Review: the Diego blood group system The purpose of this article is to review the literature Caribe Indian admixture. The fifth example was a nat- about the Diego blood group system and to highlight urally occurring anti-Dia in a Caucasian woman, anthropological studies, genetic studies, serologic whose serum agglutinated RBCs from a Di(a+) blood characteristics of Diego antigens and antibodies, and donor. Four of her relatives of Irish origin were their clinical importance in certain ethnic groups. Di(a+). The next example of anti-Dia in an Austrian family, caused HDN and was the first example in History and Anthropological Studies which alloimmunization occurred during a first preg- In 1956 a low-incidence red cell antigen responsi- nancy.1,2,5-7 It was concluded from these studies that ble for hemolytic disease of the newborn (HDN) was Dia is not exclusive to Mongoloids but occurs also as described with the aid of an antibody produced by a a low-incidence antigen in Caucasians. mother living in Caracas, Venezuela. This antigen was Since American Indians are considered to be named Diego (Dia) after the proposita, and the corre- anthropologically related to the Mongoloid people, sponding antibody was named anti-Dia.1 A study of individuals of Chinese and Japanese descent living in the Diego family showed that the antigen was present Venezuela were studied. The presence ofDia in six in 10 of 33 members in four generations (see Fig. South American Indian populations studied, as well 1).1-3 During this study it was observed that some as in Chinese and Japanese, suggests that this gene is family members showed physical features of admix- Mongoloid rather than American Indian. Further find- ture with native Indians, many of whom are Di(a+).4 ings of the Dia antigen in Chippewa Indians in The Dia antigen may not be completely absent in a Northern Minnesota and in Japanese in Winnipeg also Caucasian population free from admixture with suggested that Dia may be an Asiatic (Mongoloid) Indians, since the second example of anti-Dia was characteristic.3 The phenotype and genotype fre- found in the serum of the mother of an infant with quencies of the Diego system in Mongoloid, HDN from a Polish family living in New York.1,2,5 Caucasian, Negroid, and hybrid Venezuelan popula- Some believe that the finding of anti-Dia in a Polish tions are given in Table 1.3,8 mother and the Dia antigen on the red cells of her In 1956 it came as a surprise when no Di(a+) per- husband, who is also Polish, is indicative of son was found among 156 Eskimos tested in the Mongoloid admixture, and the high incidence of the Eastern Canadian Arctic.9 Further studies on Eskimo B gene in the Polish population is supportive evidence populations showed a very low incidence of Dia.10-12 of this admixture.3,4It was proposed that if the genet- The Alaska Indians are the only American Indians that ically related Dib and anti-Dib exist, the antibody do not have at least 5 percent Di(a+) person13 In should be sought among the homozygotes of geno- the study of the Canadian Indian population by type DiaDia of the Caribe Indians.' Buchanan et aI.,13 the Dia antigen incidence The third example of anti-Dia also caused HDN, this decreased from 3 percent in northern Alberta to 0 per- time in a family of Spanish ancestry, "Mart," living in cent in Inuvik in far northern Canada. Other studies the Dallas, Texas, area. The fourth example of anti-Dia found that the incidence of Dia was 3-4 percent in was described in a Puerto Rican woman, whose pre- northern Japan and 5-7 percent in southern maturely born twins did not develop HDN, although All of these studies suggest that Dia is an their red blood cells (RBCs) were direct antiglobulin Asiatic characteristic. test (DAT) positive. In this family there were six Nearly 1374 Australian aborigines and 1741 New Di(a+) members in four generations, and there was Guineans were tested for Dia from 1967 to 1970 and IMMUNOHEMATOLOGY, VOLUME 9, NUMBER 2, 1993 35 M. ZAFAR AND M.E. REID all were negative, indicating the absence or very low ed by Tartars during the 13th as well as the 15th to incidence of this antigen in these racially distinct pop- 17th centuries. Therefore, admixture with Mongoloid ulation~.