The Grammy-winning singer is performing her disco-era hit "I Will Survive" in a tribute to the Bayport girl Friday night at the NYCB Theatre at Westbury.
Marisa, 5, is battling an incurable brain disorder that causes rapid obesity and breathing problems so severe she must rely on a ventilator 24 hours a day. Worldwide, there are only 75 documented cases of the disorder, called ROHHAD.
Gaynor said she read the Sunday story in Newsday about Bill and Danielle Carney's fight to keep their only child alive.
"Her story just tugged at my heart," the singer said in a phone interview Wednesday. "I thought if I could do anything to give her just a few moments of happiness or joy, that I would do that.
"Anyone could relate to the song during any kind of situation they think is insurmountable. She may be too young to understand the lyrics and what survival means, but I know her parents certainly have to think about survival."
Gaynor's manager, Stephanie Gold, of Levittown, forwarded the story to Gaynor. "I haven't stopped thinking about their story since I read it, and I knew Gloria would be touched by it too," Gold said.
Gaynor is active in several charities and recently performed "I Will Survive" for 300 breast cancer survivors at a shopping mall in Houston.
The Carneys said they intend to accept the offer to bring Marisa onstage. Despite her condition, she remains upbeat and active.
"Marisa could use this moment, considering all that she's been going through," Danielle Carney said.
The Carney family and friends have formed a nonprofit, ROHHAD Fight Inc., to raise awareness and money for research. Visit rohhadfight.org or call 516-459-6960.