RBC Band 3 Protein Reduction in Hereditary Spherocytosis

Content Review: November 2021 Last Update: July 2022

Use to confirm a diagnosis of hereditary spherocytosis when hemolytic anemia and spherocytes are present.

Related Test

Functional testing of RBC sensitivity to osmotic stress

Hereditary spherocytosis is a genetic disorder that causes congenital hemolytic anemia through the production of structurally compromised red blood cells (RBCs). The severity of the disease varies widely; most cases are classified as moderate and present with symptoms such as anemia, jaundice, and splenomegaly. Depending on the level of severity, a diagnosis of hereditary spherocytosis can rule out other causes of hemolytic anemia. 

Disease Overview

Prevalence

1/2,000 in individuals of northern European descent 

Genetics

Genes

ANK1, EPB42, SLC4A1, SPTA1, SPTB

Inheritance

  • Autosomal dominant: 75% 
  • Autosomal recessive: 25% 

Penetrance

Variable

Structure/Function

  • Chromosomal location: 17q21.31
  • Provides structure for the red cell cytoskeleton

Test Interpretation

Sensitivity/Specificity

Clinical sensitivity: 93%

Analytical sensitivity/specificity: unknown

Results

Test Result Interpretation

Normal

Normal staining of band 3 protein with EMA does not suggest hereditary spherocytosis

Abnormala

Decreased staining of band 3 protein with EMA provides evidence for hereditary spherocytosis

Equivocal

Insufficient evidence to support or negate a diagnosis of hereditary spherocytosis

Unclear whether the level of band 3 protein staining is normal

aThree other rare disorders may be associated with a positive result for this test: congenital dyserythropoietic anemia type 2, Southeast Asian ovalocytosis, and hereditary pyropoikilocytosis.

EMA, eosin-5-maleimide

Limitations

Recent transfusion (within the last three months) may affect test results; correlation with clinical and other laboratory findings is strongly recommended.

References