40-Year-Old Child will look into the medical mystery of the rare condition that causes slowed-down aging.  Eight-year-old Gabby Williams weighs only 11 pounds.

A girl from Billings, Mont., looks like an infant and needs full caring as if she is a newborn. Her mother and father change her diapers and feeding her multiple times a day.

Her mother, Mary Margret Williams, told that Gabby hasn’t changed much over the years. In fact, her skin still feels like a baby’s and her hair is still fine-textured.

“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,” she said.

She is one of just a handful of people in the world with a rare condition that slows the aging process. Medical researcher Richard F. Walker has been studying Gabby for two years. His particular interest is investigating the cause of slow aging.

“In some people, something happens to them and the development process is retarded,” he said. “The rate of change in the body slows and is negligible.”

Gabby appears with two others who share her condition: a 29-year-old American with the body of a 10-year-old, and a 31-year-old Brazilian woman who’s two-year-old girl.

Walker suspects that Gabby and the others may have a genetic impairment that interferes with a crucial process called “developmental inertia” that affects growth in humans.