- Scientists are analyzing the genes of a 17-year-old girl who is the size of an infant.
- They hope to find master genes that control development and lead to aging.
- The work might help them slow or stop aging in the rest of us.
A 17-year-old girl with a rare genetic disorder is giving scientists insights into aging that some say could eventually lead to extraordinarily long life spans of hundreds of years or more.
The girl, Brooke Greenberg, stopped growing at 16 pounds and 31 inches long, about the size of a one year old. She babbles when she's happy and cries when she's fussy. She likes to swing and take stroller rides. Despite a history of severe health issues, she can now walk with support.
"Have you ever seen the movie Groundhog Day?" Brooke's mother, Melanie Greenberg of Reisterstown, Md., told Discovery News. "That's Brooke. Every day is the same thing with her. She wears the same clothes she's been wearing for years. She hasn't changed in appearance or size."
Periodically, news reports sensationalize Brooke's story, calling her ageless or frozen in time. But scientists interested in her case are looking beyond sensationalism. They are scanning Brooke's genes for clues about what controls development and causes aging. What they find might eventually help them stop or slow aging in healthy adults.
"If we could identify the locus of her mutation, it gives me and my colleagues the opportunity to manipulate these genes and see if we can sustain youthful vitality, anatomy and physiology for unusually long periods of time," said Richard Walker, a neuroendocrinologist of aging, now retired from the University of South Florida School of Medicine. "These genes are elusive and hard to find. With her mutation, we might be able to do that."
For all the time we spend fighting wrinkles and bald spots, scientists still don't have a full grasp of why and how people age. One theory is that we accumulate damaging genetic mutations over time. Another idea is that genes that are helpful during our youth cause degeneration later in life.
Walker instead suspects that development is programmed into a set of genes, which coordinate the changes that occur from conception through adulthood. The program evolved to get us to reproductive age, he proposes. But there is no off switch. So beyond adulthood, the momentum of development leads to biological erosion and disorder.
So far, scientists haven't found the master genes that coordinate and control this developmental process, but Brooke might provide some clues, suggests a case study published last year in the journal Mechanisms of Aging and Development. In the study, Walker and colleagues found that various systems in Brooke's body are developing at different rates.
Her cells, for example, reflect her real age in the size of their telomeres, which are stretches of DNA at the ends of chromosomes that shorten at a predictable rate over time. Her nails and hair also grow normally. But her brain has not advanced beyond infancy. Her bones are those of a 10 year old. And she still has baby teeth, which resemble those of a first-grader.
"One of the most fascinating things about her is that she really hasn't changed roughly since she was six or seven years old," said her pediatrician Lawrence Pakula, of the Johns Hopkins School of Medicine. "I see her several times a year, and I could not put her pictures in chronological order. I really remain very puzzled by all of this."
Most kids with growth disorders respond to treatments with hormones and other drugs, Pakula said, but those haven't worked for Brooke. That and other details in her medical history suggest that genetic mutations are behind her condition. Walker is now looking for the mutations that have interrupted Brooke's development in such uneven ways.
Finding the source of damage, he hopes, might lead researchers to the master genes that control development. By controlling those genes in early adulthood, instead of in infancy like Brooke, scientists might then be able to preserve a 25-year-old's vitality in people long past retirement age.
"If I am right, we would cease to experience biological aging," Walker said. "We could still die. We just wouldn't get old. The diseases of aging would be avoided. Life span could be extended perhaps more than thousands of years."
"I know this sounds bizarre," he added. "This is science-fictional, but in fact, it's real."
Scientists are indeed making exciting advances in aging research, with insights into calorie restriction, free radicals and other factors, said Jerry Shay, a cell biologist at the University of Texas Southwestern Medical Center in Dallas. But he's not convinced that Brooke's case holds to he key that will unlock all the secrets of old age.
And while he wouldn't be surprised if people some day lived to be 130 or 140, he thinks it's unreasonable to expect life spans of 500 years or more.
"This is an anecdotal and very rare case, and I'm just not sure that, other than a developmental delay, we are going to learn anything from her," Shay said. "We are running into the same error we had with cancer, thinking there is one cause when actually there are 200 causes of cancer. There is not going to be one cause of aging. We are not going to live forever."