Genetic modifying factors in beta-thalassemia

The beta-thalassemia is probably the most extensively studied genetic disea se. Essentially any molecular defect that has been first described in assoc iation with the globin genes has been later implicated as a molecular deter minant of newly discovered genes. Accordingly, the thalassemias have always represented a model genetic disease, especially in relation to the develop ment of programs for population screening, genetic counseling and prenatal diagnosis. Here we will review the present knowledge on the genetics of tha lassemia and of the relevant modifying factors. Major categories of the car rier state, the genotypes, the clinical phenotypes and the correlation betw een genotype and phenotype will be discussed.