**Question:** Babloo, a 4-year-old male presents with a history of seizures. On examination, there are hypopigmented patches on the face and mental retardation. Most probable diagnosis is:

A. Vitamin B12 deficiency
B. Vitamin D deficiency
C. Vitamin A deficiency
D. Vitamin E deficiency

**Correct Answer:** **C. Vitamin A deficiency**

**Core Concept:** Vitamin A plays a crucial role in maintaining normal vision, immune system function, and skin integrity. It is fat-soluble and essential for cell differentiation, growth, and repair.

**Why the Correct Answer is Right:** Vitamin A deficiency results in a condition known as xerophthalmia, which presents with night blindness (nyctalopia) and corneal ulcers leading to blindness. The patient's hypopigmented patches on the face and mental retardation are additional manifestations. Hypopigmented patches are a result of keratinization abnormalities, while mental retardation is due to the disruption of neuronal development and function.

**Why Each Wrong Option is Incorrect:**

A. Vitamin B12 deficiency: Babloo's symptoms do not align with the typical presentation of B12 deficiency, which often involves neurological symptoms like myelopathy and megaloblastic anemia.

B. Vitamin D deficiency: Although Vitamin D deficiency can cause rickets, it does not explain the hypopigmented patches and mental retardation seen in Babloo's case.

C. Vitamin A deficiency: As explained above, Vitamin A deficiency presents with hypopigmented patches and mental retardation, making it the correct answer.

D. Vitamin E deficiency: Vitamin E deficiency does not present with the described symptoms and is less likely to cause mental retardation compared to Vitamin A deficiency.

**Clinical Pearl:** Vitamin A deficiency should be suspected in infants and children with seizures, hypopigmented patches, and mental retardation, especially when there is a lack of other identifiable cause. Prompt intervention can prevent blindness and improve neurological outcomes.