Stomatocytosis of Standard Schnauzers is not associated with stomatin deficiency

Stomatocytosis resembles human overhydrated hereditary stomatocytosis (OHSt), a disease characterised by a reduced or absent stomatin expression. The objective of this report was to investigate the expression level of stomatin in erythrocytes from Standard Schnauzers with stomatocytosis. Routine haematology, intraerythrocytic Na+/K+ concentration and stomatin expression were evaluated in blood from twelve Standard Schnauzers and from three controls. SDS–PAGE and Western blotting on isolated integral membrane proteins were used to investigate stomatin expression. Circulating stomatocytes, macrocytosis, anisocytosis, increased erythrocyte fragility and high intracellular sodium and potassium concentrations were found in 10/12 dogs from the same breeding line although stomatin levels were similar to those of controls. In spite of the clinico-pathological similarities between human and canine stomatocytosis, erythrocytes from affected dogs do not lack stomatin and the expression level of this protein cannot therefore be used to diagnose hereditary stomatocytosis in Standard Schnauzers.