**Question:** All are examples of hereditary neuropathies associated with abnormal lipid
metabolism, EXCEPT:

A. Charcot-Marie-Tooth disease
B. Fabry disease
C. Tay-Sachs disease
D. Krabbe disease

**Core Concept:** Hereditary neuropathies are a group of disorders that affect the peripheral nerves, leading to various degrees of nerve dysfunction. Abnormal lipid (fat)
metabolism can lead to misfolding and accumulation of lipids in neurons, resulting in nerve damage. The correct answer should be a disorder with a different etiology.

**Why the Correct Answer is Right:**
C. Tay-Sachs disease is a disorder caused by a deficiency of the enzyme hexosaminidase A, which results in the accumulation of ceramide trihexoside in neurons. It is not associated with abnormal lipid
metabolism.

**Why Each Wrong Option is Incorrect:**
A. Charcot-Marie-Tooth disease (CMT) is a group of disorders characterized by degeneration of peripheral nerves. It is associated with mutations in genes involved in myelin production or function, not lipid
metabolism.

B. Fabry disease is caused by a deficiency of the enzyme alpha-galactosidase A, leading to the accumulation of globotriaosylceramide in various tissues, including neurons. It is related to lipid
metabolism.

D. Krabbe disease is caused by a deficiency of the enzyme galactocerebrosidase, which results in the accumulation of galactosylsphingosine in neurons. It is also related to lipid
metabolism.

**Clinical Pearl:**
Understanding the underlying etiology of various hereditary neuropathies is essential for identifying the correct diagnosis and appropriate management strategies. In this case, knowing that Tay-Sachs disease is not associated with lipid
metabolism helps in distinguishing it from disorders like CMT, Fabry disease, and Krabbe disease, which are indeed related to lipid
metabolism.

**Correct Answer:** C. Tay-Sachs disease (Hereditary Acanthocytosis)

**Why Each Wrong Option is Incorrect:**
A. Charcot-Marie-Tooth disease (Hereditary Neuropathy)
B. Fabry disease (Lysosomal Storage Disease)
D. Krabbe disease (Lysosomal Storage Disease)