"I think it's significant because you train really hard, you work really hard to run a marathon and people with Down syndrome, they work very, very hard just to have the same things that everybody else has," Brown said. "To me, having a child with Down syndrome is a lot like running a marathon. It's mostly fun, it's mostly beautiful, but there are some miles that are a struggle. You kind of push through them to get to the finish line, and the finish line is always that next goal."
Brown is a mom to three children. Her middle son, Will, 3, has Down syndrome.
Will will be one of the 26 people whom Brown is running for during the marathon.
"Having Will opened up my eyes to a population of people I had no previous experience with," Brown said. "I realized that people with Down syndrome are just like everyone else. They have the same feelings, the same capacity for love. They have a much higher emotional intelligence than the average person. Will works so hard for the same things that come easily to others.
"I’m not trying to do anything except show the world that people with Down syndrome are just like them," she added. "I’m not trying to change laws or do anything really spectacular. I just want people to see Will for Will -- an adorable, clever, funny little boy who is loved tremendously."
One year ago, Brown had the idea to raise money in honor of the LuMind Research Down Syndrome Foundation by dedicating each of the 26 New York City Marathon miles to 26 different people with Down syndrome.
LuMind is a nonprofit organization that funds research to support advances to improve memory, cognition, and independence in individuals with Down syndrome.
For the fundraiser, Brown suggested a donation of $321. That $321 would represent the third extra copy of chromosome 21 that people with Down syndrome possess.
She brought the idea to LuMind and within three weeks, she raised more than $8,500 on their crowdfunding page in October, during Down syndrome Awareness Month.
The first 26 people to donate $321 or more received a mile to devote to a loved one with Down syndrome.
The final, 26th mile is dedicated to Karen Gaffney of Portland, Oregon.
Gaffney is president of is the Karen Gaffney Foundation, an organization which supports full inclusion for people with Down syndrome and other disabilities.
“I have Down syndrome, and I try to help people see that Down syndrome is a life worth living," Gaffney told ABC News. "We have to work much harder than anyone else, but we can do it! We need help being able to think better, think more clearly to keep up with everything that is going on around us. We are getting stronger all the time, but having better medical research to improve our lives, not prevent them, is something we really need.”
Ellie Bowerman, who just turned 8 years old, has mile 17 with her name on it.
“[W]e asked she what she wanted to be when she grows up, and she answered, ‘a super hero,’" said dad Bret Bowerman of Larchmont, N.Y. "Based on the level of work she puts into everything she does, I have no doubt she can achieve to which she sets her mind.”
Brown will interchange five to six shirts at a time, peeling one off as each mile passes. Representatives from LuMind will be standing at various predetermined points of the race with T-shirts in-hand, so Brown can showcase the name that is printed on each of the 26 shirts.
A number of families will stand at their designated mile, cheering on as Brown runs by -- including her own family at mile 18.
For the final .2 miles of the 26.2-mile race, Brown will wear the T-shirt with her son's name to cross the finish line.