Series of inherited forms of hemolytic anemia caused
by alterations in the red cell membrane, resulting in leakage of sodium and
potassium. After resaturation of normal permeability, red cell membrane
rigidity, morphology, water content, and cell cation return to normal. Low
potassium is dominant to high potassium.
Cryohydrocytosis; Overhydrated Hereditary Stomatocytosis.
Unknown. Approximately 1:10,000 kindreds in France and
the United Kingdom have hereditary xerocytosis. Familial pseudohyperkalemia
does not seem to occur in the United States.
Autosomal dominant. Mutation located on
chromosome 16, but the gene is not yet identified. Except for hereditary
xerocytosis, the red blood cell membrane of stomatocytoses is defective for
the stomatin protein (or “erythrocyte membrane protein 7.2b”).
The red blood cells have a membrane abnormality
with increased permeability to cations, with a greater efflux of potassium
than sodium. Consequently, these red cells lose potassium in excess of
the sodium gained, with a decrease in total cation content.
Laboratory findings include hemoglobinuria,
reticulocytosis, increased red cell hemolysis by shear stress, increased
mean corpuscular volume, and increased mean corpuscular hemoglobin
concentration. The visual aspect of red blood cells varies depending on the
variant: very stomatocytic for the rather common overhydrated hereditary
stomatocytosis, xerocytic for the rarer dehydrated hereditary
stomatocytosis, and no anemia in familial pseudohyperkalemia.
Patients generally have few symptoms but may have
exercise-induced episodes of fatigue, associated with jaundice, pallor, or
darkened urine. Splenomegaly and cholelithiasis may occur. Hemoglobin levels
are often normal or near-normal, despite clinical and laboratory evidence of
mild-to-moderate hemolysis (except for familial pseudohyperkalemia).
Blood transfusions are generally not required, and the benefit of splenectomy is
slight. Furthermore, if the spleen is removed, problems with excessive blood
clotting may arise later in life. Iron overload may develop later in life.
Check hemoglobin level and
Potential reduction in oxygen delivery
because of decreased levels of 2,3-diphosphoglycerate.
No known specific implications for
Hereditary Spherocytosis: Genetically transmitted hemolytic
anemia as a result of mutations in the spectrin gene in people of
circum-Mediterranean descent; autosomal dominant and recessive forms are
Hereditary Pyropoikilocytosis: Autosomal
dominant hemolytic medical condition in
which erythrocytes have a bizarre morphology similar to that seen in thermal
burns. It is probably the result of coinheritance of a mutation impairing spectrin
association (and causing hereditary elliptocytosis) and a second mutation
that results in quantitative spectrin deficiency.
Hereditary Xerocytosis: Characterized by red
cell membrane abnormality with increased permeability to cations causing a
greater efflux of potassium than sodium. Consequently these red cells
lose potassium in excess of sodium gained, with a decrease in total cation
content. Osmotically resistant xerocytes result. Clinically, the patient may
present with episodes of fatigue, jaundice, pallor, and darkened urine,
especially during intense physical activity. At the other end of the
spectrum from xerocytosis is hereditary stomatocytosis (or hydrocytosis), ...