One Would Expect That Defects in the Globin Genes Would $\beta$

Multiple Choice

One would expect that defects in the globin genes would be so serious as to cause death in utero. Which of the following explains how some thalassemias are found in living people?

A) in $\beta$ -thalassemia, the use of the $\gamma$ subunit allows individuals to live a normal lifespan
B) individuals who completely lack functional $\alpha$ subunits can live if placed in a hypobaric chamber to induce hypoxia
C) since humans have 4 copies of the $\alpha$ chain gene, effects are only seen when at least 3 of the genes are nonfunctional
D) individuals with nonfunctional $\alpha$ chain genes can make $\beta$ ₂ $\gamma$ ₂ tetramers that function normally
E) none of the above