By Michelle Durham

PHILADELPHIA (CBS)– Imagine suffering from a neurological condition that robs you of the chance to smile. There are about 1,000 documented cases of Moebius Syndrome diagnosed in the United States. This weekend, there is a convention that is drawing hundreds of people across the country, those who treat these patients and those who suffer from it, to Philadelphia.

“Moebius Syndrome is a rare disorder where babies are born with a lack of facial expression and also inability to move their eyes outward,” explains Dr. Ethlin Jabs.

Reporter: “Do we know what causes this?”

Dr. Jabs: “No we don’t know. But what we do know is that there are probably many different causes. Some of them are environmental and some of them are genetic.”

The only treatment for these patients is an operation to relax their facial muscles; it’s called “smile surgery.” President of the Moebius Syndrome Foundation Vicki McCarrell’s son Sean is affected by it.

“He did not want to have that surgery, but he had lots of speech surgery starting when he was just two and a half,” explains McCarrell.

Sean is now 22 and a Broadcast Journalism Major and is on the radio in Missouri.

The Conference takes place at: Downtown Sheraton Hotel, 17th and Race Streets, Philadelphia.

For more information on Moebius Syndrome visit www.moebiussyndrome.com.