Final answer:
The mutation in the β-chain that causes hemoglobin to have a high affinity for oxygen leads to a condition called Polycythemia. It is not related to sickle cell anemia, which also involves a β-chain mutation but results in a different clinical phenotype characterized by sickled red blood cells.
Step-by-step explanation:
The clinical phenotype associated with a β-chain mutation that locks the hemoglobin into the relaxed state, with a high affinity for oxygen, is Polycythemia. This condition is characterized by an abnormal increase in the number of red blood cells, which can result from a high oxygen affinity leading to increased hemoglobin saturation. The β-chain mutation in question is not the same as the one found in sickle cell anemia, which involves the substitution of glutamic acid with valine leading to sickle-shaped red blood cells.
Sickle cell anemia (HbS) and β-thalassemia are both results of β-chain mutations but lead to different clinical manifestations. While sickle cell anemia is characterized by the abnormal shaping and function of red blood cells due to the aggregation of hemoglobin molecules, β-thalassemia involves the reduced synthesis of β-chains, which impairs oxygen transport.