[Hemoglobin S haplotypes: their epidemiologic, anthropologic and clinical importance]. / Haplotipos de la hemoglobina S: importancia epidemiológica, antropológica y clínica.

The link between beta s-gene haplotypes and sickle cell anemia has permitted a better understanding of the biological manifestations of this disease. The use of better laboratory methods can help rule out other hereditary factors that can camouflage the real hemoglobin genotype. The clinical heterogeneity of sickle cell disease, which is characterized by the presence of S hemoglobin, can be explained in terms of fetal hemoglobin (HbF) levels, ratio of G gamma chains to A gamma chains, 2,3-diphosphoglycerate levels, linked mutations, beta s haplotypes, coexistence of alpha-thalassemia, and environmental factors. The inheritance of Sen and Arab/Indian beta-gene cluster polymorphisms is associated with a milder clinical course, whereas the Central African Republic (CAR) or Bantu, Cameroon, and Benin haplotypes are linked with severe sickle cell disease. The CAR haplotype carries the worst prognosis of all (less than 12% HbF levels and adult-type G gamma:A gamma ratio). Once characterized, these DNA polymorphisms also assume great importance as anthropologic and genetic markers. In America, beta s haplotypes are contributing to a better understanding of Black American roots and their African ancestry. There is ample evidence of genetic variability not only between different Black populations in America, but also within the same country, as is the case in Costa Rica.

[Structural variants of hemoglobin in Ibero-America]. / Variantes estructurales de la hemoglobina en Iberoamérica.

Structural hemoglobin variants are reviewed for Iberoamerica; specially in Latin America, they reflect racial composition and geographic origin. Latin American genetic composition is a function of ethnic composition in each country (mainly Africans and Spaniards, and the "indians" or native peoples). For this reason the distribution of hemoglobin variants has been greatly affected by the individual and population movements, specially as a result of the 18th and 19th century African slave trade. Scientific, sanitary, social and cultural factors explain (at least for Latin America and Portugal), a quantitative and qualitative subestimation of the structural variants of hemoglobin. In Spain, which has extensive research on the subject, the Caucasian variant number is known to be high, compared with Latin America and Portugal. Concerning origin and prevalence of hemoglobin polymorphism, the only established positive selection force is malaria falciparum. In Iberoamerica, the Hb S, as the major polymorphism and the HbC, have the greatest clinical and anthropological importance. Nevertheless, most variants are rare (found in an individual person or a particular family). Other minor Iberoamerica polymorphisms are the Hb E and D-Punjab, from Asia; and the Hb Korle-Bu, G-Philadelphia and A2 from Africa.

[Hemoglobinopathies in Caribbean Basin countries]. / Hemoglobinopatías en los países de la Cuenca del Caribe.

A review of hemoglobinopathies in the Caribbean basin, shows a clear association with race: In Costa Rica, evidence suggests two geographic origins for populations of African origin.