Question 1

Which of the following may be found on the hemoglobin electrophoretic pattern for sickle cell anemia?

Accepted Answer

All of the options listed can be found in the hemoglobin electrophoretic pattern for sickle cell anemia, so E is the correct answer. A) No HbA (0%) - This is expected in individuals with sickle cell anemia as they do not produce normal hemoglobin A. B) 80-100% HbS - This is the abnormal hemoglobin that causes sickle cell anemia. C) 1-20% HbF - This is fetal hemoglobin and is higher in individuals with sickle cell anemia as it can help reduce sickling. D) 2-4% HbA₂ - This is a specific variant of sickle cell hemoglobin that can be found in some individuals with sickle cell anemia, but it is not always present.

Question 2

Which of the following is characteristic of the peripheral blood smear in hemoglobin SC disease?

Accepted Answer

All of the listed features are characteristic of hemoglobin SC disease on peripheral blood smear. Target cells, folded red cells, and occasional glove-shaped intracellular are all hallmarks of sickle cell disease, and normocytic normochromic anemia is a common finding in hemoglobin SC disease specifically.

Question 3

Which of the following is characteristic of HbC disease?

Accepted Answer

HbC disease is an inherited blood disorder caused by a mutation in the HBB gene. It results in the production of abnormal hemoglobin C, which can cause a mild chronic hemolytic anemia. Splenomegaly may also occur as the spleen's job is to remove damaged red blood cells from the circulation. Normocytic, normochromic anemia with numerous target cells (50-90%) and occasional folded cells is a typical finding on a blood smear. Additionally, Hemoglobin C ("bar of gold") crystals may be present on the blood smear of splenectomized patients. Therefore, option E "All of the above" is the correct answer.

Question 4

In hemoglobin SC disease what is the percentage of HbS and HbC found on the hemoglobin electrophoresis at alkaline pH?

Accepted Answer

In hemoglobin SC disease, the percentage of HbS and HbC found on the hemoglobin electrophoresis at alkaline pH is approximately 50:50. This is because hemoglobin SC disease is a genetic condition where an individual inherits one copy of the HbS gene from one parent and one copy of the HbC gene from the other parent. As a result, the individual produces hemoglobin molecules that are composed of roughly equal amounts of HbS and HbC.

Question 5

Which of the following is characteristic of the hemoglobin electrophoresis at alkaline pH for hemoglobin SC disease?

Accepted Answer

Hemoglobin SC disease is characterized by the presence of both hemoglobin S (HbS) and hemoglobin C (HbC) in nearly equal amounts, typically around 50% each. Additionally, the level of fetal hemoglobin (HbF) is usually less than 2% in individuals with this condition. Therefore, all of the listed options (A, B, C) are characteristic of hemoglobin SC disease when analyzed by hemoglobin electrophoresis at alkaline pH.

Question 6

Which of the following hemoglobin(s) is/are present in hemoglobin SC disease?

Accepted Answer

Hemoglobin SC disease is a genetic disorder characterized by the presence of both HbS and HbC in the blood. HbA is not typically present in individuals with this disease. Therefore, the correct answer is A and C, as only HbS and HbC are present in hemoglobin SC disease.

Question 7

Which of the following abnormal hemoglobins will have a positive tube solubility test?

Accepted Answer

The tube solubility test is used to identify hemoglobins that have decreased solubility, indicating the presence of abnormal hemoglobin variants. HbS, which is the abnormal hemoglobin associated with sickle cell trait/disease, has decreased solubility and will cause formation of microcrystals upon addition of sodium dithionite solution in the tube solubility test. HbD and HbG do not typically have decreased solubility and will not cause microcrystal formation in the tube solubility test.

Question 8

Which of the following cannot be used as a screening test for hemoglobin S in newborns?

Accepted Answer

Tube solubility tests and Sodium metabisulfite sickle prep are not specific or sensitive enough for use as screening tests in newborns, whereas hemoglobin electrophoresis can accurately identify hemoglobin S among other hemoglobin variants.

Question 9

Which amino acid will differentiate hemoglobin C disease from normal HbA?

Accepted Answer

Hemoglobin C disease is characterized by a mutation in the beta-globin gene where the amino acid glutamic acid is replaced by lysine at the sixth position.

