The molecular basis of HbH disease in Greece.

Globin gene mapping in 16 Greek individuals with HbH disease and their parents has demonstrated the occurrence of several HbH genotypes brought about by the interaction of two alpha zero-thalassaemia and two alpha+-thalassaemia haplotypes. Eight of the 16 patients had the genotype - -Med/-alpha 3.7, four the genotype -(alpha)20.5/-alpha 3.7 and three the genotype - -Med/alpha alpha T. In one patient the restriction data are consistent with two possible genotypes alpha alpha T/alpha alpha T or - -/alpha alpha T. It is demonstrated that HbH disease in Greece is heterogeneous, with the deletion haplotypes - -Med and -alpha 3.7 being more prevalent than the -(alpha)20.5 and non-deletion (alpha alpha T) haplotypes.