Distribution of abnormal hemoglobins and glucose-6-phosphate dehydrogenase variants in 1200 school children of Bahia Brazil.код для вставкиСкачать
AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 53509-512 (1980) Distribution of Abnormal Hemoglobins and Glucose-6Phosphate Dehydrogenase Variants in 1200 School Children of Bahia, Brazil ELAINE s.AZEVEDO, AURISTELA F.P. ALVES, MARIA CHRISTINA B. OLYMPIO DA SILVA, MAlUA DAS GRACAS F. SOUZA,-ANGELA MARIA V. MUNIZ DIAS LIMA, AND WIGBERTO CUNHA AZEVEDO Laborakjrio de Genhtica Mhdica, Hospital Prof. Edgard Santos, Universidade Federal da Bahia, 40.000 Salvador, Bahia, Brasil KEY WORDS Bahia, Brazil Race admixture, Hemoglobin, GGPD, ABSTRACT School children from Bahia, Brazil were studied for hemoglobin and glucose-6-phosphate dehydrogenase electrophoretic variants. Eighty-nine heterozygotes Hb AS and 41 Hb AC were identified out of 1200 children. In a subsample of 369 male children there were 38 Gd A-, 38 Gd A, and six Gd Med. An example of Gd MG was identified and evidence is added to the suggestion that this allele is not rare in Brazil. Hemoglobin (Hb) and glucose-6-phosphate dehydrogenase (G6PD)genetic systems are two commonly studied human polymorphisms in many parts of the world. In Bahia, however, the frequency of G6PD alleles has never been investigated a t a population level (AzevGdo and Azevgdo, 1974; Azevgdo et al., 1978), and the hemoglobin variants have been studied mainly on hospital samples (Kalmus, 1957; Machado, 1958;Peixoto et al., 1963;Ramos and Pedreira, 1970; Ramos et al., 1975). In the present study we report the results of a survey for abnormal Hb in 1200school children and the findings for G6PD gene frequencies in a subsample of 369 male children. ORIGIN OF SAMPLE School children from first degree public school in Salvador, capital of the State of Bahia, were asked to cooperate for the study. Because all those attending public schools in Brazil pay no fee, the children there are mainly from low socioeconomicclasses, which represent not only the largest classes in the city but also those having more Black admixture. RACIAL ADMIXTURE To assess the proportion of Black admixture the children were subjectively classified racially as described by Krieger et al. (1965).Skin color, hair type, and facial features were the variables considered for assigning a child to one 0002-9483/8015304-0509$01.10C 1980 ALAN R. LISS. INC. of the following groups: White, light mulatto, medium mulatto, dark mulatto, Black, light Indian, and dark Indian. LABORATORY PROCEDURES Venous blood samples were drawn in the school itself and refrigerated during transportation to the laboratory located in the same city. Starch gel electrophoresis (Smithies, 1955) prepared with Brazilian starch (Carvalho and Azevgdo, 1976)was used for both Hb and G6PD studies. A discontinuous buffer system pH 8.6 (Poulik, 1957) was used for Hb, while G6PD was run in phosphate buffer pH 7.0 (Fildesand Parr, 1963).All electrophoresis was carried out a t 4°C. The G6PD zone of activity was developed by incubating the sliced gel with an agar overlay containing the specific reaction mixture (Boyer et al., 1962). RESULTS Out of 1200 school children 89 were heterozygotes Hb AS and 41 heterozygotes Hb AC giving the following gene frequencies: 0.946 forHb A, 0.037 forHb S, and 0.017 forHb C. The overall genotype frequencies and test for Hardy-Weinberg equilibrium are given in Table 1. The racial groups’ distribution and the frequency of heterozygotes Hb AS and Hb AC Received December 3, 1979; accepted May 16, 1980 510 E.S. ME-DO within each group are given in Table 2. Out of 369 male children 45 (0.122) had G6PD deficiency. The overall distribution of G6PD genotypes by racial groups is shown in Table 3. ET AL. Racial intercrosses between Blacks and Whites in Bahia is well known in the past and present. As a result, data from the national census of 19501 showed that 29.6%of Bahia’s population was White, 51.wo mulatto, and 19.Z0 Black (Salzano and Freire-Maia, 1970). However, as shown in the present paper, the so-called White group is the least Black. The frequencies of H b S, H b C, Gd A, and Gd Aalleles increase from White to Black, keeping well-balanced frequencies in the light, medium, and dark mulattoes (Tables 2 and 3). All the presently available data on abnormal hemoglobin in Bahia