RESUMEN
Hereditary stomatocytosis is a rare congenital hemolytic anemia, named after mouth shaped or stomatocytic erythrocyte morphology. In this report, we present a case of a hereditary stomatocytosis in a 1 month old boy. During the initial identification process, we overlooked the morphology of the RBC in peripheral blood smear and tentatively diagnosed it to be a hereditary spherocytosis case. In order to study further, we isolated RBC membranes from the patient, separated membrane proteins by SDS polyacrylamide gel electrophoresis, and found that a protein band, band 7, was missing in the patient. We suggest that erythrocyte morphology as well as erythrocyte membrane protein analysis is an important criterion in the diagnosis of hereditary hemolytic anemia.