The expanding spectrum of thalassemia intermedia

The hemoglobin disorders serve as a model for study of the genetic heterogeneity underlying the phenotype of genetic disorders. 'Thalassemia intermedia' is a clinical phenotype which displays marked genotypic variability in different populations or ethnic groups. Two common underlying mechanisms include co-inheritance of alpha globin gene deletions in homozygous thalassemia intermedia and presence of XmnI polymorphism. The newly described mechanisms including unstable hemoglobin disorders and somatic deletions in beta-globin gene are elaborated in the present review.