Question 1

Which red cell inclusion is characteristic of G6PD deficiency?

Accepted Answer

Heinz bodies are characteristic of G6PD deficiency. They are denatured hemoglobin aggregates that form when red blood cells are exposed to oxidative stress. G6PD deficiency leads to reduced antioxidant capacity in red blood cells, making them more susceptible to oxidative damage and the formation of Heinz bodies. Cabot rings are remnants of the mitotic spindle and are not specific to any disease. Howell-Jolly bodies are nuclear remnants that are normally removed by the spleen, but can be seen in conditions where the spleen is removed or non-functional. Pappenheimer bodies are iron-containing granules seen in disorders of iron metabolism. Siderotic granules are also iron-containing granules seen in conditions like sideroblastic anemia.

Question 2

Which of the following types of G6PD enzyme is the most common form in all populations and exists in 99% of whites in the United States?

Accepted Answer

Gd B is the most common form of G6PD enzyme in all populations, including 99% of whites in the United States. It represents the normal, non-deficient form of the enzyme.

Question 3

Which of the following is a screening test for G6PD deficiency?

Accepted Answer

All of the options listed (Heinz body stain, Methemoglobin reduction test, and Ascorbate-cyanide test) are used as screening tests for Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency. These tests help identify red blood cells that are deficient in G6PD, which is crucial for protecting the cell from oxidative damage.

Question 4

Which of the following is characteristic of PK deficiency?

Accepted Answer

All of the listed characteristics are commonly found in PK deficiency. The severity of hemolytic anemia varies, varying degrees of polychromasia and poikilocytosis may be present on the peripheral smear and nucleated red cells may be seen, clinical manifestations like splenomegaly and cholelithiasis are common, and onset may occur during infancy, early childhood or even in adulthood, especially in individuals with mild cases.

Question 5

The diagnosis of G6PD deficiency in a black man during acute hemolysis may be difficult to detect in a screening test due to:

Accepted Answer

During acute hemolysis, the increased number of younger red cells (reticulocytes) that have normal levels of G6PD and a lack of older G6PD-deficient red cells due to hemolysis can make it difficult to detect G6PD deficiency in a screening test. This is because screening tests rely on the detection of G6PD-deficient red cells, and during acute hemolysis these may not be present or may be present in very low numbers. Drug interference, the presence of too many G6PD-deficient red cells, or the presence of white blood cells or platelets are not likely to affect the screening test for G6PD deficiency.

Question 6

A laboratory result that would suggest a PK deficiency on a 20-year-old patient is/are?

Accepted Answer

PK (Pyruvate Kinase) deficiency is a rare cause of chronic nonspherocytic hemolytic anemia. The characteristics of PK deficiency include a negative DAT (direct antiglobulin test), indicating that the hemolysis is not immune-mediated; an abnormal autohemolysis test that is not corrected by the addition of glucose, reflecting the underlying metabolic defect in the red blood cells; and a normal osmotic fragility test in freshly drawn blood, as the hemolysis is not due to membrane fragility but rather to an enzymatic defect in the glycolytic pathway.

Question 7

Which of the following most often represents the pattern of inheritance for pyruvate kinase deficiency?

Accepted Answer

Pyruvate kinase deficiency is typically inherited in an autosomal recessive pattern, meaning two copies of the mutated gene are necessary for the condition to occur.

Question 8

Which of the following represents the pattern of inheritance of G6PD deficiency?

Accepted Answer

G6PD deficiency is inherited in an X-linked pattern, meaning the gene responsible for this condition is located on the X chromosome.

Question 9

Hemolysis induced by drugs is a clinical feature commonly seen in which G6PD deficiency?

Accepted Answer

Hemolysis induced by drugs is commonly seen in G6PD deficiency type Med. Gd A- may cause hemolysis in response to certain triggers, but drug-induced hemolysis is not commonly seen in this type.

Question 10

Hemolysis induced by infection is a clinical feature commonly seen in which G6PD deficiency?

