Hb Suan‐Dok [α109(G16)Leu→Arg; CTG→CGG (α2)] Described in a Patient of African Ancestry

Abstract

A 58‐year‐old Black female from Curaçao (West Indies) was recently referred to our Laboratory for a persistent microcytic hypochromic anemia. An analysis 13 years earlier had shown no abnormal hemoglobin (Hb) fractions and a balanced β/α synthetic ratio. The hematological indices were again compatible with thalassemia and no abnormal fractions were observed on electrophoresis or high‐performance liquid chromatography (HPLC). None of the seven common α‐thalassemia (thal) deletion defects were present. Direct sequencing of the α2 gene revealed a CTG→CGG single base substitution at codon 109. This mutation was previously described in a Thai patient (Hb Suan‐Dok), inducing Hb H disease in association with a – –^SEA allele. In contrast with earlier reports we were unable to identify any native Hb fraction. The balanced β/α ratio indicated that α2‐Suan‐Dok is formed but does not form tetramer formation unless α‐thal is present.

• Abnormal hemoglobin (Hb)
• Thalassemia (thal)