Deposition of protein ‘A beta 2m’ is seen in which clinicopathologic category of amyloidosis –
**Core Concept**
Amyloidosis is a group of disorders characterized by the deposition of insoluble fibrils composed of various proteins in different tissues, leading to organ dysfunction. The deposition of protein 'A beta 2 microglobulin' is a specific type of amyloidosis.
**Why the Correct Answer is Right**
A beta 2 microglobulin (Aβ2M) amyloidosis is a rare condition associated with long-term hemodialysis. The deposition of Aβ2M occurs due to its accumulation in the serum of patients undergoing hemodialysis, leading to its aggregation and deposition in tissues, particularly in the bone, cartilage, and joints. This results in a clinical syndrome characterized by osteoarticular symptoms, including carpal tunnel syndrome, bone pain, and joint stiffness.
**Why Each Wrong Option is Incorrect**
**Option A:** Senile systemic amyloidosis is associated with the deposition of transthyretin (TTR), not Aβ2M.
**Option B:** AL amyloidosis is associated with the deposition of immunoglobulin light chains, not Aβ2M.
**Option C:** Hereditary transthyretin amyloidosis is caused by a mutation in the TTR gene, leading to the deposition of mutant TTR, not Aβ2M.
**Clinical Pearl / High-Yield Fact**
Aβ2M amyloidosis is a rare but serious complication of long-term hemodialysis, highlighting the importance of monitoring patients on dialysis for signs of amyloidosis and taking steps to prevent its development.
**Correct Answer: C. Hereditary transthyretin amyloidosis is caused by a mutation in the TTR gene, leading to the deposition of mutant TTR, not Aβ2M.