Accepted Answer

G6PD deficiency variants Gd A- and Gd Med can both lead to hemolysis induced by infection. This is because individuals with these variants have reduced activity of the glucose-6-phosphate dehydrogenase enzyme, making their red blood cells more vulnerable to oxidative damage, which can be triggered by infections.

Question 11

What is the major clinical feature of a patient with methemoglobinemia?

Accepted Answer

Cyanosis is the major clinical feature of methemoglobinemia, as the hemoglobin molecule is unable to release oxygen to the tissues in its oxidized form. This results in a bluish discoloration of the skin, mucous membranes, and nail beds. Reticulocytosis, splenomegaly, and pallor are not usually associated with methemoglobinemia. Favism is a genetic condition that results in hemolysis of red blood cells after ingesting fava beans, and is not related to methemoglobinemia.

Question 12

Which variant of the G6PD enzyme is commonly found in the Chinese and in people of Southeast Asia?

Accepted Answer

Gd Canton is a variant of the G6PD enzyme that is commonly found in the Chinese population and in people of Southeast Asia. This variant is associated with G6PD deficiency, a genetic condition that can lead to hemolytic anemia under certain conditions.

Question 13

Which G6PD enzyme commonly found in Africans has normal activity but differs from that found in whites by a single amino acid substitution that alters its electrophoretic mobility?

Accepted Answer

Gd A+ is the variant of G6PD enzyme commonly found in Africans that has normal activity but differs from that found in whites by a single amino acid substitution, which alters its electrophoretic mobility.

Question 14

Which of the following represents the second most frequently encountered enzyme deficiency that causes a hemolytic anemia?

Accepted Answer

Pyruvate kinase deficiency is the second most common cause of hemolytic anemia after glucose-6-phosphate dehydrogenase deficiency. Hexokinase and lactic dehydrogenase deficiencies are rare and not typically associated with hemolytic anemia.

Question 15

Patients with which type of G6PD deficiency present with chronic hemolysis?

Accepted Answer

Patients with G6PD deficiency typically present with episodic rather than chronic hemolysis, often triggered by infections, certain foods, or medications. Neither Gd A- nor Gd Med variants are associated with chronic hemolysis.

Question 16

The presence of Heinz bodies is related to which enzyme deficiency?

Accepted Answer

Heinz bodies are associated with deficiencies in both glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase, which are options A and C, respectively.

Question 17

Which of the following can cause methemoglobinemia?

Accepted Answer

All of the choices can cause methemoglobinemia. Hereditary enzyme deficiency of NADH-methemoglobin reductase affects the ability of the enzyme to convert methemoglobin back to hemoglobin. Exposure to strong oxidizing drugs or toxic substances can cause the formation of methemoglobin directly. Hemoglobin M disease is a rare genetic disorder where hemoglobin is structurally abnormal and cannot bind oxygen effectively, leading to the accumulation of methemoglobin.

Question 18

Which of the following forms of G6PD enzymes is the product of a mutant gene located on the X chromosome resulting in a G6PD deficiency that occurs in 10-15% of American blacks?

Accepted Answer

Gd A- is the form of G6PD enzyme that results from a mutant gene located on the X chromosome and causes G6PD deficiency in 10-15% of American blacks. The other forms listed (Gd A+, Gd Med, Gd B, Gd Canton) are all normal or variant forms of the G6PD enzyme but are not associated with this particular mutation and deficiency.

Question 19

Favism is a clinical feature that occasionally occurs in which G6PD deficiency?

Accepted Answer

Favism is a clinical feature that occasionally occurs in individuals with G6PD Mediterranean (Gd Med) variant, due to their severely reduced G6PD enzyme activity, leading to the destruction of red blood cells under exposure to certain triggers, such as fava beans. G6PD A- individuals may also experience hemolysis under certain conditions, but not necessarily due to fava beans, while G6PD deficient individuals with other variants are usually asymptomatic.

Question 20

Occasionally transfusions may be required in which type of G6PD deficiency?

Accepted Answer

Transfusions may be required in severe cases of G6PD deficiency such as in Gd Med, but not typically in Gd A-.

Quiz 10: Hemolytic Anemias: Intracorpuscular Defects: II Hereditary Enzyme Deficiencies