What are my risks of having a child with beta thalassemia if I have one defective HBB gene?

There is a 50% chance that a carrier of beta thalassemia (or beta thalassemia minor) will pass the defective copy of the HBB gene to their children. If two carriers have a child, there is a 25% chance that the child will inherit two defective HBB genes and suffer from beta thalassemia