How many genes are implicated in Alpha thalassemia?

Alpha thalassemia is primarily caused by mutations in the HBA1 and HBA2 genes, which are responsible for encoding the alpha globin chains of hemoglobin. There are four alpha globin genes located on chromosome 16, and the number of affected genes determines the severity of the condition:

• When one gene is mutated, the individual may have silent carrier status with minimal clinical impact.

• When two genes are mutated, it can lead to alpha thalassemia trait, usually causing mild anemia.

• When three genes are affected, the individual may have Hemoglobin H disease, which presents with moderate to severe anemia.

• When all four genes are mutated, it results in hydrops fetalis, typically lethal in utero.

Thus, the correct answer is that there are four genes involved in alpha thalassemia, which are implicated in the different forms and severities of the disease. Understanding this structure is crucial for diagnosing and managing alpha thalassemia properly in affected patients.