Genetic-epidemiological Study Of Hemoglobin S In A Population From Southeastern Brazil [estudo Genético-epidemiológico Da Hemoglobina S Em Uma População Do Sudeste Do Brasil]

摘要

Sickle cell anemia, the clinical expression of individuals homozygous for the hemoglobin S gene, is the most frequent hereditary disease in Brazil. Nevertheless, a genetic-epidemiological approach is rarely used in Brazilian studies related to this alteration. In the present study, using a specific computer program, data from 817 (513 males and 304 females) non-consanguineous individuals heterozygous for the hemoglobin S gene were studied. The participants, with ages varying from 18 to 65 years old, live from the region of Campinas, Southeastern Brazil. The Caucasoid, Negroid and native Indian genomic backgrounds of this sample were evaluated by a study of allelic frequencies for the ABO blood group system and compared with those observed in the general population from the same city. Data analysis showed that: 52% of the hemoglobin S carriers had African ancestry as shown by their phenotypes and that 36% of the subjects came from North-eastern Brazil, most from the state of Bahia (15%). This internal migration tends to decrease the proportion of the hemoglobin S Bantu (wild) haplotype in the region of Campinas, by increasing the proportion of the Benin haplotype (milder). The frequencies of this sample were Negroes 45%, Caucasians 41%, and native Indians 14%. This genomic constitution is significantly different from that observed in the general population from the same city with greater frequencies of Negroes and native Indians and a lower frequency of Caucasians. Migration from the northeastern and miscegenation have significantly altered the genetic-epidemiological profile of hemoglobin S carriers in the region of Campinas.