Disorders Of Red Cell Membrane Flashcards
Weight percentage of red cell membrane
1%
Role of red cell membrane
Maintain RBC integrity, flexibility, durability, tensile strength ,
Red cell membrane components and function
Lipid bilayer (phospholipids, cholesterol -> permeability
Integral proteins
Membrane skeleton -> structural integrity
Major component of RCM
Lipids - 50-60%
Types of lipids in RCM
Phosphatidylcholine Phosphatidylethanolamine Phosphatidylserine Phosphatidylinositol Sphingomyelin Cholesterol
Cholesterol function in RCM
Control membrane fluidity
Integral membrane proteins
Glycophorins
Rh proteins
Kidd glycoproteins
Duffy glycoproteins
Lutheran glycoproteins
Peripheral membrane proteins
Spectrin Actin Ankaryn Protein 4.1 Protein 4.2 Protein p55, adducin, dermatitis, tropomyosin
Spectrin, actin and ankaryn functionsp
Maintain cellular shape
regulates natural mobility of integral membrane proteins
structural support for the lipid bilayer
Abnormality of this protein is the most common cause of typical hereditary spherocytosis
Ankaryn
Protein 4.1 role
Link Spectrin actin membrane to lipid bilayer
Protein 4.2 role
Stabilize Spectrin actin Ankaryn association with band 3
This type of proteins is responsible for maintenance of the structural integrity of the cell as well as the high tensile strength of the RCM
Horizontal proteins
What is the function of vertical Interactions of proteins
Stabilizes lipid bilayer
Most common disorders in the red cell membrane Hereditary anemia
Hereditary spherocytosis
Hereditary Elliptocytosis
Hereditary pyropoikilocytosis
What is hereditary spherocytosis
Disorders characterized by spherical red blood cell with increased osmotic fragility
Most common hereditary anemia in people of northern European descent
Hereditary spherocytosis
Main causes of hereditary spherocytosis ytosis
Deficiency of ankaryn spectrin and proteins 4.2
Which are involved in vertical interactions between membrane skeleton and lipid bilayer
Sodium potassium and water content in hereditary spherocytosis
Potassium and water are reduced
sodium is increased
What happens to read cell in the spring when there is hereditary spherocytosis
Red cells cannot deformed themselves to go through the splenic microcirculation so destruction of RBC sites in the spleen especially in acidic pH and low glucose levels
Clinical features of hereditary spherocytosis
Slight Anemia Hb does not go below 7.5 g/dl Jaundice splenomegaly Visible in multiple members of one family gallstone leg ulcers aplastic crisis especially in parvovirus
Laboratory findings of hereditary Spherocytosis
Anemia bloods film Multiple Spherocytes no central pallor reduced diameter MCHC increased Osmotic fragility increased Mean cell fragility over 0.45 reticulocyte count 5 to 20% negative coomb tests( so not inflammatory in origin )
Treatment of Hereditary spherocytosis
Folic acid
splenectomy if severe
What is Hereditary elliotocytosis
Similar to HS but elliptocytes instead
Who is first patient of HE
Medical students in dresbach
Incidence of HE
1 in 2000 or 4000 individuals
Maine population affected by hE
African and Mediterranean
Is there resistance to malaria in HE
Yes to some extent
Are most people are symptomatic in HE
Yes
Is HE autosomal dominant or recessive
Dominance in most patients
Is HE milder than HS
Yes requires the next to me on the rarely
Is HE due to vertical or horizontal to interactions defect
Horizontal
Why is HE mostly diagnosed incidentally
Because it’s mostly asymptomatic
What are other examples of hereditary red cell membrane disorders
Hereditary stomatacytosis
Hereditary Pyropoilikocytosis
South east Asian ovalocytosis
