The clinical phenotype of β and δβ thalassemias in Greece

Abstract

Based on precise evaluation of hematological findings and clinical manifestations, the relationship between genotype and clinical phenotype was studied in 475 Greek patients with β and δβ thalassemias. Almost all known genotypes are included in this series, but the most frequent was homozygous β^th high A₂ (71.6%), β^th/β^th silent (7.4%), β^th/δβ^oth high F (6.3%) and β^th/β^th Dutch (6.3%).

In general, the phenotype was related to the genotype, though clinical heterogeneity was detected among patients with the same genotype. The severe type of thalassemia major was most commonly found in homozygous β^th patients mainly of β^o/β^o and β^o/β⁺ genotypes while homozygous β⁺ patients had milder clinical manifestation. Furthermore a small group of patients, characterized as homozygous β⁺⁺ (HbF<30%) had mild thalassemia intermedia. In addition mild thalassemia intermedia was principally related with homozygous δβ^oth, and compound heterozygous β^th/β^th silent I, and less frequently with other genotypes such as compound heterozygous with β^th/β^th Dutch, β^th/β^th silent II, β^th/δβ^th high F or Lepore.

It was shown that precise genetic characterization and clinical evaluation is of primary importance in predicting the prognosis and formulating the proper treatment for the individual patient with thalassemia.