Disorders of erythrocyte volume homeostasis

Abstract

Inherited disorders of erythrocyte volume homeostasis are a heterogeneous group of rare disorders with phenotypes ranging from dehydrated to overhydrated erythrocytes. Clinical, laboratory, physiologic, and genetic heterogeneities characterize this group of disorders. A series of recent reports have provided novel insights into our understanding of the genetic bases underlying some of these disorders of red cell volume regulation. This report reviews this progress in understanding determinants that influence erythrocyte hydration and how they have yielded a better understanding of the pathways that influence cellular water and solute homeostasis.

Keywords: Band 3; Erythrocyte; GLUT1; PIEZO1; RhAG; stomatocytosis; volume homeostasis; xerocytosis.

Figure 1

Peripheral blood smears from patients with abnormalities of erythrocyte volume homeostasis. (A) A Wright-stained peripheral blood smear from a patient with hereditary hydrocytosis is shown. Numerous stomatocytes (arrow), erythrocytes with a central mouth-like ‘stoma’ are seen. (B) A Wright-stained peripheral blood smear from a patient with hereditary xerocytosis due to a PIEZO1 mutation showing rare stomatocytes, occasional dessicytes–dense, abnormal erythrocyte forms where hemoglobin appears puddled at the periphery, and rare target cells (arrow).