Thalassaemia Flashcards
explain the different genotypes and outcomes associated with alpha-thalassemia
Number of Gene Deletions: 1
Genotype: (aa/a-)
Disease Name: Alpha-Thalassemia Minor
Outcome: Silent Carrier
Number of Gene Deletions: 2
Genotype: (a-/a-)
Disease Name: Alpha-Thalassemia Minor 2 or Alpha-Thalassemia Trait
Outcome: Mild Anemia
Number of Gene Deletions: 2
Genotype: (aa/–)
Disease Name: Alpha-Thalassemia Minor 1 or Alpha-Thalassemia Trait
Outcome: Mild Anemia, Worsens with Successive Generations
Number of Gene Deletions: 3
Genotype: (a-/–)
Disease Name: Hemoglobin H (HbH)
Outcome: Mild to Severe Anemia
Number of Gene Deletions: 4
Genotype: (–/–)
Disease Name: Alpha-Thalassemia Major or HbBarts
Outcome: Incompatible with Life, Causes Hydrops Fetalis
explain the different presentations and outcomes associated with various alpha-thalassemia genotypes
Normal:
Individuals with a normal complement of alpha-globin genes are asymptomatic and do not exhibit any abnormalities related to alpha-thalassemia.
Carrier (Silent Carrier):
Alpha-thalassemia carriers, also known as silent carriers, are asymptomatic and do not manifest any clinical abnormalities. They typically have one alpha-globin gene deletion.
Alpha-Thalassemia Minor:
Individuals with alpha-thalassemia minor are asymptomatic but may have mild microcytic anemia, a condition characterized by small red blood cells. This form often results from the deletion of two alpha-globin genes.
Hemoglobin H (HbH) Disease:
HbH disease is a symptomatic form of alpha-thalassemia, resulting from the deletion of three alpha-globin genes. It is associated with hemolytic anemia, in which red blood cells are prematurely destroyed, leading to anemia. Microcytosis and splenomegaly (enlarged spleen) are common features of HbH disease.
Incompatible with Life, Hydrops Fetalis:
A condition resulting from the deletion of all four alpha-globin genes is incompatible with life and causes hydrops fetalis, a severe form of anemia. This condition is not viable and leads to fetal hydrops.
describe a sequence of events and symptoms that can occur in individuals with various conditions that affect red blood cells, such as anemias, including those associated with thalassemia and other hemolytic disorders
Malformed Red Blood Cells: Certain conditions, including thalassemias and other hemolytic disorders, can lead to the production of malformed or abnormal red blood cells. These cells may have altered shapes, sizes, or compositions.
Reduced Oxygen-Carrying Capacity (Anemia): Malformed red blood cells can result in reduced oxygen-carrying capacity of the blood, leading to anemia. Anemia is a condition in which the blood lacks an adequate number of healthy red blood cells, reducing the oxygen available to tissues and organs.
Symptoms of Anemia: Anemia is associated with various symptoms, including:
Pallor (pale skin and mucous membranes)
Shortness of breath, especially upon exertion
Feeling cold
Weakness and fatigue
Body Removes Damaged Red Cells: The body’s immune system recognizes and removes damaged or abnormal red blood cells from circulation.
Enlarged Spleen (Splenomegaly): The increased workload of filtering out and destroying damaged red blood cells can cause the spleen to enlarge. This condition is known as splenomegaly.
Low Numbers of Red Blood Cells: The removal of damaged red blood cells can lead to a decreased overall count of red blood cells in the circulation, contributing to anemia.
Jaundice: The breakdown of red blood cells can release a pigment called bilirubin, which, when accumulated in the body, can lead to jaundice. Jaundice is characterized by yellowing of the skin and eyes.
outline the management and treatment options for individuals with certain types of anemia, particularly those associated with conditions such as thalassemia and other hereditary hemolytic disorders
Anemia Management:
For individuals with anemia, management often involves addressing the underlying cause. In some cases, anemia can be managed by supplementing with folic acid and ensuring proper nutrition to support red blood cell production.
Transfusions of Packed Red Cells:
In cases of severe anemia, especially in hemolytic disorders, transfusions of packed red blood cells may be required to increase the red blood cell count and improve oxygen-carrying capacity. Frequent transfusions can lead to iron overload.
Iron Overload:
Frequent blood transfusions can lead to iron overload in the body. This excess iron can be harmful to organs and tissues.
Long-Term Management Options:
In cases where anemia is chronic and associated with a hereditary disorder like thalassemia, long-term management options may include:
Bone marrow transplant: This procedure may be considered as a potential cure for certain hereditary blood disorders.
Splenectomy: The removal of the spleen can help manage complications related to anemia in some cases.
Avoiding Passing on the Condition:
Genetic Counseling: To prevent the condition from being passed on to future generations, individuals with hereditary anemias may seek genetic counseling. This involves discussing the genetic risk and inheritance patterns and considering options like carrier testing, prenatal testing, and family planning.
explain beta-thalassaemia
β (Beta): This refers to the normal allele of the beta-globin gene.
β+ (Beta Plus): In cases of β+ thalassemia, partial function of the beta-globin gene is conserved, but it may still result in reduced function or a reduced quantity of beta-globin production.
β0 (Beta Zero): In instances of β0 thalassemia, no functioning beta-globin protein is synthesized. This leads to a more severe form of the condition.
The severity of beta-thalassemia is influenced by the specific mutation(s) in the beta-globin gene. Individuals can be carriers (heterozygous) with one affected allele and one normal allele, or they can have the condition (homozygous) with two affected alleles, resulting in more pronounced symptoms.
Management and treatment of beta-thalassemia may involve blood transfusions, iron chelation therapy to manage iron overload, and, in severe cases, bone marrow transplantation. Genetic counseling is also an important aspect for families at risk of carrying or passing on beta-thalassemia-related mutations.
explain the different alleles and their associated conditions in beta-thalassemia.
Alleles: b/b
Name: Normal
Description: Healthy, with no mutations in the beta-globin gene.
Alleles: b/b+
Name: Beta-Thalassemia Minor
Description: One allele has a mutation, resulting in mild anemia. Mean Corpuscular Volume (MCV) is typically less than 80 femtoliters (fL).
Alleles: b+/b0
Name: Beta-Thalassemia Intermedia
Description: Occasional need for blood transfusions, for example, during pregnancy. This condition is intermediate in severity.
Alleles: b0/b0, b+/b+
Name: Beta-Thalassemia Major
Description: Both alleles have mutations, resulting in severe microcytic anemia, bone deformities, and early death despite the need for multiple transfusions.
