Haemoglobinopathies and Thalassaemias Review Flashcards

Flashcards covering key concepts and details from the lecture on haemoglobinopathies and thalassaemias to aid in exam preparation.

What is a haemoglobinopathy?

A clinically diverse group of inherited disorders characterized by structural abnormalities or reduced synthesis of hemoglobin.

What distinguishes thalassaemias from structural haemoglobinopathies?

Thalassaemias involve a mutation that results in reduced or no synthesis of globin chains, while structural haemoglobinopathies involve mutations that produce abnormal hemoglobin.

What are the primary genes involved in the production of adult hemoglobin?

α globin genes on chromosome 16 and β, δ, and γ globin genes on chromosome 11.

Describe the change in hemoglobin type that occurs after birth.

Fetal hemoglobin (HbF, α2γ2) transitions to adult hemoglobin (HbA, α2β2) between 3-6 months after birth as γ chain production is replaced by β chain production.

What is the most common structural variant of hemoglobin?

Hemoglobin S (HbS), which is associated with sickle-cell disease.

What factors can predispose cells to sickling in sickle cell disease?

Hypoxia, acidosis, and increased body temperature.

How are sickle cell trait and sickle cell disease genetically classified?

Sickle cell trait is heterozygous (HbA+S) and typically asymptomatic, while sickle cell disease is homozygous (HbS+S) and leads to severe symptoms.

What are the clinical features of sickle cell disease?

Ulcers, dactylitis, susceptibility to infections, enlarged spleen, pulmonary hypertension, and increased risk of stroke.

What types of crises are associated with sickle cell disease?

Vaso-occlusive crises, sequestration crises, aplastic crises, and haemolytic crises.

What test is used for the diagnosis of sickle cell disease?

Hb electrophoresis, which can identify the presence of HbS and other hemoglobin variants.

What are the common causes of thalassaemias?

Genetic disorders leading to reduced or absent synthesis of α or β hemoglobin chains, often associated with geographical regions where malaria is endemic.

Identify the most severe form of α thalassaemia.

Hemoglobin Bart's hydrops fetalis, characterized by deletion of all four α globin genes.

What laboratory findings are indicative of β thalassemia major?

Marked microcytosis, hypochromasia, numerous target cells, and no HbA detected on electrophoresis.

What are potential treatments for individuals with severe β thalassemia?

Regular blood transfusions, iron chelation therapy, splenectomy, and bone marrow transplant.

What is the expected prognosis for individuals with untreated β thalassemia?

A life expectancy of around five years.

What defines a silent carrier of α thalassaemia?

Individuals who have a deletion in one globin gene without any hematological abnormalities, only identifiable through DNA analysis.