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A small gold charm hangs from Jordana Holovach's neck. It's about the size of a thumb print and says "smile."

It is a symbol of her 9-year-old son, Jacob. Diagnosed with a rare genetic ailment, Canavan disease, Jacob is wheelchair-bound and cannot hold up his head. But boy, the kid can grin.

"He communicates with his smile," she said. "He doesn't want you to forget he's right there in the room with you, listening to you, and his smile shows you that."

Proceeds from the charm benefit Holovach's nonprofit (see a flash presentation here: http://asap.ap.org/data/interactives/_lifestyles/jacobs_cure/ ). But it must compete with a rather large box of jewelery inspired by disease. It was designed by Helen Ficalora, who has done many charity pieces, including a breast cancer ribbon charm and a tulip charm for ovarian cancer with Jennifer Garner.

These days, it's hip to wear celebrity-designed charms, or yellow "Live Strong" bracelets to support Lance Armstrong's foundation. A rainbow of knockoffs have surfaced for other diseases.

Some are just reminders: pink and red ribbons, a guardian angel amulet in your pocket. And others profess to help heal: some think copper bracelets to help with arthritis and Tiger's eye is supposed to help blood pressure.

The idea has been around for ages, rooted in amulets and talisman worn in ancient times to ward off evil or to cure disease.

"We don't really know the origins," Terry Wilfong, Egyptologist at the University of Michigan. "Some of the earliest Egyptian material could be considered amulets, which they wore for protection."

Amulets and talismans (now called charms) were once thought to hold special powers for the wearer. The objects were worn around the neck or ankle or in some other way carried on the body. They warded off illness, offered protection from the gods and aided in fertility -- or so thought many ancient civilizations, and even recent cultures.

"Egyptians wore a lot of multipurpose amulets," Wilfong said. "The great majority of the people were poor, and if you were going to make an investment in an amulet, it better be one that does a lot."

The Egyptian ankh symbol for life was a good example and it's still worn today. A representation of the god Horus as an eye might have been worn to protect against eye disease. Plus, Wilfong said, it's always good to have a god on your side. They sometimes wore representation of body parts, little feet or little hands, which may have been an attempt to cure arthritis.

In later times, silver amulets were engraved to aid in digestion and for hip aches. Others were made out of a red stone, which was considered especially protective.

"Infant mortality and morality of women in childbearing years was high in ancient Egypt. So a large number of mothers wore these to protect themselves and their children," Wilfong said.

In the early 20th century, Arabic amulets were used to cure cough, to prolong life and ward off evil spirits. They were made from bamboo, snake skin and knives, and appear more rudimentary than their earlier Egyptian counterparts.

"It's hard to say how much people believed in these things," Wilfong said. "They're around still, so they must have some sort of function. In Egypt, where life was rough, it couldn't hurt to own something that perhaps offered special protection, something that related to their lives."

For Ficalora, the idea makes sense. She designed the breast cancer charm because her mother died of the disease.

"I like my jewelry to mean something, I like to have a connection to it," Ficalora said, standing behind the counter in her new shop in New York City. She doesn't want to be known as the go-to girl for charity charms, but she's always interested in helping people out.

"The love energy that's put together with a piece stays with the piece," she said. "That's why people give engagement rings, why they give jewelry. It has that ancient connection."

Holovach knows her smile charm alone isn't going to help find a cure for Jacob's disease. But she hopes the representation will serve as a reminder, and frankly, help out her nonprofit.

"We live in a society where people think, 'If it's not happening to me than it must not really be happening,'" she said. "I'm hoping that people will realize the little-known diseases will help cure the larger ones. If we figure out how to help my son, we can figure out how to help others."