Blood group polymorphisms in Brazil☆

the frequencies of the different blood group antigens vary sigBlood group antigens are polymorphisms of proteins and carbohydrates on the surface of red blood cells (RBC) with the distribution of alleles varying between different ethnic groups and populations. By using the genetic information provided by the human genome project, the molecular basis of most blood group genes encoding blood group systems, antigens and phenotypes have been elucidated and nowadays the molecular basis is known for the 308 antigens clustered in the 36 blood group systems recognized by the International Society of Blood Transfusion (ISBT).1 This knowledge has provided the means to predict red cell antigens and phenotypes in order to identify more extensively matched blood for chronically transfused patients. However, data on the prevalence of various blood group antigens in different populations are essential for estimating the availability of blood components. The available wealth of serologically defined variants has contributed to the rapid rate with which the genetic diversity of blood group genes has been revealed. Initially, molecular information associated to each variant was obtained from only a small number of samples and applied to DNA analysis with the hopeful assumption that the molecular analysis would correlate with RBC antigen typing. By gathering more information, it became obvious that many molecular events result in the genotype and RBC phenotype being apparently discrepant.2 Therefore, a large number of people from a variety of ethnic backgrounds need to be studied to determine the occurrence of particular genotypes and to establish more reliably the correlation between blood group genotype and phenotype. Hemagglutination has identified many phenotypic variants and molecular analysis has revealed remarkable variations within variants. Investigations on the automation of SNP