are summarized in Table 4. DISCUSSION Black Africans constituted the major racial group in the formation of Bahia’s population. Allowing for many historical uncertainties a total of 1,200,000 slaves is estimated to have been imported to Bahia from 1678 to 1851 (Verger, 1976). However, other historians believe the slave traffic to Brazil began as early as 1530 (Boxer, 1969). lUnfortunately, the 1960 and 1970 census did not classify for race. TABLE 1 . Hemoglobin genotypes and gene frequencies in 1200 school children of B a h q Brazil and expected numbers under Hardy-Weinberg equilibrium Observed Freq ~- n Genotypes HbAA Hb AS Hb AC Hbsc Hbss Hb cc Total Expected -~ - ~ Freq n 1070 89 41 0 0 0 0.8916 0.0742 0.0342 0.0000 0 . m 0 . m 1073.88 84.00 38.64 1.44 1.68 0.36 1200 1.0000 1200 (p’) (2pq) (2pr) (2qr) (q2) (4’) Gene frequencies 0.8949 0.0700 0.0032 p = 0.946 (Hb A) q = 0.037 (Hb S ) r = 0.017 (Hb C ) 0.0012 0.0014 0.0003 1 .oooo 1.000 TABLE 2 Racial group distribution and frequency of abnormal hemoglobin within groups in 1200 school children of Bahia, Brazil School children Racial groups ~~ HbAA - .~ Freq Freq n 2 0.113 0.154 0.314 0.239 0.178 0.002 127 169 341 258 173 2 1200 1.000 1070 n n Hb AS Freq ~ n Hb AC Freq ~- White Light mulatto Medium mulatto Dark mulatto Black Dark Indian Totals 136 185 376 287 214 0.934 0.914 0.907 0.899 0.808 1.000 6 12 20 21 30 0 0.044 0.064 0.055 0.073 0.140 0.000 3 89 4 15 8 11 0.022 0.022 0.040 0.028 0.052 0 0.000 41 TABLE 3. Glucose-6-phosphate dehydrogenase (G6PD) gene frequencies by racial groups in 369 male school children o f Bahia. Brozil Male school children n Freq. White Light mulatto Medium mulatto Dark mulatto Black Dark Indian 32 61 128 Totals 369 0.087 0.165 0.347 90 0.244 57 0.154 1 0.003 1.000 n GdB Freq. 28 0.875 52 0.852 98 0.766 66 0.733 40 0.702 1 1.OOO 285 n Gd Med Freq. Gene frequencies GdA Gd An Freq. n Freq. 1 0.031 - - 5 0.039 5 14 - 11 7 - - 6 ‘One fully deficient and other migrating hke Gd MG (AzevOdo and Yoshida, 1969). 1 - 38 0.031 0.082 0.109 0.122 0.127 - 2 4 11 13 8 - 38 0.063 0.066 0.086 0.145 0.140 - n - 2’ 2 Gd? Freq. - 0.035 - HB S AND G6PD IN BAHIA, BRAZIL 511 The frequency of H b AS phenotype varies around 6% in all studies but one. It is possible that the unique finding of 16% sicklers in a sample of 70 is biased due to the sample size. The finding of Gd Med in the present study is explained by European migration other than Portuguese. For example, 1,500,000 Italians migrated to Brazil in the period 1884-1944 (Salzano and Freire-Maia, 1970). Because these migrations are rather recent the Gd Med allele is more frequent in the less Black, a s shown in Table 3. G6PD deficiency was found in combination with hemoglobin S in five cases. Considering the isolated genotype frequencies the expected number of double carriers was three, giving a n observediexpected ratio of 1.7. This finding is in agreement with those reported by Salzano et al. (1968)of no evidence for interation between the Hb and the G6PD polymorphisms. Finally, the finding of a Gd MG-like G6PD variant adds more evidence that this allele is not rare in Brazil. In the first reported Gd MG, the proposita was a female homozygote Gd MGIGd MG, which led to some discussion as to whether this genotype was formed due to inbreeding or to a polymorphism (Azevgdo and Yoshida, 1969). Subsequently, another carrier of Gd MG was identified in South Brazil (Hutz et al., 19771, and very recently we found another example of G d MG i n t h e island of Itaparica off the coast of Bahia. I I I I 0 m 2 ACKNOWLEDGMENTS We are very thankful to CNPq i n Brazil and to OEA for financial support, and to Vanilson Silva and M.A. Machado for technical help. d m 8 LITERATURE CITED m 0 2 8 N f bC ... - 4 E 2 B b s *g 1 F Azevzdo, ES, and Azevedo, TFS (1974) Glucose-6-phosphate dehydrogenase deficiency and neonatal jaundice in Bahia, Brazil. Ci. Cult., 26:1044-1047. Azevao, WC, Silva, MCF, Grassi, MCB, and Azevedo, ES (1978) Deficiencia de glucose-6-fosfato desidrogenase em pacientes de um hospital geral de Salvador, Bahia. Rev. Bras. Pesq. Med. Biol., 11:49-52. Azevzdo, ES, and Yoshida, A (1969) Brazilian variant of glucose-6-phosphate dehydrogenase (Gd Minas Gerais). Nature, 222t380-382. Boxer, CR (1969) The Portuguese Seaborne Empire 14151825. 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