THE GIGGLE is worth it all.

That's what Mari-Carmen Farmer might have told Mine Ener if she'd gotten to meet her.

Ener is the Villanova professor who gave birth in February to a baby with Down syndrome - then murdered the baby in August because, she told police, she "didn't want her to go through life suffering."

Soon after, Ener committed suicide in a Minnesota prison.

Mari-Carmen Farmer is the mother of a disabled 2-year-old, Caela, who cannot stand, swallow or speak - but whose giggle can melt your heart.

A mutual friend of both women thought Farmer might have encouraging words to share with Ener about raising a fragile child. She hoped Ener might even attend a fund-raiser for Caela this Sunday. There, she would see that there is a world of big-hearted people waiting to lend a hand through the tough times.

But Ener never responded to Farmer's e-mail of introduction. And the rest is tragic history.

"I wonder, if we'd had a chance to meet, if things might've gone differently," said Farmer, 34, who lives in Wynnefield with husband Tatum, 29, Caela and kids Daniel, 8, and Joycelin, 3.

"I would've told her that life with a disabled child is challenging, but amazing support is out there. Incredible people are in our lives, because of Caela. She's blessed us."

The Farmers use the word "blessed" so often when speaking of Caela, it can make you think they've been spared the burdens of raising a special-needs child that apparently seemed so insurmountable to Ener. You'd be wrong.

Caela, whose disability remains undiagnosed despite every fact-finding test known to medicine, is delayed in every way. Tiny for her age, she lacks gross- and fine-motor skills, cannot speak, is fed through a tube and has seizures. She communicates only through her eyes - enormous brown orbs fringed by thick lashes.

"They just pull you in," said speech and language pathologist Daniele Modica, one of a team of therapists who help the Farmers provide Caela's care, 24/7. "Her spirit shines through her eyes."

Still, a feisty spirit alone isn't always enough to help a disabled child's family adjust to the shock of their situation.

"It can be devastating," when a child is born profoundly disabled, said Nancy Teichman, CEO of Easter Seals of Eastern Pennsylvania. "They must become experts in a disease they may never have heard of. No one takes them by the hand and says, 'OK, here's what you need to do and here's how to do it.' Their world changes forever."

Tatum, a network administrator for Independence Blue Cross, and Mari-Carmen, a sociologist, had thought they had that world on a string.

They had two healthy children, good jobs, a nice income, exceptional insurance and strong family and community ties. After Caela was born, Mari-Carmen planned to go back to work as a service-learning coordinator for city and suburban high schools.

Within days of Caela's birth, though, they noticed she was eerily quiet and still. Over the next months, she was hospitalized for weeks as doctors tried to learn why she was failing to add weight to her tiny frame.

Since then, it has been a roller-coaster as Caela's condition has alternated between heartening medical gains and heartbreaking setbacks, punctuated by long hospital stays and all-too frequent visits to a host of medical specialists.

Through it all, the experts have been awed by how seamlessly Tatum and Mari-Carmen, who now cares full-time for Calea, have adjusted to her constant, complex needs.

"From day one, they've accepted her exactly as she is," said Modica. "Some families with disabled children are very specific about the gains they want their child to make. They say, 'I want my child to walk, talk, ask for juice.' The Farmers say, 'We want Caela to be part of our lives, on her own terms. And we will do whatever it takes for that to happen.' They're very relaxed about it, but determined. I think that's why they're not stuck in the grieving that some families get into when their child has a disability."

Adds Caela's pediatrician, Theodore Tapper, "They are a remarkable family - heroic."

And yet it is not enough.

As Caela grows, she'll need much that insurance won't cover: A special bath chair. A wheelchair, with a lift - and a retrofitted house to accommodate it. Pricey computer software that will help her communicate with more than her eyes. New and expensive medical opinions.

That the Farmers may not be able to provide this to Caela is unacceptable to Modica. Along with other fans of the Farmers, she is hosting a massive fund-raiser, called Fund-Fest, this Sunday at Carousel House, the Fairmount Park recreation center for people with disabilities.

Modica's big Italian family is making the food. Stores and travel agencies are donating a raft of raffle and auction items. The kids' entertainment is gratis.

All of it is designed to raise money - and to let the Farmers know they are not alone on their journey.

The guest of honor will be Caela, listening for a sneeze.

"For some reason, when someone sneezes, she cracks up," said Mari-Carmen. "It takes a lot of exertion for her to laugh, so we rarely hear her giggle. When she does, we go crazy with joy."

A giggle. Such a small thing.

If Mine Ener had had a chance to hear it, would it have made a difference?

For more information about Caela's fund-raiser, go to www.brightfuturefund.org, the Web site her family has created to tell her story.