~'In 1986 a study by Edwards-Moulds and genes in this population cannot be excluded. Alperin18 showed a high incidence (14.7, 8.2, and 8.9%) of Dia in three Mexican-American communities Terminology in Texas, probably reflecting their Indian ancestry. Of A summary of the phenotypes, genotypes, antigens, 4225 Mexican-Americans tested, six were negative for and antibodies of the Diego blood group system is Dib (the antithetical high-incidence antigen), giving given in Table 2. The terminology recommended by the Di(a+b) phenotype an incidence of 0.14 percent. the International Society for Blood Transfusion (ISBT) The calculated gene frequencies were 0.05-0.08 for is shown in Table 3. Dia and 0.92-0.96 for Dib. l8 In 1990 a study by Lee et al.19 showed that Diego typing of the Chippewa Genetics tribe in Minnesota had patterns similar to those Studies on the inheritance of Dia, conducted in the reported in other North American Indian populations. original Diego family and 40 other Indian and hybrid In 1992 a study from Poland showed that the inci- families, showed that the antigen is inherited as a dence of Dia in the southeastern region of Poland dominant character with no linkage either to the sex (0.91%) is greater than in the western region chromosome or to the following red cell antigens: (0.25-0.37%).20The southeastern region was invad- ABO, MNSs, Kk, Fya,jka, Lea, and P.1,3,13,14,21 Astudy I. II. 1 4 5 6 I III. 1 2 3 4 5 6 7 8 9 10 11 IV. 123 456 7 8 9 10 11 12 13 14 positive negative not studied propositus deceased Pig. 1. The Diego family tree carrying the Dia antigen 36 IMMUNOHEMATOLOGY, VOLUME 9, NUMBER 2, 1993 Review: the Diego blood group system Table 1.The phenotype and gene frequencies of Dia and Dib in Mongoloid Caucasian, Negroid and hybridVenezuelan populations Phenotype (%) Gene frequencies (%) Number Populations tested Di(a+) Di(a-) Dia Dib Kaingangues Indians (Brazil) 48 45.83 54.17 26.44 73.56 Carajas Indians (Brazil) 36 36.11 63.89 20.07 79.93 Caribe Indians (Venezuela) 170 29.41 70.58 16.00 84.00 Guanibo Indians (Venezuela) 76 14.47 85.52 7.50 92.50 Piaroa Indians (Venezuela) 24 12.50 87.50 6.50 93.50 Japanese 65 12.30 87.70 6.39 93.61 Chippewa Indians (Canada) 148 10.81 89.19 5.56 94.44 Japanese (Canada) 77 7.79 92.21 5.55 94.45 Negroid (Curiepe, Venezuela) 150 7.33 92.67 3.74 96.26 Ciudad Bolivar Indians 100 7.00 93.00 3.57 96.43 Arawaco Indians (Venezuela) 152 5.26 94.73 2.80 97.20 Chinese (Canton) 100 5.00 95.00 2.54 97.46 Negroid (Yaracuy, Venezuela) 119 3.36 96.64 2.70 98.30 Barcelona 61 3.28 96.72 1.65 98.35 CaracasIndians 500 2.00 98.00 1.01 98.99 Pregonero Indians 148 0.67 99.33 0.34 99.66 Poles (1992) 9661 0.46 99.54 0.71 99.29 Poles (1957) 200 0.00 100.00 0.00 100.00 Americans (U.S.) 1000 0.00 100.00 0.00 100.00 Italians 400 0.00 100.00 0.00 100.00 Spaniards 400 0.00 100.00 0.00 100.00 Dutch 200 0.00 100.00 0.00 100.00 Russians 200 0.00 100.00 0.00 100.00 Hungarians 200 0.00 100.00 0.00 100.00 Note: Further population studies can he found in: Mourant AE, Kopec AC, Domaniewska-SobczakK. The distribution ofthe human blood groups. 2nd ed. London: Oxford University Press, 1976. of Indian families by Allen22 showed no close linkage Table 2. The Diego blood group system between the genes forDia and those for ABO, Rh, MN, P, Kpa Duffy, or Lewis. Chown et al.23 also showed Classification Symbols that Dia segregates independently from Fya and Fyb. Genes Dia andDib Laryrisse et al.24 showed that the Diego locus, if on the Genotypes Dia/Dia Dia/Dib Dib/Dib Phenotypes Di(a+b-), Di(a+b+), Di(a-b+),Di(a-b-)* same chromosome as any of the ABO, MNSs, P,Jsa and Antibodies anti-Diaand anti-Dib Rh loci, was not within measurable distance of them, *Not found yet nor, if the Diego locus was on the homologous part of the sex chromosomes, was it in measurable distance Table 3. ISBT terminology for the Diego blood group system* of the beginning of the nonhomologous region. The Diepo blood group system ISBT terminology simultaneous occurrence of Dia and Mia in a Japanese family has permitted a definite interpretation of their Symbol DI System number 010 independent segregation.25 Alter and co-workers26 Antigen Dia number 010.001 reported the occurrence of three uncommon anti- Antigen Dib number 010.002 gens, Dia, Kpa, and Goa, in a single Puerto Rican indi- *Blood Group Terminology 1990 published in Vox Sang 1990;58:152-69. vidual. A family study did not reveal evidence of linkage with any of the blood group systems.