Okay, let's tackle this question. The question is about the deficiency of the hexosaminidase alpha (α) subunit. First, I need to remember which enzyme deficiency leads to which disease. Hexosaminidase is involved in breaking down GM2 gangliosides. The enzyme has different subunits, like alpha and beta.

If the alpha subunit is missing, that would affect the function of the enzyme. I think Tay-Sachs disease is related to hexosaminidase A deficiency. Let me confirm. Tay-Sachs is caused by a deficiency in hexosaminidase A, which is a combination of alpha and beta subunits. Without the alpha subunit, the enzyme can't break down GM2 gangliosides, leading to their accumulation in the brain.

The options probably include other lysosomal storage diseases. For example, Gaucher's is due to glucocerebrosidase deficiency, Niemann-Pick from sphingomyelinase, and Hunter's from iduronate sulfatase. Each of these enzymes is responsible for different substrates. So the correct answer here should be Tay-Sachs. Let me make sure I'm not confusing with Sandhoff disease, which is a deficiency of both alpha and beta subunits. But the question specifies the alpha subunit, so it's definitely Tay-Sachs.

**Core Concept**
Hexosaminidase A, composed of α and β subunits, is critical for degrading GM2 gangliosides. Its deficiency leads to substrate accumulation in lysosomes, causing neurodegenerative disease.

**Why the Correct Answer is Right**
Deficiency of the α subunit of hexosaminidase A results in **Tay-Sachs disease**. This enzyme hydrolyzes GM2 gangliosides into GM3. Without functional α subunits, GM2 accumulates in neurons, leading to progressive neurological deterioration, cherry-red spot in the retina, and early mortality.

**Why Each Wrong Option is Incorrect**
**Option A:** *Gaucher’s disease* results from glucocerebrosidase deficiency, not hexosaminidase.
**Option B:** *Niemann-Pick* is caused by sphingomyelinase deficiency, leading to sphingomyelin accumulation.
**Option C:** *Sandhoff disease* involves deficiency of both α and β subunits of hexosaminidase, not isolated α subunit.

**Clinical Pearl / High-Yield Fact**
Tay-Sachs is a classic autosomal recessive disorder with a "cherry-red spot" on funduscopic exam. It is most common in Ashkenazi Jewish populations. Remember **“Hex A deficiency = Tay-Sachs”** for exams.

**Correct Answer: C. Tay-Sachs disease**

✓ Correct Answer: A. Tay-Sachs disease