**Question:** The peripheral blood smear of a patient shows features of thalassemia, also presented with anaemia. Family history is also +ve. The investigation done to establish the diagnosis is:

A. Haemoglobin electrophoresis
B. Complete blood count (CBC)
C. Iron studies
D. Coomb's test

**Correct Answer:** A. Haemoglobin electrophoresis

**Core Concept:** Haemoglobin electrophoresis is a laboratory test used to analyze the type of haemoglobin present in red blood cells. In the context of thalassemia, this test can be helpful in diagnosing the type of thalassemia and determining the severity of the condition.

**Why the Correct Answer is Right:** Haemoglobin electrophoresis is the right answer because it allows for the precise identification of abnormal haemoglobin chains and the determination of the ratio of alpha and beta chains. This is crucial in diagnosing thalassemia, as the electrophoresis will reveal the type of thalassemia present (e.g., beta-thalassemia major, beta-thalassemia minor, etc.).

**Why Each Wrong Option is Incorrect:**

**A. Complete blood count (CBC)** and **D. Coomb's test**: Both options are important tests in the evaluation of anaemia, but they don't directly diagnose the specific type of thalassemia. CBC provides information on red cell indices, haemoglobin levels, and white blood cell count, but it doesn't differentiate between types of thalassemia. Coomb's test is used to evaluate the cause of haemolysis and is not specific to thalassemia diagnosis.

**C. Iron studies**: Iron studies, such as serum iron, total iron binding capacity (TIBC), and ferritin levels, are important for assessing iron status and anemia due to iron deficiency or overload. However, they are not specific to diagnose thalassemia, which is a genetic disorder affecting haemoglobin synthesis.

**Clinical Pearl:** Thalassemia is a group of inherited disorders characterized by abnormal haemoglobin synthesis. Haemoglobin electrophoresis is crucial in diagnosing and classifying thalassemia, while CBC and Coomb's test, as well as iron studies, are useful in evaluating the overall picture, but are not specific for thalassemia.