Which abnormal hemoglobin causes rigid red blood cells with short life spans?

The abnormal hemoglobin that causes rigid red blood cells with short life spans is hemoglobin S (HgS). This form of hemoglobin is associated with sickle cell disease, a condition where the red blood cells become rigid and assume a sickle shape under low oxygen conditions. These rigid sickle cells can become trapped in small blood vessels, leading to pain and various complications. Additionally, they have a significantly reduced lifespan compared to normal red blood cells, typically lasting only 10 to 20 days instead of the usual 120 days.

The other hemoglobins mentioned do not lead to the same pattern of rigidity and lifespan issues associated with sickle cell disease. Hemoglobin C (HgC) can cause some red cell abnormalities, but they are different from the specific rigidity and lifespan issues seen with hemoglobin S. Methemoglobin is a form of hemoglobin that cannot effectively release oxygen to the tissues, affecting oxygen transport but not directly causing cell rigidity or shortening their lifespan. Hemoglobin A is the normal adult hemoglobin and does not possess these abnormal characteristics. Thus, hemoglobin S is identified as the cause of rigid red blood cells associated with sickle cell disease, leading to their short lifespan.