Which autoimmune disease is characterized by damage to the myelin sheath?

• A. Rheumatoid arthritis
• B. Multiple sclerosis
• C. Type-1 diabetes
• D. Graves disease

Answer: (B)

Multiple sclerosis (MS) is an autoimmune disease where the immune system mistakenly attacks the myelin sheath, which is the protective covering that surrounds nerve fibers in the central nervous system. This damage disrupts communication between the brain and the rest of the body, leading to a wide range of neurological symptoms such as weakness, coordination issues, and sensory disturbances.

In contrast, rheumatoid arthritis involves joint inflammation, type-1 diabetes is characterized by the destruction of insulin-producing cells in the pancreas, and Graves' disease is primarily associated with hyperthyroidism due to the overstimulation of the thyroid gland by autoantibodies. Each of these conditions has different pathophysiological mechanisms, but none directly address the myelin sheath as MS does. Therefore, the nature of damage to the myelin sheath is a key defining feature of multiple sclerosis, making it the correct answer.