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Haematology > L.7 Haemoglobinopathies > Flashcards

L.7 Haemoglobinopathies Flashcards

1
Q

What mutation is associated with Hb C?

A

β6 Glu>Lys

Hb C is characterized by a mutation that leads to mild haemolytic anaemia.

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2
Q

What percentage of patients with SCD have Hb S/C?

A

Accounts for 20-50%

Hb S/C is associated with less severe vaso-occlusive complications.

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3
Q

What is the mutation in Hb E?

A

β26 Glu>Lys

Hb E is probably the most common Hb variant globally and homozygotes exhibit mild anaemia.

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4
Q

What is the mutation associated with Hb D?

A

β121 Glu>Gln

Hb D is mostly asymptomatic.

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5
Q

True or False: Hb E homozygotes experience severe anaemia.

A

False

Hb E homozygotes typically have mild anaemia.

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6
Q

Fill in the blank: Hb C is characterized by a mutation from Glu to _____ at position 6.

A

Lys

This mutation leads to mild haemolytic anaemia.

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7
Q

Fill in the blank: Hb S/C accounts for _____ percent of patients with SCD.

A

20-50

It is associated with less severe vaso-occlusive complications.

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8
Q

What is the clinical significance of Hb D?

A

Mostly asymptomatic

Hb D does not typically cause health issues.

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9
Q

What is the typical hemoglobin level (Hb) in alpha-thalassaemias?

A

Hb ↓(70-100 g/l)

A decreased hemoglobin level is a key indicator in alpha-thalassaemias.

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10
Q

What are the changes observed in MCV and MCH in alpha-thalassaemias?

A

MCV↓ MCH ↓

Mean Corpuscular Volume (MCV) and Mean Corpuscular Hemoglobin (MCH) are both decreased.

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11
Q

What are the main findings in a blood film for alpha-thalassaemias?

A
  • Hypochromic Microcytes
  • Target Cells
  • Anisopoiklocytosis
  • Polychromasia
  • NRBC
  • Pappenheimer Bodies
  • Basophillic Stippling

These findings indicate various abnormalities in red blood cells.

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12
Q

What is the significance of reticulocytes in the diagnosis of alpha-thalassaemias?

A

Reticulocytes

Elevated reticulocyte counts can indicate increased red blood cell production.

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13
Q

What laboratory results are typically elevated in alpha-thalassaemias?

A
  • LDH ↑
  • Bilirubin ↑

Elevated levels of lactate dehydrogenase (LDH) and bilirubin are often observed.

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14
Q

What happens to haptoglobin levels in alpha-thalassaemias?

A

Haptoglobin ↓

Decreased haptoglobin levels can indicate hemolysis.

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15
Q

What is the appearance of H Prep when incubated with brilliant Cresyl Blue in alpha-thalassaemias?

A

Typical golf ball appearance (30-90%)

This appearance is a characteristic finding in the H Prep test.

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16
Q

What peaks are identified in HPLC for alpha-thalassaemias?

A
  • Hb H peak
  • Hb Barts peak

These peaks indicate the presence of specific hemoglobin types associated with the disorder.

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17
Q

What role do family studies play in the diagnosis of alpha-thalassaemias?

A

Family studies

They help in understanding the inheritance patterns and potential genetic links.

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18
Q

What is the purpose of DNA analysis in diagnosing alpha-thalassaemias?

A

To confirm genetic mutation

DNA analysis provides definitive confirmation of the genetic basis of the disorder.

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19
Q

What is the hemoglobin level in β-Thalassemia Minor?

A

Slightly low (10–13 g/dL)

This indicates a mild reduction in hemoglobin levels.

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20
Q

What is the hemoglobin level in β-Thalassemia Major?

A

Very low (≤7 g/dL)

This reflects severe anemia in β-thalassemia major.

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21
Q

What is the MCV level in β-Thalassemia Minor?

A

Low (<80 fL, microcytic)

Indicates smaller than normal red blood cells.

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22
Q

What is the MCV level in β-Thalassemia Major?

A

Very low (<70 fL)

Signifies a more severe microcytic condition.

