Which of the following conditions is an established secondary cause of hypertrophic cardiomyopathy (HCM phenocopy)?

Secondary HCM may occur as a consequence of obstructive congenital heart disease, including **critical aortic stenosis** and **coarctation of the aorta**, or an inborn error of metabolism such as **glycogen storage disease**. Acute rheumatic fever is not among the examples provided. **Key takeaway:** In a child with hypertrophy, consider structural obstruction and metabolic disease as secondary associations.\n\n**Glossary:** **Coarctation**: Narrowing of the aorta. **Inborn error of metabolism**: An inherited disorder affecting a biochemical pathway.