[First example of Hb lepore Washington-Boston trait in a Japanese].

An abnormal hemoglobin (Hb) found in a 63-year-old Japanese woman presenting with asymptomatic chronic microcytic anemia was extensively characterized by the conventional protein chemistry, restriction mapping of the genomic DNA with Bgl II digestion, and direct sequencing of a relevant segment of the mutant non-alpha-globin gene. The results identified a hybrid globin with delta- and beta-like sequences, from position 1 to 87 and from 105 to 146 (C-terminal), respectively. The delta beta fusion gene was produced by deletion of 7.4 kb involving parts of the two closely linked genes. The break point was somewhere within the homologous 58 bps, from codon 88 to IVS-II-7. The same deletion had repeatedly been reported in Hb Lepore Washington-Boston. The expression of a mild (delta beta)(+)-thalassemia trait in the present case completely agreed with previous reports on representative Hb Lepore heterozygotes. The basis for the activity of Hb Lepore gene which is several times higher than the delta-globin gene was discussed.