The cause of death for YouTube star Caleb Logan Bratayley is still undetermined. His parents, however, shed a little light into the family’s history of heart disease, specifically “hypertrophic cardiomyopathy,” in an interview with ABC's "Good Morning America" Tuesday.

The disease is described as a condition where the heart muscle "becomes abnormally thick," the Mayo Clinic explains. “The thickened heart muscle can make it harder for the heart to pump blood."

It can go undetected since those who suffer with it "have few, if any, symptoms.” In some cases, people “can lead normal lives with no significant problems.” The small number of people who do experience symptoms of HCM can experience “shortness of breath, chest pain or problems in the heart's electrical system,” the Mayo Clinic said.

The Bratayleys have been open about Caleb’s death on social media. He was 13 when he died Thursday from “natural causes,” the family wrote on Instagram Friday, a day after his untimely death. His family wrote an updated Instagram post Monday: "Tests have confirmed today that Caleb passed away from an undetected medical condition. We'll have more definitive answers in the coming weeks but ask that you help us celebrate his life instead of focus on his death."

Heart disease was one of the factors that could have contributed to Caleb’s tragic death at such a young age, Dr. Bruce Lee told Hollywood Life in an exclusive report Monday. “The most common causes of death, in order, between the ages of 10 and 14 are: accident, cancer, suicide, homicide, congenital anomalies (birth defects) and heart disease, mainly cardiac arrhythmia,” he said.

Caleb’s cousin David Cooper hanged himself at the age of 10, People magazine reported Monday, but sources said Caleb’s death was not a suicide. Drugs also were not involved in his death, sources told TMZ.

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