NASHVILLE, Tenn. — A local Nashville family is using their voice to shine a light on a diagnosis so rare it affects an estimated one in one million people.
For Michele Falardeau, a pediatric nurse and mother of three, that statistic is not abstract. It’s personal. Her 9-year-old daughter, Sadie Miller, was diagnosed with a CHD8 gene mutation shortly after her second birthday, a discovery that came only after months of uncertainty, dozens of tests, and a mother’s intuition that something wasn’t quite right.
World Rare Disease Day is on Saturday, February 28, and Michele is sharing Sadie’s story in hopes of raising awareness and support for critical clinical research.
CHD8 is a genetic mutation that affects how proteins are synthesized in the body. According to Michele, the mutation impacts how genetic code is processed, resulting in varying degrees of developmental challenges.
“There’s multiple different forms,” Falardeau said.
In Sadie’s case, her specific mutation causes what Michele describes as “early stop coding.” Which doesn’t allow Sadie to get the full breakdown of code that enables all of her proteins to be synthesized properly.
Because CHD8 mutations can present differently from person to person, the range of severity is wide.
“There’s some people who have it and don’t even know they have it,” Michele said. “And then there’s other people that are affected greatly where they have extreme difficulties with even walking and doing basic life things.”
For Sadie, her mother says, the family considers her “kind of in the middle.”
“She gets to still live this beautiful fulfilling life, and you can just see the drive that she has to want to live and do all these amazing things. It’s so beautiful to watch that,” she added.
However, there are still limitations and difficulties she still has to overcome.
The first signs appeared when Sadie was just four to six months old.
“We started to see some things with her low muscle tone,” she said. “ I’m a pediatric nurse so I just kept watching her. I’m like, ‘She’s not doing the things she should be doing.’”
Doctors initially recommended giving Sadie more time. But as months passed, testing became frequent.
By the time Sadie turned one, she had undergone 72 tests.
“Nothing was pinpointing what it was or what was happening,” Michele said.
The testing was extensive and included blood work, gene mapping, muscle testing, MRIs, CT scans and more, and by the end of it all there were still no clear answers.
“It was endless at that point,” Falardeau admitted.
Emotionally exhausted, the family stepped back from testing for a year.
“Everybody kept telling me there’s something wrong with my child. Yes, I did feel like maybe something wasn’t quite right, but all you see is your beautiful baby,” she said.
When they returned to a neurologist and agreed to full genetic testing, the answer finally came and she received a diagnosis for a CHD8 mutation.
CHD8 mutations are strongly associated with autism spectrum disorder, developmental delays, and low muscle tone.
For Sadie, autism symptoms began to emerge around the time of her official diagnosis.
“We started noticing stimulations. She did a lot of hand flapping and fidgeting with her fingers. She always had this stare that she would do at moving objects. That was probably one of the earliest things that we noticed was her staring at the ceiling fan,” she explained.
Sadie was verbal at age two, however, that slowly drifted as she got older.
“She would say some words and she would repeat things very well,” Michele said. “We were very convinced at one time that she could read when she was at the age of two.”
But over time, she experienced speech regression and is now non-verbal.
Today, Sadie communicates using a speech device.
“She talks to us through this device. She’s still navigating it. She’s still learning, but she spells. She can communicate in a few word sentences with us,” Falardeau said.
The family regularly works closely with speech therapists, occupational therapists, neurologists, behavioral specialists and Applied Behavioral Analysis (ABA) therapists. Orthopedic specialists are also involved due to complications related to low muscle tone.
“She really has a whole team of doctors and specialists behind her.”
While Sadie is currently non-verbal, Michele says there is hope.
“There’s been a lot of studies out there that have shown that some kiddos actually do start having some verbal communication up until age 11 or so. So we are hopeful for that.”
But hope does not mean they haven’t already found a way to live life with Sadie.
“If that doesn’t mean we get to hear that sweet little voice again, that’s okay. We still have other ways of communicating. We love her just the way she is.”
Outside of therapy rooms, Sadie’s two younger brothers play an important role.
“They become very protective of her. They want to help her,” Michele said. “Especially our five-year-old. He just is amazing with her and it’s an absolute beautiful thing to watch.”
Currently, Mount Sinai Health System is conducting research to better understand how CHD8 mutations affect individuals at a molecular level.
The goal: map the gene’s behavior, understand severity variations, and determine possible treatment pathways, and potentially even a cure.
“That research is vital to coming up with a game plan for treatment and potentially cure in the future,” Michele said. “Without that mapping and having that sequencing done, we can’t determine if it’s treatable or not.”
There are emerging conversations in the scientific community about tools like CRISPR gene-editing technology being used in the future, but nothing definitive exists yet.
“This study would help us determine what our next steps could be,” she hopefully said.
Because CHD8 affects approximately one in one million people, researchers face an additional challenge: simply finding patients.
“They don’t know where to send the information either. They don’t know who has this ailment.”
When Sadie was first diagnosed, an online CHD8 family support group had just 99 members.
Five years later, it has grown to nearly 900 families worldwide.
“It’s been amazing to watch,” Falardeau said.
For Michele, rare disease awareness aren’t abstract. Her stepmother also lives with a rare disease.
“It’s just understanding that it is more common than we think it is,” she said. “Rare diseases affect so many people.”
That’s why World Rare Disease Day matters and Falardeau wants you to simply just start the conversation.
“Having that conversation with your neighbor and just sitting down with them and understanding what they might exactly be going through is so important. Because we truly just don’t know,” she added.
Donations supporting CHD8 research are currently directed toward the ongoing study at Mount Sinai Health System. Funds help expand genetic mapping efforts and accelerate research that could one day determine targeted treatments for Sadie and people just like her.
For the Falardeau family, the mission is about more than science. It’s about possibility.
“It’s just time to spread awareness.”
During 2025 World Rare Disease Day, Sadie’s story is a reminder that “rare” does not mean insignificant, and that behind every statistic is a child, a family, and a future worth fighting for.
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