A Chinese child with cardiomyopathy was diagnosed to have Keshan disease. Deficiency of which of the following results in Keshan disease?
**Core Concept**
Keshan disease is a congestive cardiomyopathy caused by a deficiency of a specific micronutrient, leading to impaired heart function and potentially life-threatening complications. This condition is characterized by an abnormal accumulation of fat in the heart muscle, resulting in decreased cardiac function.
**Why the Correct Answer is Right**
Keshan disease is caused by a deficiency of selenium (Se), an essential micronutrient that acts as a cofactor for several enzymes involved in antioxidant defense and thyroid hormone metabolism. Selenium deficiency disrupts the activity of glutathione peroxidase, an enzyme that protects cells from oxidative damage by reducing hydrogen peroxide. This impairment leads to the accumulation of toxic free radicals, ultimately causing damage to cardiac muscle cells.
**Why Each Wrong Option is Incorrect**
* **Option A:** While copper deficiency can cause cardiomyopathy, it is not associated with Keshan disease.
* **Option B:** Zinc deficiency can impair immune function and wound healing but is not directly linked to Keshan disease.
* **Option D:** Vitamin E deficiency can cause neurological symptoms and impaired immune function but is not the primary cause of Keshan disease.
**Clinical Pearl / High-Yield Fact**
Keshan disease is a classic example of a nutritional cardiomyopathy, highlighting the importance of adequate selenium intake for maintaining cardiac health. Selenium deficiency can be prevented by consuming selenium-rich foods, such as fish, Brazil nuts, and whole grains.
**Correct Answer:** C. Selenium.