Abstract
Structural analysis documented the presence of haemoglobin LeporeWashington (=LeporeBoston) in a Greek Cypriot family and provided further evidence that, of the various types of Lepore mutants, only one is common in the Mediterranean area. Two individuals in this family were heterozygous for both Hb Lepore and beta thalassaemia, but they exhibited striking differences in the clinical severity and course of the disease. The data illustrate that additional environmental or genetic factors play roles in determining or modifying the pathophysiological consequences of highly specific molecular defects and, thus, their ultimate clinical phenotypes.