## Core Concept
The question pertains to metabolic disorders where clinical features arise from the accumulation of toxic compounds. These disorders often result from deficiencies in enzymes that are crucial for metabolizing certain substances, leading to their accumulation and subsequent toxicity.

## Why the Correct Answer is Right
Phenylketonuria (PKU) is a condition characterized by the inability to break down the amino acid phenylalanine (Phe), which then accumulates and can lead to intellectual disability and other serious health problems if not treated. This accumulation of phenylalanine is toxic to the developing brain. On the other hand, **Gaucher's disease** is a genetic disorder caused by a deficiency of the enzyme glucocerebrosidase, leading to an accumulation of glucocerebroside within cells. However, the primary issue in Gaucher's disease is not the toxicity of the accumulated substance per se but rather the cellular dysfunction and organomegaly caused by the accumulation of glucocerebroside.

## Why Each Wrong Option is Incorrect
- **Option A (not provided):** Without specific details on Option A, we cannot directly address its incorrectness.
- **Option B (not provided):** Similarly, lacking specifics on Option B, we cannot discuss its incorrectness.
- **Option C (not provided):** Without information on Option C, we cannot evaluate its incorrectness.

## Why Option D (presumably the correct answer) is Right and Others are Wrong
Given that **Gaucher's disease** involves the accumulation of a substance (glucocerebroside) that leads to cellular dysfunction rather than direct toxicity from the accumulated compound, it stands out from disorders primarily characterized by toxic accumulations.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while many metabolic disorders result from the accumulation of toxic substances, others, like Gaucher's disease, are more accurately described as resulting from the accumulation of substances that lead to cellular dysfunction and organ damage rather than direct toxicity.

## Correct Answer: D. Gaucher's disease