First Case of Compound Heterozygotes for Hb G-Georgia (HBA2:c.287C>T)/α0-thalassemia --SEA Deletion Found in Northern Thailand

Hemoglobin (Hb) G-Georgia is an α-globin variant caused by a mutation at codon 95 which substitutes the amino acid proline with a leucine. Heterozygosity for Hb G-Georgia may cause mild anemia, even though it is often asymptomatic. The Hb G-Georgia homozygosity or compound heterozygosity with other thalassemias can result microcytic hypochromic anemia with mild splenomegaly. We report the first case of compound heterozygosity for Hb G-Georgia/α0-thalassemia --SEA deletion (αGGα/--SEA) in a 62-year-old Thai woman living in Chiang Mai, northern Thailand. She presented with clinical symptoms of fatigue and dyspnea. Her hematological features revealed microcytic hypochromic anemia, but she had never received a blood transfusion. Hb analysis using capillary electrophoresis (CE) showed the peak of Hb G-Georgia (50.8%) in zone 7 (HbF zone). High-performance-liquid-chromatography (HPLC) showed coelution with HbA at the retention time of 2.36 minutes, and premier-resolution HPLC (PR-HPLC) detected 52.2% Hb G-Georgia but without clear separation from HbA. Next-generation sequencing confirmed the HBA2:c.287C>T mutation, and a single-tube multiplex real-time PCR with EvaGreen and high-resolution melting (HRM) analysis detected α0-thalassemia --SEA type deletion. Therefore, understanding genetic interactions between this α-globin variant and α0-thalassemia can help a better disease management and appropriate genetic counseling.