**Question:** In sickle cell anemia hemoglobin electrophoresis shows all of the following, except:

A. Hemoglobin F (Fetal Hemoglobin)
B. Hemoglobin A2
C. Hemoglobin A (Adult Hemoglobin)
D. Hemoglobin C

**Correct Answer:** **Hemoglobin C**

**Core Concept:**
Hemoglobin electrophoresis is a laboratory test used to analyze the types of hemoglobin present in red blood cells. Sickle cell anemia is a genetic disorder characterized by the presence of abnormal hemoglobin molecules, primarily due to the presence of abnormal hemoglobin S (HbS) and hemoglobin A (HbA). Hemoglobin C (HbC) is another abnormal hemoglobin variant, but it is not the primary cause of sickle cell anemia.

**Why the Correct Answer is Right:**
In sickle cell anemia, the primary abnormality is in the HbS (sickle hemoglobin), which forms rigid, sickle-shaped red blood cells that cause hemolysis (destruction of red blood cells) and anemia. Hemoglobin C is a different abnormal hemoglobin variant, not associated with sickle cell anemia.

**Why Each Wrong Option is Incorrect:**

A. Hemoglobin F (HbF): Hemoglobin F is also known as fetal hemoglobin and is normally present in a high proportion in fetuses but decreases to minimal levels after birth. In sickle cell anemia, the presence of HbF is a protective factor, indicating the individual is not homozygous (HbSS) for the sickle cell trait but could be heterozygous (HbSC or HbSβ+thalassemia).

B. Hemoglobin A2 (HbA2): Hemoglobin A2 is another type of hemoglobin present in normal adults, accounting for approximately 2-3%. The presence of HbA2 does not distinguish between normal individuals and those with sickle cell trait or anemia, so it is not relevant to the diagnosis of sickle cell anemia.

C. Hemoglobin A (HbA): Hemoglobin A is the most common type of hemoglobin in adult red blood cells. Like HbA2, the presence of HbA is not specific to individuals with sickle cell anemia.

D. Hemoglobin C: As mentioned earlier, hemoglobin C is different from hemoglobin S and is not the primary cause of sickle cell anemia. Hemoglobin C is found in individuals with homozygous hemoglobin C disease, which is not the same as sickle cell anemia.

**Clinical Pearls:**

1. Sickle cell anemia is caused by the homozygous state of hemoglobin S (HbSS). The abnormal hemoglobin S polymerizes under reduced oxygen tension, leading to sickle-shaped red blood cells and vaso-occlusive crisis.
2. Hemoglobinopathies like sickle cell anemia and β-thalassemias involve abnormal hemoglobin production, leading to red blood cell abnormalities.
3. Hemoglobin electrophoresis is a valuable diagnostic tool in identifying abnormal hemoglobins, distinguishing between homozygous and heterozygous states, and detecting other hemoglobinopathies