Hemoglobin Evans Associated with HBA1 Mutation: First Report from Rosario, Argentina.

Hemoglobin Evans is a rare, unstable α-chain variant resulting from a valine-to-methionine substitution at codon 62 (E11) of the α-globin gene, previously reported only in HBA2. We describe the first documented case involving the HBA1 gene (HBA1:c.187G > A), identified in a 3-year-old boy who was evaluated for persistent anemia. Laboratory findings revealed hemolytic anemia with low haptoglobin, a negative Coombs test, anisopoikilocytosis, basophilic stippling, and Heinz bodies. The isopropanol instability test was positive in the patient, his father, and his sister, while molecular analysis confirmed heterozygosity for the HBA1:c.187G > A variant in all three family members. This substitution, located in the heme crevice, likely disrupts heme binding and reduces hemoglobin stability, leading to hemolysis. The clinical phenotype was consistent with mild chronic hemolytic anemia, potentially related to the lower transcriptional activity of HBA1 compared with HBA2. This report expands the molecular spectrum of unstable hemoglobins and underscores the importance of α-globin gene analysis in the evaluation of unexplained hemolytic anemia.