Recent Studies on the Abnormal Hemoglobins found in Thailand

Abstract

Numerous abnormal hemoglobins (Hb) have been discovered in Thailand, and yet further studies continue to show additional variants not previously described. This paper reviews the discovery of two more variants, as well as additional studies on families with unusual combinations of mutations. One proposita had an abnormal Hb with similar electrophoretic mobility to Hb J Bangkok, but tryptic peptide mapping by h.p.l.c., amino acid analysis and protein sequence analysis revealed an abnormal peptide α-T9, due to the mutation [α61 Lys-Asn], previously found in Hungary and identified as Hb J Buda. Direct DNA sequence analysis confirmed this result, and showed that the mutation occurred in the α1 gene and not the α2-gene. The abnormal Hb in another proposita was shown by peptide mapping, protein sequence analysis, and DNA sequence analysis, to be identical to Hb G Coushatta [β22 Glu-Ala]. In addition to the above variants, unusual combinations of mutations from two other families were studied, namely the combination of Hb E (common in Thailand) with Hb C (common in African populations) and the combination of Hb E/β17-thalassemia/β41-42-thalassemia.