8-Year-Old Never Ages: TLC TV Show Searches for Secret to 'Biological Immortality' (VIDEO)

An 8-year-old who never ages and still weighs just 11 pounds could reveal the secrets to biological immortality, according to doctors and researchers.

(Photo: ABC News/TLC Screen Shot)8-year-old, Gabby Williams, never ages.

Gabby Williams still has the features and looks of a newborn, and is as dependent on her parents as the day she born. The little girl has a rare condition that only a handful of others throughout the world are known to have had; the condition slows down her rate of aging, keeping her seemingly frozen in time and barely growing.

One doctor, who has spent the past two years investigating whether there is a so-called "genetic off-switch" that will halt the aging process in humans, is studying Gabby and two others with similar conditions.

One of those is a 29-year-old Florida man, who remains in the body of a 10-year-old, as well as a 31-year-old Brazilian woman, who remains the size of a 2-year-old.

The three seem to be connected by the similar condition that has stopped them aging, and researchers are attempting to find what the three have in common that could be connection and key to halt aging.

All three will be featured in a TLC television special, "40-Year-Old Child: A New Case," which airs Monday, Aug. 19, at 10 p.m. ET.

Medical researcher Richard F. Walker has said, "In some people, something happens to them and the development process is retarded. The rate of change in the body slows and is negligible."

"My whole career has been focused on the aging process," he told ABC News. "My fixation has been not on the consequences but the cause of it."

Gabby's mom has said that she "hasn't changed since pretty much forever. She has gotten a little longer and we have jumped into putting her in size 3-6 month clothes instead of 0-3 months for the footies."

"Last time we weighed her she was up a pound to 11 pounds and she's gotten a few more haircuts."