Clinical introduction A previously healthy 12-year-old boy presented with chest pain and dyspnoea. ECG (figure 1), echocardiogram (figure 2) and myocardial MRI (figure 3) were performed.

Electromyography revealed mild proximal weakness. Blood tests showed creatine kinase 997 UI/L, aspartate transaminase 398 UI/L, alanine transaminase 293 UI/L and lactate deshidrogenase 1730 UI/L. Ophthalmology test showed diffuse loss of pigment in the retinal pigment epithelium. Myocardial biopsy was performed (figure 4). A cardiomyopathy was suspected. LAMP2 gene was sequenced, and a stop mutation was identified.

Question What is the most likely diagnosis suggested based on the patient’s tests and history?

1. Danon’s disease.

2. Fabry’s disease.

3. Hypertrophic cardiomyopathy.

4. Noonan’s syndrome.

5. Pompe’s disease.