Question

A 10 month old child presents with weakness, coarse facial features, and a normal ECG. What is the likely diagnosis?

• A. Hurler syndrome
• B. Hunter syndrome
• C. Glycogen storage disorder
• D. Phenylketonuria

Hint:

Hurler syndrome damages the heart early with an abnormal ECG; Hunter syndrome is milder, so a normal ECG favours Hunter.

Answer 1

The Correct Option is B

This question is comparing Hurler and Hunter syndrome, two mucopolysaccharide storage disorders that look alike on the surface but differ in how badly they affect the heart.

1. Hurler syndrome: causes severe valve and heart muscle disease early on, giving a clearly abnormal ECG, and untreated children usually die of heart complications by about 6 to 10 years of age. A normal ECG rules this one out.
2. Hunter syndrome: shares the coarse face, joint stiffness, and delayed development seen in Hurler syndrome, but its heart involvement is milder and slower to develop, so an ECG can still look normal in infancy. It is also X-linked, mostly affecting boys, and generally runs a gentler course than Hurler syndrome.
3. Glycogen storage disorder: for example Pompe disease, causes profound muscle weakness together with a big, failing heart and a grossly abnormal ECG from early infancy, which does not fit a normal ECG.
4. Phenylketonuria: leads to developmental delay and a distinct body odour from a build up of phenylalanine, but it does not cause coarse facial features, joint stiffness, or heart changes, so the clinical picture here does not fit.

Since the heart tracing is normal despite the coarse features and weakness, the milder mucopolysaccharidosis, Hunter syndrome, fits better than Hurler syndrome.

Let's summarize:

• Hurler syndrome causes severe early heart disease with an abnormal ECG; Hunter syndrome is milder on the heart.
• A normal ECG in an infant with coarse features favours Hunter syndrome over Hurler syndrome.

So the likely diagnosis is Hunter syndrome.