Hemoglobin Ottawa (Hba2:C.46g > C) And Beta(+) Thalassemia (Hbb:C.-138c > T) Detected In An Indian Male By Capillary Zone Electrophoresis

Hemoglobin (Hb) Ottawa [alpha 15(A13)Gly>Arg], also known as Hb Siam, results from GGT>CGT mutation in codon 15 of either HBA1 or HBA2. Hb Ottawa carriers typically have normal hematology but when the variant is coinherited with either alpha or beta thalassemia, microcytic red cell indices were observed. The percentage of variant detected using routine methodology was variable (14-33%), with a higher percentage found when co-inherited with an abnormal alpha-globin genotype. The case presented here involved an Indian male with microcytic red cell indices, who was heterozygous for Hb Ottawa (HBA2: c.46G>C) and beta(+) thalassemia (HBB:c.-138C>T). This case represents the first reported finding of Hb Ottawa in the Indian population, as well as the first time capillary zone electrophoresis (CZE) has been used to identify the variant. The abnormal red cell indices were attributed to co-inheritance of beta(+) thalassemia mutation (HBB:c.-138C>T), which alters binding of transcriptional factors to the HBB promoter and reduces transcription from the allele. The mild beta(+) thalassemia mutation has commonly been found in the Indian population.