HIGH HBF IN PREGNANCY IS ASSOCIATED WITH THE XMN-I POLYMORPHISM AT THE -158BP OF THE G-GAMMA-GLOBIN GENE

HbF was measured in the peripheral blood of 354 women during the first trimester of pregnancy. In those (n = 6) with HbF > 3% and in 30 rand omly selected pregnant women with normal HbF values, analysis of the G gamma content and the Xmn I polymorphism was performed. The frequency of the Xmn I polymorphism was significantly higher (P < 0.001) in the group with high HbF (0.67) compared to the control group (0.10). The G gamma chain content evaluation revealed a newborn ratio in all 6 hig h HbF subjects. Six months after delivery, HbF was measured in all wom en with high HbF during pregnancy, revealing normal values. These resu lts suggest that the presence of the Xmn I polymorphism is a strong in ducer for the elevation of HbF during pregnancy.