Final answer:
Hemolytic anemias are caused by fragile, abnormally shaped erythrocytes due to mutations in hemoglobin, as seen in sickle cell anemia, where erythrocytes produce abnormal hemoglobin S.
Step-by-step explanation:
Hemolytic anemias are conditions where red blood cells are destroyed faster than they can be made. They are characterized by fragile, abnormally shaped erythrocytes, typically due to mutations. Sickle cell anemia is an example of a hemolytic anemia caused by a mutation in the hemoglobin genes.
In sickle cell anemia, erythrocytes produce an abnormal type of hemoglobin, known as hemoglobin S, which is responsible for the distinctive sickle or crescent shape of the cells. These sickle-shaped cells can cause blockages in narrow capillaries, leading to serious health problems. Therefore, the mutation that can lead to these fragile, abnormally shaped erythrocytes in hemolytic anemias has been traced to hemoglobin.