Do beta thalassemia and sickle cell anemia always reduce life expectancy?

Not if just 1 trait: Having either beta thalassemia trait or sickle cell trait is a mild condition and should not cause symptoms to the point of making a person frequently ill nor shortening life expectancy. Having beta thalassemia major or sickle cell disease, or both sickle cell trait and beta thalassemia trait, usually causes severe enough chronic disease symptoms to shorten lifespan an uncertain amount.

Life expectancy : With clinically significant sickle syndromes or thalassemia syndromes is lower than for people without these afflictions, but are improving all the time. If you have trait for either condition, it should not have a measurable impact on your life expectancy.