Caleb Logan Bratayley, watched by millions on YouTube during his life and livestreamed by his family after his death, mysteriously died last month at the age of 13. Now, the Bratayleys (not their real last name) have released the young entertainer’s cause of death: a congenital, untreatable heart condition.

According to TMZ, the family says doctors told them Caleb’s hypertrophic cardiomyopathy would have been impossible to catch, because he never showed any symptoms. And even if it had been diagnosed, there’s no cure.

TMZ describes hypertrophic cardiomyopathy as a rare condition, but according to the American Heart Association, it’s “very common,” affecting 1 in 500 people. It’s also a common cause of sudden heart attacks in young people.

TMZ says the remaining Bratayley kids, Caleb’s two sisters, have been checked for the condition and told they don’t have it.

The family has continued producing videos for their YouTube reality-lite series since Caleb’s death, adding nearly 30 new videos to their channel. All have view counts in the hundred-thousands, with a handful over one million. You can also buy a limited edition “baked potato” t-shirt, inspired by the late Caleb Logan’s nickname, or a shirt with a cartoon Caleb on it, from the Bratayleys’ YouTube producers, Maker Studios.

The show must go on.

[TMZ.]