A 1-year-old boy with pale skin and eyes turns away from bright light. What is the likely cause of his skin color?

The scenario described suggests the child has symptoms consistent with albinism, which is characterized by a lack of pigmentation in the skin, hair, and eyes due to a genetic defect that affects melanin production.

The correct answer points to an inability to produce melanin, which can result from mutations affecting the enzyme tyrosinase or other factors involved in the melanin biosynthetic pathway. This lack of melanin leads to pale skin and eyes, making individuals more sensitive to bright light, as there is insufficient pigment to protect the skin and eyes from UV radiation. Albinism can cause visual problems as well, due to the lack of pigment in the retina.

In terms of the other options, aberrant migration of neural crest cells could impact various tissues during development, but it would not specifically lead to the deficiency in melanin production observed here. A decreased number of epidermal melanocytes might seem relevant, but the primary issue in albinism centers on the function of these cells rather than their quantity. Immune destruction of melanocytes is associated with conditions like vitiligo, which typically does not present with the features seen in this case, particularly in a young child.

Thus, the symptoms of the child strongly align with an inability to