Danon Disease: A Challenging Case with Diagnosis of Hypertrophic Cardiomyopathy

Danon disease is an X-linked dominant glycogen storage disease characterized by cardiomyopathy, skeletal myopathy, and intellectual disability. Danon disease has a rapidly progressive natural course, hence early diagnosis is crucial to achieve a proper management plan. This case concerns a 30-year-old male of Danon disease presenting with symptoms and signs of systolic heart failure, with no intellectual impairment and skeletal muscle involvement at presentation. Thus, he was initially misdiagnosed and managed as idiopathic sarcomeric hypertrophic cardiomyopathy. To the best of our knowledge, this is the first report of Danon disease in Iran, further implicating previous cases overlooked by local cardiologists.