Beta-globin haplotype and XmnI polymorphism at position G (gamma)-158 and HbF production in Fanconi's anemia.

BACKGROUND

Patients with aplastic anemia show to a variable degree an increase of the red blood cell volume and percentage of HbF. The extent of HbF reactivation in sickle cell anemia and thalassemia major is related to the presence of XmnI polymorphism at -158 G (gamma). In this study, we have investigated whether in Fanconi's anemia the increase of the HbF is also related to the XmnI polymorphism.

METHODS

Restriction site polymorphisms in the beta-globin gene cluster were analyzed to define the beta-globin haplotype. The presence of a C --> T substitution at position -158 G (gamma) was investigated by XmnI digestion.

RESULTS

We found that patients with the XmnI site at -158 G (gamma), which was contained either in the 5' -+-++ or in the rare -+--- sub-haplotype, tend to have higher HbF and MCV values. The differences between XmnI positive and XmnI negative patients were highly significative (p less than 0.0025) for the MCV values, but barely significant for HbF levels (p less than 0.05).

CONCLUSIONS

Our results suggest that in Fanconi's anemia both the extent of HbF reactivation and the fetal-like erythropoiesis, which is responsible for high MCV, are at least partially related to the beta-globin haplotype.