Of the Chamorros of Guam CHRIS C

Blood Group and Haptoglobin Frequencies of the Chamorros of Guam CHRIS C. PLATO' AND MANUEL CRUZ2

National Institute of Neurological Diseases and Blindness, National Institutes of Health, Bethesda, Maryland 20014. 2 National Institute of Neurological Diseases and Blindness Research Center, Guam Memorial Hospital, Agana, Guam. THE ISLAND of Guam recently has been the center for the investigation of two rare neurological diseases, amyotrophic lateral sclerosis (ALS) and Park- inson's dementia (Kurland and Mulder, 1954; Reed et al., 1966; Elizan et al., 1966; Plato et al., 1967). The incidence of ALS on Guam is almost one hundred times higher than that of the continental United States and other parts of the world. As an adjunct to the neurological studies, a series of limited serological and hematological surveys have been conducted (Myrianthopoulos and Pieper, 1959; Tashian et al., 1963; Plato et al., 1964, 1966). The object of the present study is (1) to determine the blood group and haptoglobin frequencies among the Chamorros of Guam and (2) to relate the serological results with the available historical data, in an effort to estimate the magnitude of Spanish, Filipino, and Mexican contribution to the genetic structure of the present hybrid Chamorro population. Historical Notes Guam with an area of 215 square miles is the largest of the Mariana islands in the Western Pacific (Fig. 1). In 1960, the population of Guam was 67,044 (U. S. census report, 1960). Of these, 34,762 were Chamorros, 8,580 Filipinos, 20,724 Caucasians (mostly Americans), and about 3,000 Carolinians from the U. S. Trust Territory of the Pacific. The original Chamorros are presumed to have immigrated to Guam from the Philippines and the Malaysian region in general as early as 1527 ± 200 B.C. (Spoehr, 1957). Their first encounter with the Europeans was in 1521 when Magellan landed in the village of Umatac. In 1565, Guam was officially proclaimed a Spanish territory by Lopez de Legazpi. During the following one hundred years, the island remained in relative obscurity with only occa- sional visits by Spanish and other maritime groups. In 1668, Father Sanvitores and his helpers arrived from Acapulco, Mexico, and established a Jesuit mission. They were accompanied by a few laymen and 32 Spanish and Filipino soldiers. At the time of his arrival, Father Sanvi- tores estimated the native population to have been about 50,000. In 1680, Don Jose DeQuiroga ("the tyrant") was appointed governor of Guam. The arrival of

Received June 6, 1967. 722

AMERICAN JOURNAL OF HUMAN GENETICS, VOL. 19, No. 6 (NOVEMBER), 1967 PLATO AND CRUZ 723

FIG. 1. Western Pacific and Guam (from United States Populations Census for Guam, 1961).

DeQuiroga and his subsequent treatment of the natives sparked a series of Chamorro uprisings in which thousands of the island's inhabitants lost their lives. The Chamorro-Spanish wars together with two strong typhoons and a smallpox epidemic in 1688 contributed to the reduction of the Chamorro population from 50,000 in 1668 to fewer than 5,000 by 1691. The first official census taken by the Spanish in 1710 reported only 3,678 natives living. The population of Guam continued to decline (Fig. 2) until 1783, when there were only 1,500 Chamorros alive (Carano and Sanchez, 1964). The reduction of the native population and the resulting shortage of labor necessitated the importation of large groups of Filipino laborers, most of whom remained on Guam and married Chamorro women. The intermarriage of the Chamorros with Filipinos and Spanish became so extensive that "had it not been for intermarriage between the Chamorros and non-natives, the Marianas might eventually have been depopulated" (Carano and Sanchez, 1964). Since the beginning of the nineteenth century, the population of Guam increased steadily, although the number of pure Chamorros continued to di- minish. By the end of the nineteenth century a new Chamorro population had been established, comprised of an admixture of the original Chamorros with the Filipinos, Spaniards, and Mexicans. This hybrid has remained stable 724 BLOOD GROUPS AND HAPTOGLOBIN ON GUAM

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MATERIAL AND METHODS A total of 343 blood samples were drawn into sterile ampules containing dry EDTA anticoagulant. The specimens were collected from the following districts: Merizo, 70 samples; Umatac, 39; Talofofo, 44; Mangilao, 63; and De- dedo, 94. The remaining 33 samples were drawn from individuals of unspeci- fied residence. Since contingency chi-square tests gave no significant differences among the various subsamples, the data from all districts were pooled. The bloods were typed on Guam using commercial reagents. The anti-Al and anti-A2 were prepared in our laboratory from seeds of Dolichos biflorus PLATO AND CRUZ 725

