A 3-year-old child has presented with abdominal lump and aniridia shown below. All genes are responsible for development of this condition except?
**Core Concept**
The condition described is a rare congenital disorder characterized by the absence of the iris (aniridia) and the presence of an abdominal lump, which is often a Wilms tumor. This condition is associated with mutations in specific genes involved in the development of the eye and the kidney.
**Why the Correct Answer is Right**
The correct answer is related to the genetic basis of aniridia and Wilms tumor. Aniridia is typically associated with mutations in the PAX6 gene, which is a transcription factor crucial for the development of the eye and the central nervous system. Wilms tumor, on the other hand, is often linked to mutations in the WT1 gene, which is involved in the development of the kidney and the gonads. The condition described is likely related to a contiguous gene deletion involving the PAX6 and WT1 genes.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the WT1 gene is responsible for the development of Wilms tumor and is often involved in the condition described. WT1 mutations lead to the disruption of the normal development of the kidney and gonads.
**Option B:** This option is incorrect because the PAX6 gene is crucial for the development of the eye and is often associated with aniridia. Mutations in PAX6 lead to the absence or underdevelopment of the iris.
**Option C:** This option is incorrect because the WT2 gene is not a recognized gene associated with Wilms tumor or aniridia. However, WT1 is the correct gene associated with Wilms tumor.
**Option D:** This option is incorrect because the PAX2 gene is not directly associated with aniridia. While PAX2 is involved in kidney development, PAX6 is the primary gene responsible for aniridia.
**Clinical Pearl / High-Yield Fact**
It's essential to recognize the association between aniridia and Wilms tumor, as these conditions are often linked to genetic mutations. The PAX6 and WT1 genes are critical in the development of the eye and kidney, respectively, and their mutations can lead to these congenital disorders.
**Correct Answer: C.**