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23
Q

What is the RBC count in β-Thalassemia Minor?

A

Normal or high

This may vary but typically remains stable.

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24
Q

What is the RBC count in β-Thalassemia Major?

A

Markedly increased

Reflects the body’s attempt to compensate for severe anemia.

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25
Q

What findings are seen in the Peripheral Blood Smear of β-Thalassemia?

A
  • Microcytosis and hypochromia
  • Target cells (codocytes)
  • Basophilic stippling
  • Nucleated RBCs (normoblasts)
  • Anisocytosis & poikilocytosis

These findings help identify the severity and type of thalassemia.

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26
Q

What is the reticulocyte count in β-Thalassemia Minor?

A

Slightly increased

Indicates a mild increase due to the body’s response to low hemoglobin.

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27
Q

What is the reticulocyte count in β-Thalassemia Major?

A

Increased due to hemolysis

Reflects the body’s attempt to produce more red blood cells in response to anemia.

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28
Q

What is the gold standard test to identify abnormal hemoglobin levels?

A

Hemoglobin Electrophoresis (or HPLC)

This test is crucial for diagnosing various hemoglobinopathies.

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29
Q

What is the level of HbA in β-Thalassemia Minor?

A

Reduced (80–90%)

This indicates a decrease in normal hemoglobin due to thalassemia.

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30
Q

What is the level of HbA in β-Thalassemia Major?

A

Absent or very low

This is a key feature distinguishing major from minor.

31
Q

What is the level of HbA2 in β-Thalassemia Minor?

A

Increased (>3.5–7%)

Helps differentiate β-thalassemia minor from iron deficiency anemia.

32
Q

What is the level of HbF in β-Thalassemia Minor?

A

Normal/slightly high

Indicates fetal hemoglobin levels remain stable.

33
Q

What is the level of HbF in β-Thalassemia Major?

A

Very high (>90%)

Reflects the body’s compensation by producing fetal hemoglobin.

34
Q

What are the serum iron levels in β-Thalassemia?

A

Normal or high

This differentiates it from iron deficiency anemia.

35
Q

What are the serum iron levels in Iron Deficiency Anemia?

A

Low

This is a key indicator of iron deficiency.

36
Q

What is the ferritin level in β-Thalassemia?

A

Normal or high

Suggests adequate iron stores.

37
Q

What is the ferritin level in Iron Deficiency Anemia?

A

Low

Indicates depleted iron stores.

38
Q

What is the Total Iron Binding Capacity (TIBC) in β-Thalassemia?

A

Normal or low

This indicates that iron binding capacity is not elevated.

39
Q

What is the Total Iron Binding Capacity (TIBC) in Iron Deficiency Anemia?

A

High

Reflects the body’s attempt to increase iron uptake.

40
Q

What is the role of molecular/genetic testing in β-Thalassemia?

A

Confirms β-thalassemia mutations in the HBB gene

Useful for carrier screening, prenatal diagnosis, and in severe cases.

41
Q

What is the typical Hb level in Sickle Cell Anaemia?

A

Hb ↓(30-100 g/l)

42
Q

What are the key findings in a blood film for Sickle Cell Anaemia?

A
  • Hypochromic Microcytes
  • Target Cells
  • Sickle Cells
  • Polychromasia
  • NRBC
  • HJ bodies if hyposplenic
43
Q

What laboratory tests show increased levels in Sickle Cell Anaemia?

A
  • LDH ↑
  • Bilirubin ↑
44
Q

What is the significance of the Solubility Test in Sickle Cell Anaemia?

A

Positive result indicates the presence of Hb S

45
Q

What are the HPLC findings in Sickle Cell Anaemia?

A
  • Hb A absent
  • Hb S 80-100%
  • Hb F 5-15%
  • Increased HbA2
46
Q

What genetic analysis can confirm Sickle Cell Anaemia?

A

DNA analysis to confirm genetic mutation

47
Q

What are the types of thalassaemia based on globin chain synthesis?

A
  • α 0 or β 0 thalassaemias (complete absence)
  • α + or β + thalassaemias (reduced rate)
48
Q

What are the clinical divisions of thalassaemia?