TABLE 1. ABO BLOOD GROUP PHENOTYPES AND GENE FREQUENCIES AMONG THE CHAMORROS OF GUAM AND IN RELATED POPULATIONS PHENOTYPES GENE FREQUENCIES A1 A2 B 0 A B A B Total p(A) p1(A1) p2(A2) q(B) r(O) Chamorros 99 0 55 169 20 0 343 .183 .183 0 .107 .710 Related Studies Chamorros (Guam), Myrianthopoulos and Pieper (1959) 1497 .180 .119 .701 Chamorros (Saipan), Plato et al. (1966) 142 .139 .139 0 .126 .737 Chamorros (Saipan), Misaitsu (1939) * 132 .219 .124 .657 Chamorros (Saipan), Takasaki (1939) * 293 .198 .082 .720 Filipinos, Fraser et al. (1964) 403 .170 .150 .680 Filipinos, Simmons and Graydon (1945) 382 .152 .181 .671 Mexicans (Mixteco), Rodriquez et al. (1963) 129 .024 .016 .960 Spaniards, Guasch et al. (1952) * 400 .259 .202 .057 .072 .669 * Cited by Mourant et al. (1958). and Ulex europaeus, respectively, and were used exclusively on the A bloods for the A1 and A2 subgroup determinations. The anti-Dia serum kindly was supplied to us by Dr. Miguel Layrisse of Caracas, Venezuela. The haptoglobin determinations were also performed on Guam by starch gel electrophoresis. The blood specimens were typed for the following systems: ABO (including Al and A2), MNS (M,N,S,s,Mg), Kell (K,k,Kpa,Kpb), Kidd (JKb), Duffy (Fya), P, Wra, Vw, and Dia.

RESULTS AND DISCUSSION The phenotypes and the allele frequencies of the various blood groups are presented in Tables 1, 2, 3, and 4. The results of previous blood group studies on the Chamorros are also summarized in these tables together with the available data on the Filipinos, Mexicans, and Spaniards. The Mexicans cited in this report are the Mixtecos who resided in the southwestern part of Mexico near the port of Acapulco (Rodriquez et al., 1963), the origin of most of the trans-Pacific voyages between Mexico and the Philippines. The results of the present survey are in agreement with those of previous studies involving the Chamorros of Guam and Saipan. All samples tested were negative for A2, Kpa, Wra, Vw, and Mg. Two specimens were positive for Kell (K) and all tested positively for Kpb. Besides the absence of A2, other outstanding observations are the high frequency of Dia and the rarity of Rh-negative, with a chromosomal cde frequency of .087. The Du phenotype is also absent. The genes S and Fyb are also rare, with frequencies of .101 and .121, respectively. The high frequency of P2 reported previously among the Saipan Chamorros was substantiated by the present study. The haptoglobin types follow the same general trend found in the Western Pacific and South- east Asia, with a low HpI gene frequency of .37 (Table 5). As seen from Tables 1-5, the frequencies of most of the blood group systems as well as those of the haptoglobins among the Chamorros show an over-all similarity to those of the Filipinos. This similarity stems not only from the 726 BLOOD GROUPS AND HAPTOGLOBIN ON GUAM

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727 728 BLOOD GROUPS AND HAPTOGLOBIN ON GUAM TABLE 5. GENE FREQUENCY OF Hpl AMONG THE CHAMORROS OF GUAM AND RELATED POPULATIONS Number tested HpI Chamorros (Guam), present study 193 .37 Chamorros (Saipan), Plato et al. (1966) 142 .37 Filipinos, Blackwell et al. (1964) 293 .38 Filipinos, Fraser et al. (1964) 403 .39 Mexicans (Zapoteca), Sutton et al. (1960) 80 .53 Spaniards, Planas et al. (1966) 2763 .40 extensive Filipino immigrations to Guam during the Spanish colonial era but also from the original relationship between the ancient Chamorros and the peoples of the Philippines and Malaya. On the other hand, the Spanish element so often cited in the historical literature as a major genetic contributor to the present amalgamated Chamorro population seems to have been over- estimated. Even though the introduction of Kell-positive and possibly the Rh-negative phenotypes may be attributed to Spanish admixture, the present differences in the gene frequency distributions in these systems as well as those of the ABO, MNS, Duffy, and P are too large to suggest a high degree of Spanish admixture. Three critical gene frequencies, A,, cde, and K, were used for estimating the per cent of Spanish-Chamorro admixture, through Bernstein's formula, where per cent admixture = [(q, - Q)/ (q - Q)] X 100 in which q, is the gene frequency of the hybrid population and q and Q are those of the two base populations (Spaniards and Chamorros, respectively). In the use of this formula, it is assumed that the A,, cde, and K gene frequencies of the ancient Chamorros were all zero and that hybridization with the Spanish was the only factor responsible for their present frequencies among the Chamorros (not taking into account possible selection and/or drift). Under these assumptions the per cent of Spanish admixture would have been 0, 24%, and 6% for the A2, cde, and K genes, respectively, with an average of 10%. Since the assumed complete absence of cde among the ancient Chamorros is quite unlikely, in view of its presence (low as it may be) among the Filipinos and other related populations, the aforementioned 10% Spanish admixture should be considered more a maximum value. The third group, the Mexicans, are mentioned as forming a major portion of the Spanish Colonial Army by historians (Spoehr, 1954). Little information is available, however, about their activity or their presence on the island. They were also ignored in several census reports. For example, in 1783, of the total reported population of Guam of 3,231, 648 were reported to have been descendants of Chamorro-Filipino marriages and 818 from Chamorro- Spanish (cited by L. Thompson, 1947). A similar report in 1819 indicates 1,774 Chamorro-Filipinos and 965 Chamorro-Spanish. It is difficult to believe that the Mexican soldiers did not land on Guam with their Spanish and PLATO AND CRUZ 729

