Among these cases with enzyme defects, in four patients from three families a coinheritance of hereditary stomatocytosis was also suspected due to the presence of stomatocytes at peripheral blood smear and left-shifted Osmoscan curve; only in two of them (5-1 and 5-2) in addition to G6PD deficiency we found a mutation in PIEZO1 gene causing hereditary stomatocytosis. This evidence concerns the gene PIEZO1 and G6PD deficiency.