ATLANTA - At 17, Liam Nelson of Atlanta has grown used to strangers stopping him to tell him how tall he is.
And he is tall -- 7 feet tall, to be exact.
"The real awakening came when I hit 6' 8," and I started hitting my head on doorways," Nelson laughs.
But, the Galloway School senior and budding filmmaker isn't self-conscious about his height.
"Being 7-feet tall, that could be something that makes you shrink into yourself, and feel awkward, and depressed about it," says Kelly Nelson, Liam's mother. "He's just used it."
Still, as a young child, Kelly Nelson says Liam was growing so quickly, his doctor became concerned.
"Our pediatrician noticed it at about 5, 6, 7 years old," she says.
The doctor suspected Liam might have Marfan syndrome, a potentially life-threatening genetic disorder that affects the body's connective tissues.
The Marfan Foundation says some common signs are a tall, thin body type, long arms, legs and fingers, a curved spine and chest that sinks in or protrudes out.
Liam has other common symptoms: vision problems, crowded teeth, flexible joints and stretch marks that aren't caused by weight gain or loss.
In early elementary school, he was sent to a geneticist for an evaluation, but he was not diagnosed until years later, he was 11.
"It's kind of a hard thing to come to terms with," Nelson remembers. "For about a year, I didn't really understand how severe of a thing it was for me to have."
Researching Marfan syndrome online, Nelson learned the disorder affects everyone differently.
Some people have problems with their heart and blood vessels, bones and joints. Others may have issues with their lungs, eyes and nervous systems.
Nelson was most alarmed by why Marfan syndrome could do to his heart.
"Like, I was sure I was going to die before I was 30," he says.
At Children's Healthcare of Atlanta Sibley Heart Center cardiologist Dr. Glen Iannucci says some people Marfan syndrome have a weakened or enlarged aorta, the main blood vessel carrying blood from the heart to the rest of the body.
If it ruptures or tears, Iannucci says, it can be deadly.
"In many cases, patients don't have a lot of symptoms related to their heart until there is a sudden event," he says.
Liam is on medication for his aorta, and has had 3 surgeries, on his knees, legs and chest.
But he feels lucky.
Half of people with Marfan syndrome aren't aware they have the disorder.
If those people can be identified before they get into an emergency situation, it's a condition we can manage and take care of," says Dr. Iannucci.
Along the way, Liam Nelson began to realize he's not alone.
Two years ago, he started going to the Marfan Foundation's yearly conference, where he met hundreds of people just like him, living with Marfan syndrome.
"Some of them are in their seventies," Nelson says. "People who have made things of their life, despite having Marfan, they've gone out and done things that are incredible."
He's now working on a documentary to tell their stories.
"(I want) to show them that no, you have a future," Liam Nelson says.
"You can do what you're passionate about."
If you suspect you or someone you know might have Marfan syndrome,
you can find more information on what to do on The Marfan Foundation's website, https://www.marfan.org/if-you-suspect.