Compound Heterozygous Hb Tak/Hb E Causes Secondary Erythrocytosis in a Thai Family

Abstract

 Hb Tak is a rare cause of secondary erythrocytosis. It results from the insertion of two nucleotides (AC) at the termination codon between codon 146 and codon 147 of the β-globin gene. This insertion causes a frameshift in the terminating codon 147 resulting in an elongated β chain with an impaired formation of the T-state. We report a Thai family with a compound heterozygosity for Hb Tak [β147 (+ AC)] and Hb E [β26(B8)Glu→Lys] which displayed an asymptomatic erythrocytosis.

Keywords:

• Hb Tak
• High oxygen affinity hemoglobin
• Secondary erythrocytosis