What is the primary morphological change in hereditary spherocytosis?

In hereditary spherocytosis, the primary morphological change observed in red blood cells is that they become sphere-shaped. This condition is characterized by the loss of the normal biconcave disk shape of red blood cells due to a defect in the red cell membrane. The alteration in the membrane proteins (like spectrin and ankyrin) leads to an instability in the cell membrane, resulting in the formation of spherocytes—small, round red blood cells that appear more spherical than normal.

The spherical shape of these cells makes them less flexible, which can lead to difficulties in navigating through the small capillaries of the spleen. As a result, these abnormal cells are often sequestered and destroyed by the spleen, contributing to hemolytic anemia, an important clinical feature of hereditary spherocytosis. This change is a hallmark of the condition and helps in making a definitive diagnosis, often supported by clinical findings and laboratory tests.