Final answer:
Sickle cell anemia is characterized by abnormal, sickle-shaped red blood cells caused by mutated hemoglobin S, which can block narrow capillaries and cause health complications.
Step-by-step explanation:
In sickle cell anemia, hemoglobin S causes erythrocytes to deform into a crescent or 'sickle' shape. The abnormal, elongated, and rigid shape of these cells can lead to them getting lodged in narrow capillaries, obstructing blood flow. This can cause various complications such as severe pain, organ damage, delayed growth, and strokes. Notably, hereditary spherocytosis (HS) is a different condition than sickle cell anemia, but it similarly results in abnormal red blood cells that can cause complications in the capillaries.