Filipino fellow soldiers or that they did not intermarry as freely with the natives as the other two groups. The high frequency of Dia among the Chamor- ros may be attributed, at least in part, to Mexican-Chamorro admixture. A plausible explanation of the historical overestimation of the Spanish admixture and the underestimation of that of the Mexican element may be attributed to the possibility that for most Chamorros and Guam visitors of that time, whoever could not be readily identified in the Spanish army as Filipino was labeled Spanish. It should also be borne in mind that by the eighteenth century a high degree of hybridization existed between the Spanish and Mexican Indians. By the eighteenth century the Spanish in Mexico had been considerably accultur- ated through contact with Mexican Indians. "It seems very likely that many inhabitants of Mexico, Indians, Mestizos and Spanish born in Mexico came to the Marianas" (Spoehr, 1954). It is also possible that in the Spanish Colonial army only a few officers were actually Spanish from Spain. Kotzubue (1821) related that during his visit to Guam in 1817, "the Governor is in fact the only real Spaniard; the other officers and even the priests are natives either of Manila or Mexico: . . . . the town (Agana) contained 1500 inhabitants who derive their origin from Mexico and the Philippines. There is only a man and his wife from the original branch." Such reports indicate that, even though the Mexicans and part-Mexicans were not specifically counted at the time, they were present on Guam and they did intermarry with the natives. The Mexican-Chamorro hybridization may be partly responsible for the high frequency of Dia among the present Chamorros, as stated above, although this hybridization alone could not account for such a high frequency. If the Filipino Dia frequency of .018 is used as a base for the original Chamor- ros, and Bernstein's formula is applied under the earlier assumptions, it would have necessitated over 80% Mexican admixture to raise the Die frequency to its present .089. This high degree of Mexican hybridization is unlikely, and it finds no support from the other blood group frequencies. A more plausible explanation is that the original settlers of Guam have attained a higher Dia gene frequency than that of the Filipinos and other Malayan groups. This might have resulted either by genetic drift acting upon the small immigrant groups that settled on Guam in the pre-Christian times, and enhanced by the Mexican admixture during the Spanish colonization of Guam, or by a selection force that exists or had existed on Guam favoring this gene.

SUMMARY Three hundred and forty-three blood specimens were drawn from native Guamanians (Chamorros) and were typed for the ABO, Rh, MNS, Kell, Duffy, Kidd, P, Wra, Vw, and Diego systems. Haptoglobin determinations also were carried out on Guam by starch gel electrophoresis. The outstanding points of this study are the absence of A2 and the very low frequencies of the Rh-negative, Fy(a-), Kell-positive phenotypes and the presence and rela- tively high frequency of Di(a+). The high gene frequency of P2 reported earlier among the Saipan Chamorros was shown also in the present study. 730 BLOOD GROUPS AND HAPTOGLOBIN ON GUAM The results of the blood group frequencies discussed in relation to the historical reports suggest that the present-day Chamorro population is more closely related to Filipinos than to Spanish or Mexican populations.

