New Jersey Dad Donates Kidney – and Plans to Donate Part of His Liver – to Ailing 2-Year-Old Daughter: 'I Would Give Her All My Organs If It Helped'

Paul Rybkin and Karen Rodas knew the challenges ahead of them when they discovered their baby had a rare genetic disorder – but they were ready to face them.

The Saddlebrook, New Jersey, couple's 2-year-old daughter Madeline has autosomal recessive polycystic kidney disease (ARPKD). The disorder, which results in the deterioration of kidney and liver function, can be fatal.

The couple's first child, Nathaniel, died from the same condition just 36 hours after his birth in 2012 – but it's not a "death sentence," Karen says.

"The kidneys form large, water-filled cysts, and these cysts start to prevent the kidney from working normally," Karen tells PEOPLE. "They become really enlarged and the function decreases because of these cysts. The kidneys control a whole slew of things, so these cysts start to interfere with that."

Both Karen and Paul, who have been together for five years, carry the recessive gene that causes ARPKD, which ultimately occurs in 1 in 20,000 individuals, according to the PKD foundation. Despite knowing that they had a 1 in 4 chance of passing it on to their children, they still opted against doctors' suggestions to terminate their pregnancy at 20 weeks.

"We thought our chances were good that our next baby would be healthy," says Karen, who owns a deli with Paul.

A Devastating Diagnosis

Madeline was born prematurely at the Children's Hospital of Philadelphia on November 7, 2013, and was immediately hooked to a ventilator to help her lung tissue development. Karen says that she and Paul, both 38, knew early on that their daughter would eventually need a transplant.

"It was not a matter of if, it was a matter of when," she says.

Both parents were immediately tested and Paul ended up being a perfect match for Madeline.

"I decided if I was a match, in a heartbeat I would donate with no questions asked," Paul tells PEOPLE. "It was one of the happiest moments of my life – there are so many people out there that suffer and wait for a transplant, and they suffer the entire time they are waiting."

As the concerned parents watched their daughter get sicker, they were devastated when doctors told them they had to wait for the transplant procedure.

"We had to watch her get worse before we could watch her get better," Karen says, noting that because Madeline's kidneys still functioned, and she was just a baby, an invasive surgery would be dangerous.

Madeline continued to grow – as did her kidneys. And at 6 pounds, 3 ounces each, they ballooned to nearly triple the size of a normal adult's kidneys.

"She had trouble breathing, she had trouble eating, she was just very tired all the time – she struggled doing basic things like sitting up," Karen remembers. "We had to watch her not do well, and not be a normal baby."

Adds Paul, "Madeline has been through a lot and she's been through more than any individual should have to go through – let alone somebody under the age of 2."

Preparing for the Transplant

Madeline could barely eat, and she threw up almost every night. It was then that Karen and Paul decided to get a second opinion. The couple met with Ron Shapiro, surgical director of the Kidney and Pancreas Transplant Program at Mount Sinai's Recanati/Miller Transplantation Institute in the summer of 2015, and after a few months of testing, Madeline's transplant was scheduled for January 19.

By the time the surgery rolled around, however, Madeline had grown so sick that she had to be on emergency dialysis.

"It was terrible, I hated it. Thinking about it now – she wasn't really living her life, she was just kind of existing," Karen says through tears. "Madeline was always happy, as sick as she felt through everything, she always smiled."

The surgery – performed by Dr. Shapiro and Dr. Scott Ames – was a success, and while Paul had a painful recovery, Madeline did beautifully.

"She is a completely different child. It's like a light went on," Karen says. "She wants to move, and she's got energy, and now she fights it when you put her down for a nap. She laughs, and laughs and laughs," she adds.

Paul says Madeline is "obsessed" with the Cookie Monster and loves going to the park just to sniff the flowers with her "daddy."

"Flowers are her favorite things, I bring her some after I come home from work every day," says Paul through tears. "We don't allow much time to pass without spending time together."

The Long Road to Recovery

Madeline isn't completely out of the woods, however. While the toddler hasn't had any issues with her new kidney, she's had a few unrelated infections that are more dangerous due to her suppressed immune system. She'll take immunosuppressants for the rest of her life, and will always face the chance of rejection. Dr. Shapiro also says that it's hard to pinpoint an exact expiration date for Madeline's kidney, but noted that it could last between 10 and 20 years. "Oddly enough, if you look at small kids getting kidneys from parents, they tend to do exceptionally well, so this kidney may last longer," he explains.

In addition, Madeline's liver has some thickening, a sign of cirrhosis. She will eventually need a transplant.

"We found out that I can donate part of mine to her when that time comes," Paul says. "I would do that without blinking. We went through the compatibility test and are all set. I'm expecting to and I would give her all my organs if it helped."

While Paul manages the family's deli, Karen devotes all of her time to care for Madeline, something Dr. Shapiro applauds. "It's of enormous importance having a parent who is so skilled at taking care of their child," he says. "Taking your medications perfectly all the time, forever, is the whole show. Karen is really with the program, and it makes a huge difference."

The couple hopes to offset some of their steep medical costs through a YouCaring crowdfunding campaign.

Paul and Karen are also balancing being parents to two children under three. Karen and Paul welcomed a second daughter, Penelope, in January 2015. Karen says that when she unexpectedly got pregnant, she and Paul were concerned about the baby being born with ARPKD.

Karen's pregnancy was closely monitored, and at around 20 weeks, Penelope was deemed ARPKD-free. Karen says her doctors were cautiously optimistic, and after the baby's birth, an ultrasound showed she was perfectly healthy. Karen's older son Jackson, 9, (from a previous marriage) was also born without ARPKD.

Paul and Karen are now settling into life as a family of five – and they're grateful for Madeline's improved health.

• Need a little inspiration? Click here to subscribe to the Daily Smile Newsletter for uplifting, feel-good stories that brighten up your inbox.

"I don't think I did anything any other parent wouldn't do given the opportunity," Paul says. "Knowing it was successful was the best feeling I've ever had. I saved her life – that's the bottom line. It's a feeling that's difficult to describe – knowing that I was able to give her a second chance at life."

And at just 2 years old, Madeline knows about her dad's sacrifice. "She loves her daddy, they have a special bond," Karen says. "If we say the word 'Dada,' she pats her belly… she understands more than we give her credit for."

"I can't put into words how much I feel for her," Paul says. "She's daddy's little girl. We're best buddies."

• Reporting by ROSE MINUTAGLIO