What Is Beta Thalassemia?
Beta thalassemia is a type of inherited blood disorder that can cause anemia (a low number of red blood cells). It affects a person's ability to produce hemoglobin, the protein in red blood cells that delivers oxygen to all parts of the body.
Signs and symptoms of beta thalassemia are severe in the form of the disorder known as thalassemia major and less severe in the form called thalassemia intermedia. Signs and symptoms of thalassemia major appear in the first 2 years of life. Infants become pale and listless, have a poor appetite, grow slowly, and often develop jaundice (yellowing of the skin). The spleen, liver, and heart may also be enlarged. Adolescents with the severe form may experience delayed puberty. Individuals with thalassemia intermedia may have no symptoms or mild symptoms through childhood and adolescence.
How Common Is Beta Thalassemia?
Worldwide, beta thalassemia is considered a fairly common blood disorder, affecting thousands of infants each year. Beta thalassemia occurs most frequently in Mediterranean countries, North Africa, the Middle East, India, and southeast Asia. In North America, the disorder is less common; an estimated 750-1000 people have beta thalassemia.
What Genes Are Related to Beta Thalassemia?
Mutations in the HBB gene cause beta thalassemia.
The HBB gene produces one of the subunits of hemoglobin, called beta hemoglobin or the beta chain. Mutations in the HBB gene can reduce or abolish the production of betahemoglobin, leading to abnormal hemoglobin that cannot perform its function as an oxygen carrier.
How Do People Inherit Beta Thalassemia?
Beta thalassemia major and thalassemia intermedia are inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder. Sometimes, however, carriers of the altered HBB gene have a mild anemia referred to as thalassemia minor.
In a small percentage of families, the HBB mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is sufficient to cause the disorder.
Beta thalassemia is a type of inherited blood disorder that can cause anemia (a low number of red blood cells). It affects a person's ability to produce hemoglobin, the protein in red blood cells that delivers oxygen to all parts of the body.
Signs and symptoms of beta thalassemia are severe in the form of the disorder known as thalassemia major and less severe in the form called thalassemia intermedia. Signs and symptoms of thalassemia major appear in the first 2 years of life. Infants become pale and listless, have a poor appetite, grow slowly, and often develop jaundice (yellowing of the skin). The spleen, liver, and heart may also be enlarged. Adolescents with the severe form may experience delayed puberty. Individuals with thalassemia intermedia may have no symptoms or mild symptoms through childhood and adolescence.
How Common Is Beta Thalassemia?
Worldwide, beta thalassemia is considered a fairly common blood disorder, affecting thousands of infants each year. Beta thalassemia occurs most frequently in Mediterranean countries, North Africa, the Middle East, India, and southeast Asia. In North America, the disorder is less common; an estimated 750-1000 people have beta thalassemia.
What Genes Are Related to Beta Thalassemia?
Mutations in the HBB gene cause beta thalassemia.
The HBB gene produces one of the subunits of hemoglobin, called beta hemoglobin or the beta chain. Mutations in the HBB gene can reduce or abolish the production of betahemoglobin, leading to abnormal hemoglobin that cannot perform its function as an oxygen carrier.
How Do People Inherit Beta Thalassemia?
Beta thalassemia major and thalassemia intermedia are inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder. Sometimes, however, carriers of the altered HBB gene have a mild anemia referred to as thalassemia minor.
In a small percentage of families, the HBB mutation is inherited in an autosomal dominant manner. In these cases, one copy of the altered gene in each cell is sufficient to cause the disorder.