After tests, she was diagnosed with Rett Syndrome, a debilitating autism disorder which most often strikes previously healthy little girls just after they have learned to walk and say a few words and begins to drag their development backwards.
Her father Marc said Dylan was born in July 2009 and by the time she was one had learned to crawl and say a few words and was poised to start walking.
"She was like any other little girl," he says.
"She was hitting all her milestones and crawling around making a nuisance of herself pulling things off surfaces."
But then Dylan's development faltered before going into reverse. Marc and wife Jenny, 36, could only watch as she became confused and withdrawn.
She stopped crawling and suffered from terrible headaches and muscular pain.
"We were told not to worry at first but I could see she was losing lots of skills," Marc, 36, says.
"The last time she said Da Da she was 14 months old. She hasn't spoken since."
Shortly after her second birthday a genetic test revealed Dylan had Rett Syndrome - a severe autism spectrum disorder that affects roughly one in 10,000 girls.
It is caused by mutations in the gene MECP2 found on the X chromosome. While boys with the disease only survive a few weeks, most girls with the condition only start displaying symptoms after their first year.
But now scientists from the University of Virginia School of Medicine in Charlottesville, U.S, have made a breakthrough that could combat the devastating condition using bone marrow transplants.
"It's such a horrible, brutal condition so the fact there could be a potential treatment fills us with a mixture of hope and elation," Marc said.
Scientists, speculated that the brain-dwelling immune cells called microglia are defective in those with the syndrome.
"We know it's not a cure but at last we can see a path for clinical treatment," Marc said.
"Dylan's future is so bleak and we would do anything if it would help her. "Dylan is a real fighter. Every day she is trying so hard."
• For more information on Dylan's condition visit www.curefordylan.com