A
  • Thalassaemia major: Severe anaemia, transfusion dependent
  • Thalassaemia intermedia: Severe to mild hypochromic microcytic anaemia
  • Thalassaemia minor: Clinically asymptomatic carrier state
49
Q

What is the pathophysiology of beta-thalassaemia related to globin chain synthesis?

A

Reduced or absent beta-globin production leads to excess alpha-globin chains

50
Q

What occurs due to alpha-globin precipitation in beta-thalassaemia?

A

Oxidative stress, membrane damage, and premature apoptosis of erythroid precursors

51
Q

What are the consequences of ineffective erythropoiesis in beta-thalassaemia?

A
  • Bone marrow expansion
  • Skeletal deformities
  • Extramedullary hematopoiesis leading to hepatosplenomegaly
52
Q

What causes iron overload in beta-thalassaemia?

A
  • Increased intestinal iron absorption
  • Repeated blood transfusions
53
Q

What are the normal alpha-globin gene structures?

A

HBA1 and HBA2 genes on chromosome 16 encode alpha-globin chains

54
Q

What is the effect of one gene deletion in alpha-thalassemia?

A

Silent Carrier: No symptoms, normal hemoglobin

55
Q

What characterizes Hemoglobin H (HbH) Disease?

A

Moderate-severe hemolytic anemia, splenomegaly, jaundice

56
Q

What is the genotype for Hemoglobin Bart’s Hydrops Fetalis?

A

−−/−− (Four alpha chain (HBA1+HBA2) gene deletions)

57
Q

What happens in alpha-thalassemia regarding globin chain production?

A

Deficiency of alpha-globin chains leads to excess beta and gamma globin chains

58
Q

What is the significance of Heinz Bodies?

A

Indicate precipitated unstable hemoglobin, seen in Hemoglobin H disease

59
Q

What causes Basophilic Stippling?

A

Aggregation of ribosomal RNA due to defective hemoglobin synthesis

60
Q

What do Pappenheimer Bodies indicate?

A

Iron overload due to defective hemoglobin production

61
Q

What is the appearance of Target Cells (Codocytes)?

A

RBCs with a bull’s-eye appearance

62
Q

What do Howell-Jolly Bodies signify?

A

Nuclear remnants in RBCs due to ineffective erythropoiesis or splenectomy

63
Q

What is the main treatment for severe forms of thalassemia?

A

Regular red blood cell transfusions

64
Q

What is the goal of blood transfusions in thalassemia treatment?

A

Maintain hemoglobin (Hb) levels around 9–10 g/dL

65
Q

What are the types of iron chelation therapy?

A

Iron overload therapy
* Deferoxamine (Desferal)
* Deferasirox (Exjade, Jadenu)
* Deferiprone (Ferriprox)

66
Q

What is the only curative option for β-thalassemia major?

A

Hematopoietic Stem Cell Transplantation

67
Q

What is an emerging treatment option for β-thalassemia?

A

Gene Therapy (Lentiviral-based gene therapy)

68
Q

Fill in the blank: Regular monitoring of serum ferritin and MRI scans is essential for _______.

A

iron overload assessment

69
Q

True or False: Splenectomy is considered for cases with massive splenomegaly or hypersplenism.

70
Q

HbH genetic mutation

A

3 alpha gene are deleted or mutated, leaving only one functional gene.
Excess beta globin chains form unstable tetramers = HbH
HbH has reduced oxygen carrying capacity and tend to precipitate damaging RBCs.

71
Q

Hb Barts genetic mutation

A

No alpha or beta globin chains.
Cannot form HbA or HbF.
To compensate cells make 4 y globin chains = HbBarts.
Extremely high affinity for oxygen so do not release oxygen efficiently to tissues

72
Q

Why is haptoglobin raised in a-thalassaemia?

A
  1. Increased RBC intravascular + extravascular haemolysis due to unstable Hb variants which precipitate and damage RBC membranes.
  2. Haptoglobin (plasma protein) binds free Hb released from lysed RBCs.
  3. haptoglobin-haemoglobin complex is cleared rapidly by the liver leading to low Haptoglobin levels.

Haematology (14 decks)

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