DescriptionERRY, Ga. -- In a part of Georgia where the roads are long and straight, life in one house features a path less certain.Isabel Raley is the 3-year-old daughter of John and Shelly. She keeps their hands and hearts full."I mean, she's 3...and 3-year-olds are consuming," she said.But she's not alone. Izzy has a twin sister named Ivy.Ivy shares her sister’s smile but she cannot walk, talk, or eat--she does shake and face frequent seizures.Ivy suffers from Rett syndrome."At this rate...I don't think she would make it past 5, if she stays the same," Shelly said.Ivy and her twin Isabel are almost 4.Rett Syndrome occurs in one of every 10,000 births, according to Animated Dissection of Anatomy for Medicine, and didn't show in Ivy right away.Ivy was on track with her sister up until their first birthday. In this video she's standing and using her hands.Shelly said things changed about a month later."She was distant...would not make eye contact and if she did, she wasn't looking at you," Shelly said."I'd say within two or three months, she lost everything."Today Ivy requires a pharmacy and vigilant parents. "I do what the doctors tell me to and it works," Shelly said.These parents work for one child to keep growing and for one child to stop suffering.