5.5 Sickle Cell Anemia

Health Problems Associated with Mutant Hemoglobin

Figure 5.18: Health Problems Associated with Mutant Hemoglobin

A mutation in the amino acid sequence of hemoglobin can result in a myriad of health problems (as seen in figure 5.18).

Mutant (right) and Healthy Hemoglobin (left)

Figure 5.19: Mutant (right) and Healthy Hemoglobin (left)

Nonetheless, sickle cell anemia is the result of a single amino acid mutation relative to healthy hemoglobin. The mutation renders the healthy hemoglobin prone to polymerization (into fibers), hence causing red blood cells to elongate and deform in a way (see figure 5.19) that renders them fragile (hence also blocking capillaries).

Schematic of Fibers Present in Sickle Cell Anemia

Figure 5.20: Schematic of Fibers Present in Sickle Cell Anemia

In sickle cell anemia, Val6 is converted to Glu6 in the \(\beta\) subunit, hence creating a “sticky” patch that happens to bind to another location in the \(\beta\) chain.

This binding (shown in figure 5.20) is what allows polymerization to occur for hemoglobin molecules in the T state.