After years of medical struggles and uncertainty, 4-year-old Ailani Troncoso is finally enjoying her childhood, thanks to a special gift from a complete stranger.

Today, Ailani is bursting with energy, but her parents, Amanda and Miguel, remember a very different little girl.

"She was just like a shell of herself. And she just wasn't living," mom Amanda said.

Ailani was born with Alagille syndrome, a rare and catastrophic genetic disorder that was slowly destroying her liver.

"Over time, her jaundice got worse … she had a hard time gaining weight. She was put on a feeding tube. The most discomforting for her the entire time was the itching," Amanda recalled.

The disorder caused bile to build up in her liver, causing relentless itching with little relief. She was too weak to play, too miserable to rest. Doctors at Rady Children's Hospital in San Diego had a sobering message for the Troncoso family: Ailani needed a liver transplant. 

Without one, she was running out of time.

"There was nothing that you could do to help her. It was very emotional. It was very hard," Amanda said. 

Then came a ray of hope – doctors had found a living donor for Ailani.

"We were doing all of the necessities to be on the donor list, and we were just going in for a regular checkup … I just remembered going silent … starting to cry," Amanda said. 

Donor Anh Nguyen, 52, was no stranger to extraordinary generosity.

In 2019, Nguyen's friend Penny Pride needed a kidney transplant. Nguyen didn't hesitate to help. 

"I was in disbelief, absolute disbelief, because who does that? But this amazing human," Pride said. "She's my soul sister."

Few people are called upon to help others as living donors, and fewer still choose to donate more than once. Nguyen did something remarkable, stepping forward a second time to help a child she'd never met. 

"It just, again, stuck in the back of my mind, like, here's someone else that needs help, you know? Is it possible that maybe I could do this again?" Nguyen said.

Her impulse to help runs deep. Fifteen years ago, a traumatic brain injury gave Nguyen a profound understanding of suffering.

"I had migraines every day, all day, for 10 years," Nguyen said. "I just understand what it feels like not to feel well … and to desperately hope that someone or something could help you, you know, and that's why I decided to step forward."

The Troncoso family was emotional as the donated portion of Nguyen's liver arrived in a box.

Nguyen had planned to remain anonymous until a letter arrived from the Troncoso family.

"I just wanted to thank her for everything that she had done, and I hoped that one day that we would meet," Amanda said.

"Amanda wrote this amazing, beautiful, you know, heartwarming letter, and it just touched me. I mean, I cried reading it," Nguyen said.

Care teams at Rady Children's Hospital and UC San Diego Health gathered to watch a now-healthier Ailani ring the bell as they celebrated the gift of life for their young patient. 

"It's exceptionally rare, the courage that it takes to donate a single organ, for most of us, is something that is hard to wrap our minds around … but to come forward and do it again, it's just so profound," said transplant surgeon Dr. Gabriel Schnickel.

"My deepest wish is that more people out there can have someone that can step forward to help them," Nguyen shared.