Booker said in a press release:
"I've celebrated the accomplishments and witnessed the challenges my sister Mya has experienced as a person with intellectual disabilities. She motivates me every day, and I'm humbled to be part of Special Olympics, a global organization with a mission to help spread awareness about the abilities of people with intellectual disabilities."
Booker's sister, Mya, has 22q11.2 deletion syndrome, which causes "poor development of several body systems, which can result in mild to moderate intellectual disabilities," according to the Special Olympics release.
Booker has been involved with Special Olympics Arizona since 2015. He invited Jenna Warren and Noah Smith to accompany him to the draft lottery in 2016 and 2017, respectively. Special Olympics Arizona is also one of five organizations Booker selected as part of his Devin Booker Starting 5 initiative, which donates $500,000 per year to charities.
Other NBA players who serve as Special Olympics global ambassadors include Damian Lillard, Andre Drummond and Rubio. Past standouts Dikembe Mutombo, Sam Perkins and Yao Ming also help with the organization.