Dehydrated hereditary stomatocytosis (DHS), also known as hereditary xerocytosis, is an autosomal dominant congenital disorder associated with erythrocyte dehydration clinically manifest as mild to moderate hemolytic anemia. Affected red cells are characterized by a nonspecific cation leak of the red cell membrane, reflected in elevated sodium content, decreased potassium content, elevated mean corpuscular hemoglobin concentration (MCHC) and mean corpuscular volume (MCV), and decreased osmotic fragility. The definitive diagnosis of DHS is made by osmotic gradient ektacytometry, which shows a leftward shift of the bell-shaped curve. In many patients, heterozygous mutations in the mechanosensitive cation channel gene PIEZO1 have been identified. Mutations in the Gardos channel, encoded by the KCNN4 gene, have also been identified.
