Question

A child demonstrates progressive neurological decline and a cherry-red spot on fundus examination. Enzyme analysis reveals a deficiency in hexosaminidase A. What is the most likely diagnosis?

• A. GM1 gangliosidosis
• B. GM2 gangliosidosis
• C. Niemann--Pick disease
• D. Gaucher disease

Hint:

Hexosaminidase A deficiency + cherry-red spot + neurodegeneration = Tay--Sachs disease GM2 gangliosidosis.

Answer 1

The Correct Option is B

Concept: Hexosaminidase A deficiency causes Tay--Sachs disease, which is a GM2 gangliosidosis. It presents with progressive neurodegeneration and cherry-red spot on the macula.

Step 1: Identify the enzyme deficiency.
The enzyme deficient is: \[ \text{Hexosaminidase A} \] This is the classic enzyme defect in Tay--Sachs disease.

Step 2: Connect with accumulated substance.
In Tay--Sachs disease, there is accumulation of: \[ \text{GM2 ganglioside} \]

Step 3: Match with clinical findings.
Progressive neurological decline with cherry-red spot strongly supports GM2 gangliosidosis. Therefore, the correct answer is GM2 gangliosidosis.