50 Hereditary Stomatocytosis Syndromes

Michelle To and Valentin Villatoro

Overhydrated Hereditary Stomatocytosis

Condition results in cells with altered intracellular concentrations of sodium (Na+) and potassium (K+) ions. There is an increased permeability of K+ into the cell and increased permeability of Na+ out of the cell. This results in cells with increased volume (cells are overhydrated), a decreased surface-to-volume ratio, and decreased cytoplasm viscosity.1-3



Hereditary defect leading to alterations in the permeability of the red blood cell membrane.


Inheritance: 1-3

Autosomal dominant (Severe hemolysis may indicate a autosomal recessive inheritance)


Laboratory Results:1-3


MCV: Increased

MCHC: Decreased




Other Tests:

Osmotic Fragility: Increased

Dehydrated Hereditary Stomatocytosis (Hereditary Xerocytosis)

Defects lead to an increased movement of K+ out of the cell and results in the dehydration of cell. Unlike Stomatocytes, cells have an increased surface-to-volume ratio.2



Autosomal dominant


Laboratory Results:1-4


MCV: Increased

MCHC: Increased



Target cells



RBCs with Hb concentrated at the periphery of the cell

Other Tests:

Osmotic Fragility: Increased


1. Keohane EM. Intrinsic defects leading to increased erythrocyte destruction. In: Rodak’s hematology clinical applications and principles. 5th ed. St. Louis, Missouri: Saunders; 2015. p. 367–93.

2. Coetzer T, Zail S. Hereditary defects of the red cell membrane. 5th ed. Philadelphia: F.A. Davis Company; 2009. p. 176–95).

3. Da Costa L, Galimand J, Fenneteau O, Mohandas N. Hereditary spherocytosis, elliptocytosis, and other red cell membrane disorders. Blood Rev [Internet]. 2013[cited 2018 Jul 24];27(4):167–78. Available from: http://www.sciencedirect.com/science/article/pii/S0268960X13000192

4. Andolfo I, Russo R, Gambale A, Iolascon A. New insights on hereditary erythrocyte membrane defects. Haematologica [Internet]. 2016 Nov 22 [cited 2018 Jun 26];101(11):1284–94. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5394881/


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