MOLECULAR CHARACTERIZATION OF Hb D-PUNJAB [β121(GH4)Glu→Gln] IN THAILAND

Abstract

We describe the hematological and DNA characterization of Hb D-Punjab [β121(GH4)Glu→Gln] in Thailand. Nine patients from five unrelated families were studied; four patients were simple carriers of Hb D-Punjab, two were compound heterozygotes for Hb D-Punjab/β⁺-thalassemia;another two patients were double heterozygotes for Hb D-Punjab and α-thalassemia-2, and one patient was a compound heterozygote for Hb D-Punjab and Hb E [β26(B8)Glu→Lys]. Typical thalassemic indices with hypochromic microcytosis were observed in compound Hb D-Punjab/β⁺-thalassemia and Hb D-Punjab/Hb E but normal hematological profiles were observed in the remaining cases. DNA sequencing of the β-globin gene identified the G AA→C AA substitution at codon 121 causing Hb D-Punjab in all cases, and the −28 (A→G) mutation for the β⁺-thalassemia alleles. β-Globin gene haplotype analysis demonstrated, for the first time, that all these Asian β^D-Punjab globin genes were associated with haplotype [−++−+++], previously undescribed in other populations. The finding of Hb D-Punjab in Thailand is compatible either with an independent origin of this abnormal hemoglobin or a spread of the Hb D-Punjab gene with a single origin among Asians.