MEI LYN TAN
DR. SARAH SALM
BIO 425, Section 112
DECEMBER 14, 2005
- Thalassemia is one of the most common inherited genetic diseases.
- This disease is generally found among natives of Africa, Greece, Italy, Southeast Asia, Far East, Middle East and Southern China and in the last decade, North America.
WHAT IS THALASSEMIA?
- Thalassemia is a genetic blood disorder caused by mutated or missing genes.
- DNA consist of segments called genes, which are found in the chromosomes
- Two of these genes are responsible for the production of hemoglobin which is found in the red blood cells.
- Hemoglobin carries the Oxygen supply to the whole body and is essential for the body to function normally.
WHAT IS THALASSEMIA?
- The result of a missing or mutated gene causes the lack or absence of normal hemoglobin production.
- Due to this condition, the individual experiences varying degrees of anemia together with other illnesses that are associated with it.
WHAT HAPPENS IN A PERSON WITH THALASSEMIA?
- Alpha globins are located on Chromosome 16 and are produced by Alpha genes.
- Beta globins are located on Chromosome 11 and are produced by Beta genes.
- These genes contain the ‘blue print’ for making the specific globin chains.
- A balance between the chains produced on Chromosome 16 and 11 is necessary to enable the Hemoglobin to carry out its function efficiently.
- Due to a mutated or missing gene, often the balance has been affected in a person with Thalassemia.
- The amount and the quality of the globin chains produced determines the severity of the type of Thalassemia.
HOW TO DETECT THALASSEMIA?
- Hemoglobin electrophoresis test
- Complete blood count
- Normal reference range for Hemoglobin readings is 13.2 – 17.1 g/dL.
- Person with Thalassemia – below 13.2 g/dL.
- Iron level tests
HOW DOES A PERSON GET THALASSEMIA?
- A normal person has 46 Chromosomes, 23 from their father and 23 from their mother.
- All forms of Thalassemia are inherited, passed from parents who carry the mutated Thalassemia gene in their DNA, to their children.
GENETICS OF THALASSEMIA
- The following are the possibilities:
- If both parents do not carry the Thalassemia disease or trait, then the child would be normal
- If one parent carries the Thalassemia trait but the other is normal, then the child will have a 50% chance of inheriting the Thalassemia trait.
- If both parents have the Thalassemia trait, the child will have a 25% chance of inheriting the Thalassemia disease, 50% of inheriting the Thalassemia trait and a 25% chance of being normal.
- It is not medically possible to predict the order of occurrences.
TYPES OF THALASSEMIA
- There are four Alpha genes on Chromosome 16
- The variations of Alpha Thalassemia depend on the decreasing Alpha genes.
- Alpha Thalassemia is often categorized into the following :
- Silent Carrier
- Alpha Thalassemia trait
- Hemoglobin H disease
- Hemoglobin H-Constant Spring
- Alpha Thalassemia major or more commonly known as Hydrops Fetalis
TYPES OF THALASSEMIA
- The Beta Thalassemia is caused by mutations in the Beta globin gene.
- According to the Northern California Comprehensive Thalassemia Centre, 80% of these mutations consist of only 20 common types of mutations.
- Majority of Thalassemia incidences are of this form.
- Beta Thalassemia is often categorized into the following :
- Beta Thalassemia minor or trait
- Beta Thalassemia intermedia
- Beta Thalassemia major, often known as Cooley’s Anemia
EFFECTS OF THALASSEMIA
- Mild to severe Anemia
- Individuals with mild Anemia encounter:
- Shortness of breath
- Very often mistakenly diagnosed as having iron deficiency.
- Individuals with severe Anemia encounter
- Enlarged spleen
- Enlarged liver
- Heart palpitations
- Mild Jaundice
- Bone formation is defective, usually enlargement of the cheek bones
- Life expectancy and quality of life for individuals with severe Anemia is compromised.
TREATMENT OF THALASSEMIA
- An individual with only the Thalassemia trait would require to have :
- Regular Doctor visits every 2-6 times a year.
- Hemoglobin Levels tests
- Spleen Size
- Growth and Development Progress
- Bone Formation Abnormalities
- Bone Marrow Transplant
- Cord Blood Transplant
- Gene Replacement
- Fetal Hemoglobin Manipulation