## **Core Concept**
Cerebrohepatorenal syndrome, also known as Zellweger syndrome, is a rare congenital disorder characterized by the reduction or absence of functional peroxisomes in the cells of the body. Peroxisomes are organelles involved in the breakdown of fatty acids and amino acids. One of the key features of this syndrome is the accumulation of very-long-chain fatty acids (VLCFAs) due to the deficiency of peroxisomal enzymes required for their beta-oxidation.

## **Why the Correct Answer is Right**
The correct answer, **Phytanic acid**, is a type of very-long-chain fatty acid that accumulates in the brain and other tissues of individuals with cerebrohepatorenal syndrome (Zellweger syndrome). This accumulation occurs because the syndrome leads to a deficiency in the peroxisomal enzymes necessary for the breakdown of phytanic acid. Phytanic acid is particularly notable because it is a branched-chain fatty acid that cannot be properly metabolized in individuals with this disorder.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While certain organic acids can accumulate in various metabolic disorders, the specific accumulation of **phytanic acid** is particularly associated with disorders of peroxisomal function, such as Zellweger syndrome.
- **Option B:** This option is not specified, but generally, disorders of amino acid metabolism can lead to accumulation of specific amino acids or their byproducts, not directly related to Zellweger syndrome.
- **Option D:** Similarly, this option is unspecified but considering the context, it does not relate to the specific biochemical abnormality seen in Zellweger syndrome.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl for Zellweger syndrome is that it presents with a combination of hypotonia, seizures, and characteristic facial features, along with hepatic dysfunction. The accumulation of very-long-chain fatty acids, including phytanic acid, is a biochemical hallmark. This syndrome is inherited in an autosomal recessive pattern, and diagnosis can be confirmed by genetic testing or by measuring very-long-chain fatty acid levels.

## **Correct Answer:** . Phytanic acid