Summary: This is a non-randomized open-label Phase 1 study to evaluate the safety and toxicity of gene therapy using a recombinant adeno-associated virus serotype 9 (AAV9) containing the human lysosome-associated membrane protein 2 isoform B (LAMP2B) transgene (investigational product (IP), RP-A501) in male patients with Danon Disease (DD).

Summary: Danon disease (DD) is a rare, X-linked disorder associated with severe cardiomyopathy, and in many cases, skeletal myopathy, and cognitive impairment caused by mutations in the LAMP2 gene. There is still uncertainty regarding the natural history of DD because of its rarity.This study aims to determine the natural history of DD through the collection and analysis of retrospective and prospective da...