ADDENDUM The close ethnic relationship between the Chamorros and the Filipinos has been given additional support by the recent report of Lie-Injo (1967) on the presence of the carbonic anhydrase variant CA Ic among the Filipinos. In a sample of 120 Filipinos residing in San Francisco, she found two with the CA Ic variant. The only other instance of this variant was among the Chamor- ros (Tashian et al., 1963). In that report, two CA Ic individuals were found among the Chamorros of Guam and two in Saipan in samples of 109 and 142, respectively. Among the populations tested for the CA Ic variant with negative results (R. E. Tashian, personal communication) are Caucasian (2,659 samples), American Negro (767), American Indians (Seminoles, 108; Xavante, 265; Yanamana of Venezuela and Brazil, 84), Micronesian from the Caroline Islands (150), and Melanesian of New Guinea (32). REFERENCES BLACKWELL, R. Q., CHEN, H.-H., AND CHEN, H.-C. 1964. Haptoglobin distribution in a Filipino population. Nature 202: 814-815. CARANO, P., AND SANCHEZ, P. 1964. A Complete History of Guam. Rutland, Vermont: Charles Tuttle Company. ELIZAN, T. S., HIRANO, A., ABRAMS, B. M., NEED, R. L., VAN Nuis, C., AND KURLAND, L. T. 1966. The amyotrophic lateral sclerosis/Parkinsonism-dementia complex of Guam. Neurological re-evaluation. Arch. Neurol. 14: 356-368 (April). FRASER, G. R., GIBLETT, E. R., STRANSKY, E., AND MOTULSKY, A. G. 1964. Blood groups in the Philippines. J. Med. Genet. 1: 107-109. KOTZUBUE, 0. VON. 1821. A Voyage of Discovery Into The Sonthseas and Bering Straights. Translated by H. E. Lloyd. London: Longman, Hurst, Rees, Orm and Brown. KURLAND, L. T., AND MULDER, D. W. 1954. Epidemiologic investigations of amyotrophic lateral sclerosis. 1. Preliminary report on geographic distribution with special reference to the Mariana Islands, including clinical and pathologic observations. Neurology 4: 355-378, 438-488. LIE-INJo, L. E. 1967. Red cell carbonic anhydrase Ic in Filipinos. Amer. J. Hum11. Genet. 19: 130-133. MOURANT, A. E. 1954. The Distribution of the Human Blood Groups. Springfield, Illinois: C. C Thomas. MOURANT, A. E., KOPEK, A. C., AND Do\rAXIEWSKA-SOBCZAK, K. 1958. The ABO Blood Groups. Oxford: Blackwell. MYRIANTHOPOULOS, N. C., AND PIEPER, S. J., Jr. 1959. The ABO and Rh blood groups among the Chamorros of Guam: With reference to anthropologic and genetic prob- lems in the area. Amer. J. Phys. Anthropol. 17: 105-108. PLANAS, J., FUSTE, M., VINAS, J., AND IRIZAR, J. L. 1966. Haptoglobin types in the Iberian Peninsula. Acta Genet. Stat. Med. (Basel) 16: 371-376. PLATO, C. C., CRUZ, M. T., AND KuRLAND, L. I. 1964. Frequency of glucose-6-phosphate dehydrogenase deficiency, red-green color blindness and Xga blood-groups among Chamorros. Nature (Lond.) 202: 728. PLATO, C. C., REED, D. M., ELIZAN, T. S., AND KURLAND, L. T. 1967. Amyotrophic lateral sclerosis/Parkinsonism-dementia complex of Guam. IV. Familial and genetic investigations. Amer. J. Hum. Genet. 19: 617-632. PLATO, C. C., RUCKNAGEL, D. L., AND KURLAND, L. T. 1966. Blood group investigations on PLATO AND CRUZ 731

the Carolinians and Chamorros of Saipan. Amer. J. Phys. Anthropol. 24: 147-154. REED, D. M., PLATO, C. C., ELIZAN, T. S., AND KURLAND, L. T. 1966. The amyotrophic lateral sclerosis/Parkinsonism-dementia complex: A ten year follow-up on Guam. 1. Epidemiologic studies. Amer. J. Epidemiol. 83: 54-73. RODRIQUEZ, H., RODRIQUEZ, E. DE, LoRIA, A., AND LISKER, R. 1963. Studies on several genetic hematological traits of the Mexican population. V. Distribution of blood group antigens in Nahuas, Yaquis, Tarahumaras, Tarascos and Mixtecos. Hum. Biol. 35: 350-360. SIMMONS, R. T., AND GRAYDON, J. J. 1945. Blood groups, subgroups, M, N types and Rh subtypes in Filipinos. Med. J. Australia 11: 325-328. SPOEHR, A. 1954. Saipan, The Ethnology of a War-Devastated Island. Chicago: Chicago Natural History Museum. SPOEHR, A. 1957. Marianas prehistory: Archaeological survey and excavations on Saipan, Tinian and Rota. In Fieldiana: Anthropology, Vol. 48. Chicago: Chicago Natural History Museum. SUTTON, H. E., MATSON, G. A., ROBINSON, A. R., AND KOUCKY, R. W. 1960. Distribution of haptoglobin types among Indians of Southern Mexico and Guatemala. Amer. J. Hum. Genet. 12: 338-347. TASHIAN, R. E., PLATO, C. C., AND SHOWS, T. B., JR. 1963. Inherited variant of erythrocyte carbonic anhydrase in Micronesians from Guam and Saipan. Science 140: 53-54. THOMPSON, L. 1947. Guam And Its People. Princeton, New Jersey: Princeton University Press.