## Core Concept
Wilms tumor, also known as nephroblastoma, is a type of kidney cancer that primarily affects children. It is associated with several genetic and clinical features, including **WT1 gene mutations**, **Beckwith-Wiedemann syndrome**, and **Denys-Drash syndrome**. These conditions often present with abdominal masses and may have additional characteristics such as hemihypertrophy.

## Why the Correct Answer is Right
The correct answer can be deduced by understanding the common associations with Wilms tumor. Features like **aniridia**, **genitourinary anomalies**, and **hemihypertrophy** are well-documented associations. However, certain conditions or features are not typically linked with Wilms tumor.

## Why Each Wrong Option is Incorrect
- **Option A:** Aniridia is associated with Wilms tumor, particularly in the context of **WAGR syndrome** (Wilms tumor, Aniridia, Genitourinary anomalies, and mental Retardation), which is linked to **WT1 gene mutations**.
- **Option B:** Hemihypertrophy, also known as hemihyperplasia, is a feature seen in **Beckwith-Wiedemann syndrome**, which increases the risk for Wilms tumor.
- **Option C:** Genitourinary anomalies are also associated with Wilms tumor, especially in the context of **Denys-Drash syndrome**, another condition related to **WT1 mutations**.

## Why the Correct Answer (D) is Correct and the Rest are Incorrect
- **Option D:** Typically, **DiGeorge syndrome** (also known as 22q11.2 deletion syndrome) is characterized by thymic hypoplasia, leading to immunodeficiency, heart defects, and cleft palate. It is not commonly associated with an increased risk of Wilms tumor.

## Clinical Pearl / High-Yield Fact
A key clinical pearl is that children with Wilms tumor may present with an abdominal mass, and certain genetic syndromes increase the risk. **WT1 gene mutations** are a critical genetic link to Wilms tumor, particularly in syndromes like Denys-Drash and WAGR.

**Correct Answer: D. DiGeorge syndrome**