A month after 13-year-old YouTube star Caleb Logan Bratayley's shocking death, doctors have established cause of death as a heart condition called hypertrophic cardiomyopathy, according to his family.

"Caleb didn't have any symptoms, so the doctor said there was nothing we could have done differently," his family posted to Instagram on Tuesday. "The girls' hearts were just recently checked and thankfully look the way they should right now. The sadness of losing someone you love is unimaginable. Thank you to everyone who has reached out, your kindness and support continues to help our family. We miss our baked potato everyday.#calebratelife"

WATCH: Caleb Logan Bratayley's Parents Reveal He Died of 'Undetected Medical Condition'

Hypertrophic cardiomyopathy is an incurable condition in which the heart muscle becomes abnormally thick. Symptoms include shortness of breath, chest pain and abnormal heart rhythms, but most people with the condition never experience symptoms or significant problems at all.

The Bratayleys previously shared that Caleb died of "an undetected medical condition" after police in Anne Arundel County, Maryland, responded to a call at his family's home on Oct. 1.

WATCH: YouTube Star Caleb Logan Bratayley Dies at 13

On Oct. 4, the family posted a video in remembrance of the YouTube star, who did an online show affiliated with Disney's Maker Studios with his two younger sisters, Annie and Hayley.

"Words cannot describe how much we will miss him," the video description reads. "His incredibly funny, loving and wonderful spirit made us all fall in love with him as a YouTuber, friend, brother and son."