Hereditary spherocytosis - Genetic diseases Membrane Blood Cells RedDefinition of Hereditary spherocytosis
Hereditary spherocytosis (HS): A genetic disease of the membranes (membrane) of red blood cells that is clinically characterized by anemia, jaundice (jaundice) and splenomegaly (enlarged spleen).
In HS the red cells are smaller, more rounded, and more easily damaged than normal. These red cells have a spherical shape than double concave plate-shaped (biconcave-disk shape) of red cells are normal. The cells of this rotund red (spherocytes) are osmotically fragile and less flexible than normal red cells and tend to get in narrow blood vessels, especially in the spleen, and there they break up (hemolyze) leading to hemolytic anemia .
Blockage of the spleen with red cells almost invariably causes an enlarged spleen (splenomegaly). Solving the red cells releases hemoglobin and heme part gives rise to bilirubin, the pigment of jaundice. Excess bilirubin leads to the formation of gallstones (gallstones), even in childhood. Often there is also an overload of iron (iron) caused by excessive destruction of red cells are rich in iron.
Hereditary spherocytosis is most common in people of northern European ancestry. It often arises in childhood or early childhood, causing anemia and jaundice. Bone marrow has to work extra hard to make more red cells. So, if in the course of a viral illness commonly, the bone marrow stops making red cells, anemia can quickly become severe (extremely large). This is termed an aplastic crisis (aplastic crisis).
Laboratory studies show evidence not only of many spherocytes but also increased amounts of reticulocytes (red blood cells of the young), hyperbilirubinemia (blood levels are increased from that makes the yellow pigment bilirubin due to breakdown of red cells ) and osmotic fragility of red cells increased.
HS is caused by a deficiency of a protein called ankyrin. Ankyrins are cell membrane proteins (thought to interconnect the integral proteins with the spectrin-based membrane skeleton). Ankyrin of red blood cells (erythrocytic ankyrin) is called ankyrin-R or ankyrin-1. It is represented by the symbol ANK1.
HS genes are to ANK1 been mapped on chromosome 8 and, in particular, on chromosome band 8p11.2. HS is inherited as a dominant trait, so if someone with a HS reproduction, their children (no matter if he was a son or daughter) have a 50:50 chance of getting HS.
Treatment of hereditary spherocytosis is to remove the spleen (splenectomy). Although red cell damage persists, the breakup of the red cells (hemolysis) ceases. Splenectomy, however, is a hazard / risk in young children. Young people without a spleen are at increased risk for overwhelming sepsis (bloodstream infection), particularly with the pneumococcus bacteria. Splenectomy is therefore usually postponed if possible until the age of 3 years. Before having a splenectomy, anyone with HS should get pneumococcal vaccine. People with HS (or another cause of brisk ongoing hemolysis) should take supplemental folic acid (folic acid).
The prognosis (forecast / outlook) after splenectomy is for a normal life and a normal life expectancy.
HS is also known as hemolytic jaundice since birth (congenital hemolytic jaundice), severe atypical spherocytosis (severe atypical spherocytosis), spherocytosis type II, ankyrin deficiency, erythrocyte ankyrin deficiency, ankyrin-R deficiency, and lack ankyrin1.
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