Answer:
The sickle-cell gene.
Step-by-step explanation:
The sickle cell mutation is in the gene encoding the β subunit. The sickle cell gene is located on the short arm (p) of chromosome 11, at position 15.5. Sickle cell anemia is a genopathy caused by a single mutation that results in the substitution of an amino acid in the β chains of the tetrameric protein hemoglobin. It characterized by the presence of sickle cells in the bloodstream, which are red cells or sickle-shaped erythrocytes. This form causes difficulty in the circulation of red blood cells. Confirmation of sickle cell anemia is obtained through tests that determine the presence and relative amount of hemoglobin S in a blood sample, that is, by checking the phenomenon of sickle cell disease, in a drop of blood between the slide and covers objects, or the presence of hemoglobin S by means of electrophoresis.