Deondra Dixon and Jamie Foxx
11/03/2011 at 04:55 PM EDT
She has appeared in her brother Jamie Foxx's "Blame It" music video, hit the stage at the 52nd Annual Grammy Awards in front of 26 million viewers and "battle danced" with celeb pals such as Denzel Washington and Chris Brown.
But DeOndra Dixon's latest turn in the spotlight makes her brother especially proud: The outgoing 27-year-old is the 2011 Ambassador for the Global Down Syndrome Foundation.
"She's a superstar now," Foxx, 43, tells PEOPLE in an exclusive interview in this week's issue.
"One thing people may not understand is that the love a person with special needs gives you is unfiltered," he says of their strong sibling bond.
"There is nothing in the way of them loving you and there is nothing in the way of them being upset with you either. You really get the true individual."
As for DeOndra, who lives with Foxx in Los Angeles, she is grateful for her Oscar-winning brother's support. "I'm happy to have a big brother to count on, who I love every day," she says.
For more on Jamie and DeOndra, pick up this week's issue of PEOPLE. Click here for more information on the Global Down Syndrome Foundation