Zellweger syndrome is a disorder of –
**Core Concept**
Zellweger syndrome is a rare genetic disorder characterized by the deficiency of peroxisomes, which are organelles responsible for the breakdown of fatty acids and amino acids. This leads to the accumulation of very-long-chain fatty acids (VLCFAs) and other substances in the body, resulting in a range of systemic symptoms.
**Why the Correct Answer is Right**
The correct answer is related to the metabolic disturbances caused by the absence of functional peroxisomes. Peroxisomes contain enzymes such as acyl-CoA oxidase, which is necessary for the breakdown of VLCFAs. In Zellweger syndrome, the accumulation of VLCFAs leads to the activation of the pentose phosphate pathway, resulting in the production of reactive oxygen species (ROS) and subsequent oxidative stress. This oxidative stress can damage tissues and organs, leading to the characteristic symptoms of the disorder.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because Zellweger syndrome is not primarily a disorder of the mitochondria. While mitochondria are also involved in the breakdown of fatty acids, the primary defect in Zellweger syndrome is the absence of functional peroxisomes.
**Option B:** This option is incorrect because Zellweger syndrome is not primarily a disorder of the lysosomes. Lysosomes are involved in the breakdown of proteins and other substances, but the primary defect in Zellweger syndrome is related to the breakdown of fatty acids and amino acids by peroxisomes.
**Option C:** This option is incorrect because Zellweger syndrome is not primarily a disorder of the endoplasmic reticulum. The endoplasmic reticulum is involved in the synthesis and modification of proteins, but the primary defect in Zellweger syndrome is related to the breakdown of fatty acids and amino acids by peroxisomes.
**Clinical Pearl / High-Yield Fact**
Zellweger syndrome is one of a group of disorders known as the peroxisomal biogenesis disorders (PBDs), which are caused by mutations in genes involved in the assembly of peroxisomes. These disorders are characterized by the accumulation of VLCFAs and other substances, leading to a range of systemic symptoms.
**Correct Answer:** D. Peroxisomal biogenesis disorder.