Danon disease refers to weakening of the heart and skeletal muscles, along with intellectual disability. It affects men much earlier than women, and the severity is also much more in men. The symptoms of Danon disease usually start surfacing as early as one’s childhood or adolescent years in males. In females, the signs and symptoms mostly start showing in early adulthood. Danon disease life expectancy in men is 19 years, while females affected with this disease can live up to the age of 34 years. While the exact Danon disease prevalence is not known, it is a very rare condition, and as a consequence, not many doctors are aware of its diagnosis.