CHICAGO (WLS) -- An 11-year-old boy from Mississippi with a rare condition is living beyond expectations with help from a specialist in Chicago. He attended a doctor's appointment at Lurie Children's Hospital on Tuesday.Levi Krystosek is shorter than most children his age due to a condition called Jansen's syndrome, which causes his bones to not form properly.Levi was told he wouldn't walk, but thanks to a specialist in Chicago, Levi is living beyond anyone's expectations."I think he's doing phenomenal, most of the kids his age and older are wheelchair bound, they're horribly crippled, and he certainly is not that," said Dr. Craig Langman."They're saying you're not going to do this, you're not going to be able to do that...just tune them out, do what you feel like you can do," said Levi.Since he was a baby, Levi has been travelling to Lurie Children's Hospital from Mississippi to see pediatric kidney specialist Dr. Langman. Because Levi started treatment when he was a baby, he is quite mobile."We were coming up here every six to eight weeks, we depleted our savings account, we maxed out our credit cards...we knew where we had to get him, but we didn't know how we were going to get him there," said Dona Krystosek, his mother.Levi and his mother get to Lurie's thanks to Miracle Flights, and recent grants from Astellas USA Foundation.