sickle cell anaemia

I was doing some research on sickle cell anaemia and im slightly confused.
'Blood of patients with sickle cell anemia (SS) exhibits decreased affinity for oxygen, although the oxygen affinity of hemoglobin S is the same as that of hemoglobin A.' doesnt this mean that patients with SS bind less oxygen than those with haemoglobin A?

Reply 1

marble arch

Original post by Best Writer 254

I can clarify this for you. In patients with sickle cell anemia (SS), their hemoglobin, which is hemoglobin S (HbS), does indeed have the same oxygen affinity as hemoglobin A (HbA), which is the normal hemoglobin found in individuals without sickle cell anemia.

However, the statement you mentioned is pointing out a different phenomenon. In individuals with SS, the issue lies in the polymerization of HbS molecules when they release oxygen. When HbS molecules give up their oxygen, they can stick together and form long, rigid chains, causing the red blood cells to become misshapen (sickle-shaped) and leading to various complications. This polymerization doesn't occur with HbA.

So, while the oxygen affinity of HbS and HbA is the same, the way they behave after releasing oxygen is different, and this is what contributes to the reduced oxygen-carrying capacity and the characteristic symptoms of sickle cell anemia.