Which defect is found in thalassemia?
The mutations associated with thalassemia are passed from parents to children. Hemoglobin molecules are made of chains called alpha and beta chains that can be affected by mutations. In thalassemia, the production of either the alpha or beta chains are reduced, resulting in either alpha-thalassemia or beta-thalassemia.
What chromosome is affected by thalassemia?
Each package is arranged into 23 pairs — with one of each pair coming from the mother and one from the father. When a child has alpha thalassemia, there is a change in chromosome 16. Alpha globin is made on chromosome 16.
What gene or chromosome is affected by beta thalassemia?
The beta globin (HBB) gene maps in the short arm of chromosome 11 in a region also containing the delta globin gene, the embryonic epsilon gene, the fetal A-gamma and G-gamma genes, and a pseudogene (ψB1).
Is thalassemia a single gene disorder?
In general, thalassemia is inherited in an autosomal recessive manner; however, the inheritance can be quite complex as multiple genes can influence the production of hemoglobin. Most people affected by beta thalassemia have mutations in both copies of the HBB gene in each cell .
How does thalassemia affect daily life?
People who have mild or minor forms of thalassemia can typically lead normal lives. In severe cases, heart failure is a possibility. Other complications include liver disease, abnormal skeletal growth, and endocrine issues.
Which thalassemia is most common?
Beta thalassemia is a fairly common blood disorder worldwide. Thousands of infants with beta thalassemia are born each year. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia.
What is the genetic cause of alpha thalassemia?
Alpha thalassemia occurs due to failure of one or more of the four alpha globin genes to produce alpha globin protein. The defect in alpha thalassemia is always due to the loss of one or more of the alpha globin genes from chromosome number 16.
What kind of hemoglobin does thalassemia have?
Thalassemia is characterized by an altered form of hemoglobin. Hemoglobin is a protein made of heme, alpha globins, and beta globins. Almost 9 different genes help in the production of heme and any changes in these genes may lead to disorders of heme production.
Where is the HBB gene located in thalassemia?
The hemoglobin beta gene (HBB) encodes the β-chain and is located on chromosome 11. In α-thalassemia, there is deficient synthesis of α-chains. The resulting excess of β-chains bind oxygen poorly, leading to a low concentration of oxygen in tissues (hypoxemia). Similarly, in β-thalassemia there is a lack of β-chains.
What happens to beta globin in beta zero thalassemia?
Some mutations in the HBB gene prevent the production of any beta-globin. The absence of beta-globin is referred to as beta-zero (β 0) thalassemia. Other HBB gene mutations allow some beta-globin to be produced but in reduced amounts.
What blood tests are done to detect thalassemia?
Abnormally shaped red blood cells are a sign of thalassemia. The lab technician may also perform a test known as hemoglobin electrophoresis . This test separates out the different molecules in the red blood cells, allowing them to identify the abnormal type.
What is the difference between thalassemia minor and major?
Thalassemia minor is a mild form of the disease in which the patient inherits only one mutated gene and act as a carrier. Thalassemia major is a severe form of the disease that can cause serious illness. Thalassemia is a group of genetic blood disorders that is characterized by destruction of red blood cells and hemoglobin higher than normal.
How did thalassemia get its name?
The name thalassemia comes from the ancient Greek word for sea, thalassa , as the ancients believed it was an “illness that came from the sea”. In 1925, pediatrician Thomas Benton Cooley published a work on thalassemia. This was the first description of the disorder, and for a long time it became known as Cooley’s anemia.
Is thalassemia a dominant or recessive?
Thalassemia is an inherited disease that may be inherited as an autosomal recessive or dominant trait depending on the type. Most thalassemias are inherited as recessive traits. Thalassemia is autosomal dominant in a very small percentage of beta thalassemia cases.