Brooke Greenberg, of Reisterstown, Maryland, died at the age of 20 earlier this month, reports ABC News.  Greenberg was a unique medical case because she never aged.  In all her life, she never developed beyond the physical size of an infant or the mental capacity of a 2-year-old.  Brooke was the daughter of Howard and Melanie Greenberg.  Brooke was one of about a dozen children in the world who have what some call syndrome X, a disorder that prevents them from aging.

In her first six years, Brooke went through a series of medical emergencies from which she recovered, often without explanation. She survived surgery for seven perforated stomach ulcers. She had a brain seizure followed by what was diagnosed as a stroke that, weeks later, had left no apparent damage.  At the age of four, she fell into a lethargy that caused her to sleep for 14 days. Then, doctors diagnosed a brain tumor, and her family prepared to say goodbye.  Suddenly, Brooke opened her eyes and she was fine.  There was no tumor and Brooke continued to live for another 16 years.

According to the New York Daily News, an 8-year-old with a similar condition is being examined as the possible key to eternal youth.  Eight-year-old Gabby Williams weighs only 11 pounds.  Gabby is from Billings, MT and she still looks like an infant and needs to be cared for as if she is a newborn, with her mother and father changing her diapers and feeding her multiple times a day.  Her mother, Mary Margret Williams, said 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.

Gabby’s story was shared in a TLC special in 2011.  Since the airing of the special, scientists have discovered two more people with similar cases of the mysterious syndrome: a 29-year-old Florida man with the appearance of a 10-year-old, and a 31-year-old Brazilian woman who still looks like a toddler.

Scientists believe that the key to the condition may be a gene that slows down developmental inertia.  If researchers were able to identify the gene, they may be able to purposefully slow down development and extend life.  During young adulthood, it may be possible to silence the expression of developmental inertia.  This “on-off switch” for aging would essentially freeze a person at the age at which they change the gene.  At that time, there would be perfect biological homeostasis and the person would become biologically immortal.