[1] The two varieties of stomatocytosis classified with respect to cellular hydration status are overhydrated (hydrocytosis) and dehydrated (xerocytosis).

[2]: 225–226  Hereditary xerocytosis is characterized by autosomal dominant mutations in PIEZO1, which encodes a cation channel whose mechanosensitive properties enable erythrocytes to deform as they pass through narrow capillaries by decreasing their intracellular volume.

Overhydrated hereditary stomatocytosis is frequently linked to mutations in genes that encode components of the band 3 complex, such as RHAG.

[4] It is the altered band 3 protein complex which mediates the cation leaks that are characteristic of hydrocytotic hereditary stomatocytosis.

These include cases of phytosterolemia nonleaky stomatocytosis, a disorder of lipid metabolism associated with mutations in ABCG5 and/or ABCG8, which encode sterol transporters.

[1] The resulting abnormal sterol composition of erythrocyte cell membranes causes them to appear as deformed stomatocytes on peripheral blood smear.