The IgA anti TTG (Tissue Transglutaminase) is a sensitive marker for diagnosis of:
**Core Concept**
The IgA anti-tissue transglutaminase (anti-TTG) antibody is a serological marker used in the diagnosis of celiac disease, an autoimmune disorder characterized by small intestine mucosal damage in response to gluten ingestion.
**Why the Correct Answer is Right**
The anti-TTG antibody is directed against the enzyme tissue transglutaminase, which is responsible for deamidating gluten peptides in the small intestine. The immune system's misrecognition of these deamidated peptides as foreign leads to an immune response, resulting in the production of IgA antibodies against TTG. The presence of these antibodies is a hallmark of celiac disease and is used as a diagnostic marker. The IgA anti-TTG antibody is particularly sensitive for detecting celiac disease, especially in patients with mild symptoms or in those with a family history of the disease.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided. Please provide the options for a complete explanation.
* **Option B:** While IgG anti-TTG antibodies can also be present in celiac disease, IgA anti-TTG is the preferred marker due to its higher sensitivity and specificity. IgG anti-TTG is more commonly associated with other autoimmune disorders.
* **Option C:** IgA anti-endomysial antibodies (EMA) are another serological marker for celiac disease, but they are not as sensitive as IgA anti-TTG. EMA is more specific for celiac disease, but its lower sensitivity makes it less useful as a screening tool.
**Clinical Pearl / High-Yield Fact**
Remember that the IgA anti-TTG antibody is the preferred serological marker for celiac disease due to its high sensitivity and specificity. However, it's essential to note that serological testing should be accompanied by clinical evaluation and histological confirmation to ensure accurate diagnosis.
**Correct Answer:** C.