Mild beta-thalassemia intermedia caused by compound heterozygosity for (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia and molecular characterization of the defect in four Chinese families

Abstract

Molecular characterization of the compound heterozygous condition - (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia - in four families showing mild beta-thalassemia intermedia was carried out using DNA amplification techniques. Using the Amplification Refractory Mutation System (ARMS) to confirm the beta-mutations and DNA amplification to detect the 100-kb Chinese-specific (G)gamma((A)gammadeltabeta)(o)-deletion, ()two families were confirmed to possess (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia with the IVSII No. 654 beta(+)-allele. In the third family, the (G)gamma((A)gammadeltabeta)(o)-deletion was confirmed in the father and the mother was a beta-thalassemia carrier with the cd 41-42 beta(o)-allele. Their affected child with (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia was found to be transfusion dependent. The same (G)gamma((A)gammadeltabeta)(o)-deletion and beta-thalassemia (cd 41-42) was also confirmed in a fourth family. In addition, the mother was also diagnosed with Hb H disease (genotype -alpha(3.7)/-(SEA)). Both the children were found to possess (G)gamma((A)gammadeltabeta)(o)/beta-thalassemia but they were not transfusion dependent and this could be due to co-inheritance of alpha-thalassemia-2 (genotype-alpha(3.7)/alphaalpha) in the children together with their compound heterozygous condition.