, others are designated Tf Dchi, which 311 is widely distributed in Mongoloid populations in other parts of the world. Kirk ('68) has pointed out, however, that in many cases no critical discrimination of the transferrin variant found in a particular population sample has been made so that comparisons between Amerindian groups on the basis of type of transferrin variant present must be treated with caution. In the present study only Tf C was detected. Among South American Amerindians genetic variation at the caeruloplasmin locus has been investigated by Arends et al. ('67, '70) and Salzano et al. ('72b). No variants were reported for the Yanomama and Makiritare in Venezuela, but Salzano and his colleagues found 9 % BA heterozygotes among the Cayapo in Brazil. In our own study we have found three persons, a mother and two of her children, among the Ingano linguistic group who were BA heterozygotes. Careful comparison of these phenotypes using the slab acrylamide technique of McCombs et al., ('70) as well as using the standard starch gel technique could not differentiate the A band from that of a BA control (kindly supplied by Dr. D. G. Shreffler). It is possible that our own variant is identical with that found among the Cayapo. The other system, serum albumin, revealed no phenotypic variation. Albumin variants have been found in three of the four South American Amerindian series investigated previously, only the Cayapo of Brazil having no variants. Superficially this suggests another similarity between the present series and the Cayapo. However, the Albumin variant found among the Warrau by Arends et al. ('69) and among the Makiritare by Arends et al. ('70) is claimed by the latter authors not to be detectable after starch-gel electrophoresis in the standard buffer systems used for detecting albumin variants (Weitkamp et al., '69). Since we have not employed the buffer system used by Arends and his group we cannot exclude the possibility that variants similar to Albumin-Warrau or Albumin-Makiritare are present in the linguistic groups studied in the present investigation. DISCUSSION The detailed blood group, serum protein and enzyme group studies reported here 312 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON AND MAcLENNAN LDH 1 LDH 2 + t LDH 3 c. LDH 4 Origin a. b. c. d. Fig. 4 “Atypical” LDH patterns from two persons belonging to the Ingano linguistic group (b and c) compared with normal controls (a and d). for Amerindian populations in Colombia are of interest from several points of view. Firstly, they may be used to indicate the degree of genetic similarity between the populations sampled in the two broad regions studied, the Noanama (including the very small sample of Empera) from the Pacific lowlands, and the three groups from the Putumayo, each of which in turn is relatively isolated from the others. Secondly, the results may be used to compare the Colombian populations with those in other parts of South America for which comparable data is available. Finally, studies of this kind are of value for the information they contribute on the amount of genetic heterogeneity present in small human populations, including the occur- SERO-GENETIC STUDIES I N COLOMBIA rence of specfic mutants with localized distributions. With respect to the first of these points, our data indicates the distinctiveness of the Chocoan-speaking Noanama from the Putumayo groups, and this is demonstrated in a number of systems. For example, the Noanama have only 15% M S but 28% N s in the MNSs system in contrast to the range of M S from 28 to 47% and N s from 6 to 12% for the Putumayo groups. Similarly the Lc" frequency for the Putumayo groups has a range from 1 to 3 % , but is 20% in the Noanama and the latter have only 43% for the Hpl gene whilst the two Putumayo groups studied have 72 and 7 7 % . The Noanamo also do not have the Di" gene, whereas the Di" frequency among the Putumayo groups is 17 to 36 % . There are some marked differences between the Putumayo groups themselves. This is not surprising perhaps, since the three groups studied for the red cell antigen systems (two of which were investigated also for the cell enzyme and serum protein systems) provide little evidence for intermarriage between them and belong to distinctive linguistic families. However, there is no consistent pattern for the differences between the three Putumayo groups so that on the basis of the present evidence we cannot pick out the Quechuaspeaking Ingano for instance a s being quite different from the Cofan and Siona. Also, since data is not available for Quechuaspeakers from the Colombian Altiplano we can add nothing of value toward solving the problem of the relationship between the highland and lowland Quechua speakers One further point of interest is the possible influence of non-Amerindian populations on the gene pool of the Putumayo groups. As emphasized in the section on the ethnography of these groups they are surrounded by numerically superior Mestizo and Black populations. With the exception of the ABO and possibly the Rhesus blood group systems the evidence indicates little if any introduction of alien genes into either the Pacific or Putumayan populations studied here. In the ABO system the Ingano have 3% of A genes whilst the Siona have nearly 4% of A and B genes combined. The Noanama and Cofan have only 0 genes, a situation considered to be characteristic of Amerindian populations 313 in South America in the pre-contact period. In the Rhesus system the R gene complex present in the Cofan and Siona groups may be also introduced from alien sources. By contrast, a number of genes characteristic of European or Black African populations were not detected in any of the Pacific or Putumayan groups. These genes include the r(cde) gene of the Rhesus system, U negative in the MNS system, P C