Tetramer Information and Courses from MediaLab, Inc.
These are the MediaLab courses that cover Tetramer and links to relevant pages within the course.
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| Anemia in Alpha Thalassemia In thalassemia there is often an excess production or accumulation of globin chains produced by genes that are not effected by the thalassemia deletion. In alpha thalassemia this may be seen as gamma chain tetramers (hemoglobin Bart's) in the unborn child and as beta chain tetramers (hemoglobin H) in adults. Tetramer accumulation often leads to red blood cell damage and hemolytic anemia. | View Page |
| Chromosome 16 Alpha Thalassemia Intermedia When three loci of alpha chains are deleted (--/-) or inactive, only 70-90% of Hemoglobin A is made. The excess beta chains that remain unpaired form the tetramers of Hemoglobin H.(drawing modified from Harmening, 1999) | View Page |
| Wright's stained peripheral blood smear made from EDTA specimen.What RBC morphologies are present? | View Page |
| Summary The normal RBC count (4.84 x 1012/L) in this case, together with the decreased hemoglobin (8.4 g/dL) and MCV (59 fl) is an indicator of ineffective erythropoeisis that often points to thalassemia.The RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, and basophilic stippling. Schizocytes form by several mechanisms, one being the removal of RBC inclusions.This patient's elevated bilirubin correlates with her presentation of sclera icterus; her splenomegaly is consistent with increased RBC destruction.The Hb electrophoresis demonstrated a normal pattern, initially, but the unstable Hemoglobin H was revealed upon repeat electrophoresis with reduced incubation time. Hemoglobin H is the result of beta globin chain tetramer formation due to the insufficient supply of alpha globin chains in alpha thalassemia intermedia.People with Hemoglobin H disease (alpha thalassemia intermedia) usually have a normal life expectancy without treatment. However, hemolysis may lead to moderate anemia that may be treated with splenectomy. | View Page |
| Alpha Thalassemia Intermedia Anemia is moderate.RBC count is increased.Hb is moderately decreased.MCV is decreased. MCHC is decreased.RDW is increased.RBC morphology shows slight hypochromic microcytosis with codocytes, schizocytes, and basophilic stippling.Reticulocytes are moderately increased.Hb electrophoresis demonstrates abnormal patterns in both adults and neonates.Adults:HbA decreasedHbA2 decreasedHbF normal to decreasedHb H -2-40% (beta chain tetramers)Neonates: 10-40% Bart's (gamma chain tetramers)Hb H inclusions are frequently seen.Bone marrow demonstrates erythroid hyperplasia. | View Page |
| Alpha Thalassemia Minor Anemia is mild to absent.RBC count is increased.Hb is slightly decreased.MCV is decreased. MCHC is slightly decreased.RDW is normal to slightly increased.Red Blood Cell morphology shows slight hypochromic microcytosis.Reticulocytes are normal to slightly increased.Hb electrophoresis demonstrates a normal pattern in adults:Hb A - 97-98% Hb A2 - 1-2.5% Hb F - <1%. Neonates have 5-15% Bart's Hemoglobin (gamma chain tetramers).Hb H inclusions are rarely seen.Bone marrow demonstrates erythroid hyperplasia. | View Page |
| Silent Carrier Anemia is absent.RBC count is within normal limits.Hb is within normal limits.MCV is normal to slightly decrease.MCHC is normal to slightly decrease.RDW is within normal limits.Red Blood Cell morphology is normal.Reticulocytes are within normal limits.Hb electrophoresis demonstrates a normal pattern in adults:Hb A - 97-98%Hb A2 - 1-2.5% Hb F - < 1%. Neonates have 1-2% Bart's Hemoglobin (gamma chain tetramers).Hb H inclusions are rarely seen.Bone marrow is normal. | View Page |
| Brilliant Cresyl Blue stain Hemoglobin H, consisting of beta chain tetramers, is an unstable hemoglobin which forms precipitates just below the cell's membrane and can be observed when red blood cells are stained with Brilliant Cresyl Blue (BCB). | View Page |
| Anemia in Beta Thalassemia In thalassemia, there is often an excess production or accumulation of globin chains whose genes are not affected by the deletion.In beta thalassemia, this may be seen as an increase in gamma chain and delta chain production, leading to increased levels of hemoglobin F and A2 respectively.Excess alpha chains may also form tetramers which often lead to red cell membrane damage and decreased red cell deformability. This leads to a hemolytic anemia. Adding to the anemia is a decrease in the total amount of hemoglobin produced in spite of the erythroid hyperplasia of the bone marrow. | View Page |
| A normal hemoglobin molecule is comprised of the following: | View Page |
| The following polypeptide chains are found in normal adult hemoglobin A: | View Page |
| Hemoglobin H disease Hemoblobin H disease follows deletions of 3 of the 4 alpha globulin chains. Beta chains, unable to bind with insufficient numbers of alpha chains, form beta chain tetramers, or HbH.These beta chain tetramers appear as numerous dot size inclusions in erythrocyte cytoplasm, best seen in supravital brilliant cresyl blue stains (lower photograph).The most common molecular defect in alpha thalassemia is DELETION, not MUTATION; whereas, in beta thalassemia, the molecular defect is MUTATION.Leptocytes, as illustrated in the upper photograph,(lepto, derived from a Greek word meaning thin, fine, or slight), are characteristic of HbH disease. They have thinner cell membranes than the cells we recognize as target cells. They stain more lightly than normal erythrocytes and their centers are almost colorless.Subtle changes perhaps, but worth keeping in mind | View Page |