Hereditary Spherocytosis is one type of hemolytic anemia. We are going to discuss on it in detail. We gonna cover on pathogenesis, clinical manifestation and few other things that might pass through my head along the way.
First of all, this is a genetic disease, which form the name itself implies it can be inherited. Ok, before we go any further, let us do some recap o Histology of erythrocytes.
Erythrocyte is biconcave in shape. Why? Because it has a complex cytoskeleton architecture that holds its plasma membrane into place.
1) Vertical filaments (anchor the plasma membrane)
2) Horizontal filaments
3) Protein links between both vertical and horizontal filaments
+15 monomeres of actin
So, what turns wrong in spherocytosis?
Spherocytocis is an autosomal genetic disorder, in which:-
1) 85% autosomal dominant trait
+ Means the gene only needs a single allele (heterozygous) to express its abnormality
2) 25% autosomal recessive trait
+It requires two similar alleles (homozygous) to express its abnormality
Often, this kind of disorder leads to more severe spherocytosis
This abnormal genes somehow affect :-
1) Band 3
In people with hereditary spherocytosis, these filaments are found absent and due to that, RBCs couldn’t maintain its original morphology of biconcavity. As the name implies, spherocytosis red cells appear spherical in shape thus loosing its distinctive central pallor area in blood smear.
It becomes spherical due to loss of membrane stability – some membrane with few cytoplasms are released. RBC which spgerical in shape is rigid and couldn’t pass through splenic sinusoid thus making it highly susceptible to be phagocytosed by splenic macrophage.
It has a high chance of getting splenomegaly in patient with spherocytosis (mechanism is the same to that of general pathogenesis of hemolytic anemias we already discussed before). There is profound jaundice in spherocytosis. Due to the increased hemolysis, there will be compensatory mechanism of erythropoeisis which will eventually lead to erythroid (red marrow) hyperplasia and increase presence of reticulocytes at peripheral blood flow (reticulocytosis)
Due to its distinctive clinical manifestation to the spleen, it is found beneficial to do splenectomy (removal of the spleen) for this patient even though spherocytes still persist. Until now, there is still no profound treatment proposed for spherocytosis rather than splenectomy.
Morphology and Clinical Manifestations
1) Lack of central pallor region of RBCs on the blood smear
2) Increased presence of reticulocytes at the peripheral blood (reticulocytosis)
3) Splenomegaly – 500gm to 1000gm
4) Congestion in the cord of Bilroth of the spleen
5) Increased number of splenic macrophages
Next we will discuss on Sickle Cell Anemia.
Until then, thank you!! =)