Which of the following conditions is not diagnosed by Chorionic Villous Biopsy?
**Core Concept**
Chorionic villous sampling (CVS) is a prenatal diagnostic test that involves removing a sample of chorionic villi from the placenta to detect genetic disorders. It is typically performed between 10-12 weeks of gestation.
**Why the Correct Answer is Right**
Since the correct answer choice is missing, let's discuss the general principle: CVS can diagnose conditions such as chromosomal abnormalities (e.g., **Down syndrome**), single-gene disorders (e.g., **cystic fibrosis**), and other genetic disorders by analyzing the **DNA** of the chorionic villi.
**Why Each Wrong Option is Incorrect**
**Option A:** Without the specific answer choices, we cannot directly address each option. However, generally, conditions that are not diagnosed by CVS include those that require **biochemical** or **functional** analysis not possible with DNA analysis alone.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that CVS is primarily used for detecting genetic abnormalities and not for conditions that require analysis of **amniotic fluid** or **fetal tissues** not sampled by CVS.
**Correct Answer:** D. Neural Tube Defects