Question 10

Which abnormal hemoglobin migrates in the same position as HbA₂ on hemoglobin electrophoresis at alkaline pH?

Accepted Answer

HbC migrates in the same position as HbA₂ on hemoglobin electrophoresis at alkaline pH. HbF, HbS, HbG, and HbD have different migration patterns on electrophoresis.

Question 11

Which of the following is characteristic of hemoglobin SC disease?

Accepted Answer

Hemoglobin SC disease is a type of sickle cell disease that results from inheriting one sickle cell gene ('S') and one gene for hemoglobin C ('C'). Patients with hemoglobin SC disease often have milder anemia compared to those with sickle cell anemia (SS disease), but they can still experience significant complications. These complications include a greater incidence of retinal hemorrhages due to blood vessel abnormalities in the eye, renal papillary necrosis as a result of sickling in the kidneys, and necrosis of the femoral head due to impaired blood flow to the bone. Therefore, all the listed options are characteristic of hemoglobin SC disease.

Question 12

Hemoglobin C disease is found almost exclusively in which population?

Accepted Answer

Hemoglobin C disease is predominantly found in individuals of African descent. It is estimated that up to 2% of African Americans carry the Hemoglobin C gene. It is not commonly found in populations of Caucasian, Asian or Oriental descent.

Question 13

Most hemoglobin variant traits without coexisting conditions of iron-deficiency anemia or thalassemia have approximately what percentage ratio of normal to abnormal hemoglobin?

Accepted Answer

The answer of Most hemoglobin variant traits without coexisting conditions...

Question 14

Which of the following may be found on the hemoglobin electrophoresis at alkaline pH?

Accepted Answer

Option A is possible as HbC migrates to a slower position than HbA at alkaline pH, and HbA₂ is a rare hemoglobin variant that migrates at a similar position to HbC. Option B is possible as HbA does not migrate at alkaline pH, thus it will not be present on the electrophoresis. Option C is possible as HbF migrates faster than HbA at alkaline pH and may be present in small amounts. Therefore, all options are possible and the best choice is D.

Question 15

What is the frequency of hemoglobin C disease in American blacks in the United States?

Accepted Answer

The answer of What is the frequency of hemoglobin C...

Question 16

Which of the following represents the only significant finding on the peripheral smear in hemoglobin C trait?

Accepted Answer

Targeting is the only significant finding on the peripheral smear in hemoglobin C trait. Hemoglobin C crystals, nucleated red cells, and significant anisocytosis and poikilocytosis are not typically seen on peripheral smears in hemoglobin C trait.

Question 17

Which of the following hematological results will suggest an individual with sickle cell trait?

Accepted Answer

Individuals with sickle cell trait typically have a normal peripheral blood smear with the exception of target cells, positive solubility screening tests, and hemoglobin electrophoresis that demonstrates hemoglobin A, hemoglobin S, and sometimes slightly elevated hemoglobin A2 and F. Sickle cells are not usually present on the peripheral smear in sickle cell trait, distinguishing it from sickle cell disease.

Question 18

Which of the following hemoglobins migrates to the same position as HbS on hemoglobin electrophoresis at alkaline pH?

Accepted Answer

HbC has a glutamic acid to lysine substitution at position 6 on the beta-globin chain, which causes it to migrate to the same position as HbS on hemoglobin electrophoresis at alkaline pH. HbD and HbG have different amino acid substitutions and therefore migrate to different positions. A and C are incorrect answers.

Question 19

Hemoglobin D migrates in the position of what other hemoglobin on hemoglobin electrophoresis at alkaline pH?

Accepted Answer

Hemoglobin D migrates in the same position as HbS (Sickle Cell Hemoglobin) on hemoglobin electrophoresis at alkaline pH.

Question 20

What percentage of American blacks carry the hemoglobin C trait?

Accepted Answer

The hemoglobin C trait is most commonly found in people of African descent. Studies show that 2-3% of American blacks carry the hemoglobin C trait in their blood. This trait can cause a mild anemia and does not typically cause serious health problems.

Quiz 11: Hemolytic Anemias: Intracorpuscular Defects: III the Hemoglobinopathies