**Core Concept**
Hirschsprung disease is a congenital condition characterized by the absence of ganglion cells in the distal colon and rectum, leading to functional obstruction. It is a neurocristopathy, resulting from the failure of neural crest cells to migrate to the distal bowel during embryonic development.

**Why the Correct Answer is Right**
The correct answer is related to the association of Hirschsprung disease with other conditions that involve the migration or development of neural crest cells. One such condition is Down syndrome, which has a known association with Hirschsprung disease due to the presence of a mutation in the GDF5 gene. This gene plays a crucial role in the development of the enteric nervous system, and mutations in this gene can lead to the development of Hirschsprung disease.

**Why Each Wrong Option is Incorrect**
* **Option A:** Turner syndrome is a genetic disorder that affects females, characterized by the absence of one X chromosome. While it has various associated conditions, it is not directly related to Hirschsprung disease.
* **Option B:** Cystic fibrosis is a genetic disorder that affects the respiratory, digestive, and reproductive systems. It is caused by mutations in the CFTR gene and is not associated with Hirschsprung disease.
* **Option C:** Congenital rubella syndrome is a condition that occurs when a fetus is infected with the rubella virus during pregnancy. It can cause a range of complications, including heart defects and hearing loss, but is not associated with Hirschsprung disease.

**Clinical Pearl / High-Yield Fact**
Hirschsprung disease is often associated with other congenital anomalies, including gastrointestinal anomalies, such as esophageal atresia and intestinal atresia, and genitourinary anomalies, such as undescended testes.

**Correct Answer:** D. Down syndrome