Haplotype VI associated beta + thalassaemia intermedia. First Italian case.

We report the study of a family originating from eastern Sicily with mild beta thalassaemia intermedia which is similar both at a molecular level and in clinical form to that called "beta + thalassaemia intermedia-Portuguese type". Our patients were homozygous beta + thalassaemics with high HbA2 and low HbF levels. The mild clinical course was as a result of their age and because regular blood transfusion was established only in adulthood. All of the heterozygote parents were asymptomatic with a blood picture and haemoglobin pattern typical of beta thalassaemia. Studies at a molecular level revealed no abnormalities in the beta-like globin gene cluster and excluded the presence of a deletional form of alpha thalassaemia. Restriction enzyme site polymorphisms around the beta gene cluster showed that all patients were homozygous for the haplotype described as VI. Comparison of these homozygous haplotypes with the Portuguese ones revealed a clear difference in the polymorphic Pvu II site. In all Sicilian homozygous cases, this site was present on one chromosome and absent on the other. Therefore our hypothesis is that Portuguese beta + thalassaemia intermedia is different from the Sicilian type.