His mother, Lee, fought a long battle with Huntington's disease, a fatal neurological disorder with no cure.
When the 36-year-old joined the Astros, Smith shared his mom's courageous story with ABC13 and his own fight to fund the battle against HD.
RELATED: After mom diagnosed, Astros' Joe Smith faces 50/50 future with Huntington's disease
Huntington's disease causes the progressive breakdown of nerve cells in the brain.
It deteriorates a person's physical and mental abilities during their adult years, between the ages of 30 to 50 years old.
Smith told ABC13 Sports his mom was "the heart" of the family.
Smith's wife, Allie LaForce, shared a touching message dedicated to Lee saying, "You deserve to be smiling from above... no pain, no struggle, just the greatest happiness and peace in the world. We will be holding your hand forever, mom. We'll never let go."
According to an article on Smith posted on the MLB's website in 2019, Lee was diagnosed in 2012.
Note: Video above is from October, 2019.