and PR in the red cell acid phosphatase system, variants at the PGM second locus and slow-moving DI variants in the transferrin system. The absence of such specific variants does not rule out the possibility of intermarriage between the Amerindians and their alien neighbours, but suggests either that such intermarriage is infrequent or that the hybrid offspring are not identified with the parent Amerindian group. The ethnographic evidence supports the latter suggestion, at least for some of the Putumayo groups. If we turn now to an examination of the genetic relationship between the Colombian groups studied here and Amerindian populations in other parts of South America we are faced by the paucity of information for a wide range of genetic markers in order to make a detailed comparison possible. The high frequency of the blood group 0 gene in the ABO system and the very variable frequencies between the different linguistic groups for many of the genes in some of the other blood group systems such as Ns, R. and Di" are comparable to the situation reported for Amerindians in other parts of South America. What is of interest is that for the serum protein and red cell enzyme systems which are polymorphic the frequencies of the genes are very similar to those reported for the Cayapo in Brazil, but different in several respects from the results found by other investigators for Xavante in Brazil or the Yanomama and Makiritare in Venezuela as noted in the preceding section. The blood group results also are similar in a number of respects to these reported for the Cayapo of Brazil. When more information is available the significance of these relationships may become clearer: we intend to publish a more detailed analysis in the future. Finally we wish to note some points of interest about the results of our present 314 KIRK, McDERMID, BLAKE, GAJDUSEK, LEYSHON AND MAcLENNAN analysis with respect to the genetic heterogeneity of small human populations, and the occurrence of mutations with restricted local distribution. The genetic heterogeneity for the systems studied here is low in contrast to that reported for European and Black African populations (Harris and Hopkinson, ’72). This is true for the ABO, Rhesus and Kell blood group systems, and for the serum protein and red cell enzyme systems. Only two of the ten red cell enzyme systems and one of the four serum protein systems are polymorphic by usual standards in all the three linguistic groups for which information is available, though a n additional red cell enzyme system is polymorphic among the Noanama and an additional serum protein system is polymorphic among the Ingano. This lack of heterogeneity is characteristic of peripheral non-human populations and unpublished information from one of our laboratories indicates that this is true also for peripheral human populations. The Pacific and Putumayo groups therefore may be considered as small genetic isolates with increased genetic homogeneity, a condition which may be further increased if their culture does not permit the retention of genetic variability introduced from sources outside the group. In this connection it is interesting that we detected no new mutants in a n y of the systems investigated, with the exception of the two persons with an “atypical” component in the lactate dehydrogenase system. This unusual LDH variant merits more detailed comment. Comparison with the LDH-X present in sperm from Caucasian controls showed the “atypical” component to have a slightly different mobility, but it would be of interest to compare directly with the LDHX present in extracts of sperm from males belonging to the Cofan linguistic group. It seems unlikely, however, that the LDH-X of Amerindians in Colombia would be different in its electrophoretic behaviour from that present in Caucasians. Moreover, if the “atypical” band and the Cofan LDH-X were identical it would be necessary to postulate that the gonadal isozyme was derepressed in the red cells of the two persons encountered in the present study. It is more tempting to postulate that the “atypical” component in these two persons is related to some disease process, but further study is needed to establish if this is correct. It is relevant to note that in nearly 10,000 red cell samples examined for electrophoretic variants in one of our laboratories during the last few years only one analogous “atypical” pattern has been detected. This was found in a n apparently healthy Chinese in Singapore, where a single “atypical” component was present in the LDH pattern migrating slightly slower than isozyme 2 (Blake et al., ’73). ACKNOWLEDGMENTS We are indebted to Mrs. Elizabeth Robertson, Mrs. Kathy Sims and Mr. Robert Taylor for excellent clerical and technical assistance during the conduct of this research. We also thank Dr. Nicholas Escobar, Director of the Texaco Company in Colombia, and his staff at Orito for helicopter transport and other logistics support which he made available to us in the Putumayo region. We are grateful to Sr. Ugo Cuevas of Cali, Colombia for sea transport from Buenaventura to Belem on the Rio Docampado and the return voyage in one of his shrimping vessels. LITERATURE CITED Arends, T., and M. L. Gallango 1965 Transferrin groups in South American Indians. Bibl. Haemat., 2 3 : 4 0 5 4 1 1 . Arends. T., G. Brewer, N. Chagnon, M. L. Gallango, H. Gershowitz, M. Layrisse, J. Neel. D. Shreffler, R. Tashian and L. Weitkamp 1967 Intratribal genetic differentiation among the Yanomama Indians of southern Venezuela. Proc. Nat. Acad. Sci. (U.S.A.), 57: 1252-1259. Arends, T., M. L. Gallango, M. Layrisse, J. Wilbert and H. D. Heinen 1969 Albumin Warao: New type of human alloalbuminemia. Blood, 33: 414420. Arends, T., L. R. Weitkamp, M. L. Gallango, J. V . Neel and J. 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