Genetics of Alpha Thalassemia: What You Need to Know About the Genetic Inheritance of Alpha Thalassemia
Alpha thalassemia is a disorder of the blood in which the production of hemoglobin is reduced. Hemoglobin is a protein present in the red blood cells that is responsible for carrying oxygen to the body’s cells. Those who have this condition often have anemia, weakness, pale skin, and fatigue. More serious complications can also be present.
Understanding the genetics of alpha thalassemia can help patients to better understand the disease and why they, or their child, developed it.
Is Alpha Thalassemia Common?
This blood disorder is actually fairly common throughout the world. Thousands of babies are born every year with this blood disorder. Most babies born with this disease are in Southeast Asia, but this blood disorder also frequently occurs in people from North Africa, India, the Mediterranean countries, the Middle East and Central Asia.
What Genes are Associated with Alpha Thalassemia?
Deletions with the genes HBA2 gene and HBA1 are what typically cause alpha thalassemia. Both of these genes are responsible for the making of the protein alpha-globin. This protein is an element of hemoglobin. People have two copies of both of these genes per cell. Each of these copies is referred to as an allele.
For each gene, one allele is inherited from the patient’s mother, and the other allele is inherited from the patient’s father. Because of this four alleles create alpha-globin. This disorder occurs when some or all alleles are lost.
How is Alpha Thalassemia Inherited?
How this disorder is inherited and the genetics of thalassemia are complicated. Everyone inherits two alpha-globin alleles from their mother and two alpha-globin alleles from their father. If both the mother and the father are each missing just one of these alleles, the children that they produce could possibly be born with HbH disease, Hb Bart syndrome, or alpha thalassemia trait. The amount of alleles missing will determine a person’s exact risk of being born with this disease. The combination of genes affected can also determine this risk.
How is Thalassemia Treated?
How this disorder is treated will depend on the severity and type. Those whose symptoms that are mild may need no treatment. On occasion, a blood transfusion may be necessary, such as after having a baby, after surgery or if the patient develops an infection.
Those with more severe forms of this blood disorder often require blood transfusions frequently. They may need eight or more blood transfusions each year. If these transfusions result in too much iron building up in the blood, patients may need to take iron chelators to help flush out the extra iron.
In the most severe cases, a stem cell transplant or bone marrow transplant may be necessary.
Resources
Genetics Home Reference. (2009). Alpha Thalassemia. Retrieved on April 17, 2010 from Genetics Home Reference: https://ghr.nlm.nih.gov/condition=alphathalassemia
Mayo Clinic. (2009). Thalassemia. Retrieved on April 17, 2010 from the Mayo Clinic: https://www.mayoclinic.com/health/thalassemia/DS00905
Image Credits
DNA: svilen001 – sxc.hu
