Introduction to Abnormal Haemoglobins

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Questions and Answers

What genotype is associated with β-thalassaemia minor?

β+/β0

β/β+ (correct)

β+/β+

β0/β0

Which clinical feature is least likely to be seen in a patient with α-thalassaemia carrier?

Splenomegaly

Asymptomatic

Hb H disease

Moderate anaemia (correct)

Which description accurately reflects the most severe form of β-thalassaemia?

Normal growth and development

Asymptomatic with no significant findings

Mild anaemia with no organomegaly

Severe anaemia with growth retardation (correct)

Which statement accurately describes the consequences of α4 deletion?

Results in hydrops and is incompatible with life Signup and view all the answers

What is the main pathological characteristic of β-thalassaemia intermedia?

Moderate anaemia with possible hepatosplenomegaly Signup and view all the answers

Which condition is described as being incompatible with life due to α-thalassaemia?

Hydrops fetalis Signup and view all the answers

Which statement correctly describes the effect of pathological hemoglobin variants?

They can affect oxygen carrying capacity and red cell lifespan. Signup and view all the answers

What is the common clinical feature of β-thalassaemia major?

Severe anaemia and hepatosplenomegaly Signup and view all the answers

What is the expected clinical feature of HbH disease?

Mild to moderate hemolytic anaemia Signup and view all the answers

At what point in severity do thalassaemias become incompatible with life?

With specific mutations causing severe imbalances Signup and view all the answers

What is the primary characteristic that differentiates a quantitative defect from a qualitative defect in hemoglobin?

Qualitative defects involve structural variants of globin chains. Signup and view all the answers

Which of the following is not a variant type associated with qualitative structural defects in hemoglobin?

HbH Signup and view all the answers

What distinguishes α-thalassaemia from α-thalassaemia carrier status?

Both carriers and α-thalassaemia patients are generally asymptomatic. Signup and view all the answers

Which statement correctly describes the relationship between α-thalassaemia and microcytic anemia?

Mild microcytic anemia can occur in α-thalassemia minor. Signup and view all the answers

In β-thalassaemia, which characteristic is true regarding the synthesis of globin chains?

β-thalassaemia causes a reduced synthesis of β-globin chains. Signup and view all the answers

What is a notable symptom of HbH disease?

Symptomatic microcytic anemia Signup and view all the answers

Which of the following correctly relates to hydrops fetalis in α-thalassemia?

Hydrops fetalis is an advanced manifestation of severe α-thalassemia. Signup and view all the answers

Which amino acid substitution characterizes HbS variant?

Glu-6-Val Signup and view all the answers

Which of the following traits is NOT associated with α-thalassaemia?

Carriers exhibit severe clinical symptoms. Signup and view all the answers

What is the primary consequence of qualitative structural defects in hemoglobin?

Altered function or stability of the hemoglobin molecules. Signup and view all the answers

Study Notes

Introduction to Abnormal Heritable Haemoglobins

Haemoglobinopathies are abnormal haemoglobins.
Many haemoglobin variants are clinically silent.
Pathological variants affect oxygen-carrying capacity, haemoglobin solubility, or red blood cell lifespan.
Thalassaemias involve globin chain imbalances.

Learning Objectives

Differentiate between quantitative and qualitative structural haemoglobin defects.
Compare and contrast α and β thalassaemia subtypes.

Heritable Haemoglobin Variants

Quantitative defects (amount) involve reduced synthesis of normal globin chains (thalassaemias).
Qualitative defects (quality) involve structural variants in haemoglobin.
- Examples: HbS, HbC, HbD, HbE, Glu-6-Val, Glu-6-Lys, Glu-121-Gln, Glu-26-Lys

Alpha-Thalassaemia

Normal: α α α α
Carrier: α α α - (asymptomatic, no symptoms)
α-thal minor: α α - - (mild microcytic anaemia)
HbH disease: α - - - or α - - - (Symptomatic, microcytic anaemia, splenomegaly)
Hydrops foetalis: - - - - (Incompatible with life)

Beta-Thalassaemia

Normal: β β
Minor: β β (asymptomatic, no symptoms)
Intermedia: β β, β+/β0 (Mild anaemia, splenomegaly)
Major: β0/β0 (severe anaemia, hepatosplenomegaly, growth retardation).

Thalassaemias

β Thalassaemia (Genotype/Clinical features)
- Carrier/trait (β+/β+, β/0): Normal to mild anaemia, no organomegaly
- Intermedia (β+/β+, β+/β0): Mild anaemia, hepatosplenomegaly
- Major (β0/β0): severe anaemia, hepatosplenomegaly, growth retardation
α Thalassaemia (Genotype/Clinical features)
- α-thal carrier (αα/-α, -α/-α or αα/--): Asymptomatic
- HbH disease (-α/--): moderate to severe hemolytic anemia, moderate ineffective erythropoiesis, splenomegaly, variable bone changes.
- Hb Barts/hydrops foetalis (--/--): incompatible with life

Consequences of α4 Deletion

Decreased Hb synthesis.
Most Hb is Hb Bart's.
Tissue hypoxia.
Maternal complications like preeclampsia, hypertension, and retained placenta.
Heart failure, extra-medullary erythropoiesis, and organogenesis issues.

Summary

Haemoglobinopathy describes abnormal haemoglobins.
Thalassaemia involves globin chain imbalances.
Clinical severity varies from clinically silent to incompatible with life.

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Description

Explore the fascinating world of haemoglobinopathies in this quiz. Understand how different variants affect oxygen transport and the implications of thalassaemias. Test your knowledge on the structural defects and the classifications of these abnormal haemoglobins.