The niece of Toni Braxton, Lauren Braxton, died at 24

EXCLUSIVE

Toni BraxtonThe niece is dead in Maryland … TMZ has learned.

Lauren Braxton – the daughter of Toni's younger brother, Michael Conrad Braxton Jr. – died Monday … according to his father, who tells us that his death was related to heart disease.

The security forces told TMZ … that they received a 911 call around noon on Monday, and Lauren, nicknamed LoLo, did not respond to their arrival. She was declared dead by paramedics.

Michael – who is from Maryland – is the only son of Braxton brothers and sisters. He and Toni are the older siblings of Traci, Towanda, Trina and Tamar. Like most of his sisters, Michael is also a singer and songwriter. He appeared in episodes of his sisters' reality show titled "Braxton Family Values".

Michael started singing with his sisters in church choirs when they were young.

His daughter Lauren was 24 years old.

TEAR