3 years ago, Christina Applegate was diagnosed with MS. Now her daughter has her own health battle.

When Christina Applegate received her star on the Hollywood Walk of Fame in November 2022, there was one person in particular that she dedicated her award to.

It was her only child, daughter Sadie Grace LeNoble.

"The most important person in this world is my daughter. You are so much more than even you know," she said to Sadie, who was sitting in the audience. 

"You are so beautiful and kind and loving and smart and interesting, and I am blessed every day that I get to wake up and take you to your school. You are my everything. Thank you for standing beside me through all of this." 

The pair have a particularly close mother-daughter relationship, especially given Applegate's health struggles with multiple sclerosis.

Watch: Selma Blair on her struggles with multiple sclerosis. Post continues below. 

Earlier this month, Applegate opened up about the hardship of losing her mobility because of the debilitating disease.

"I'm in a depression right now, which I don't think I've felt that for years," she said on her podcast MeSsy. 

"Like a real, f**k-it-all depression where it's kind of scaring me, too, a little bit because it feels really fatalistic. I'm trapped in, like, this darkness right now that I haven't felt [in], like, I don't even know how long, probably 20-something years."

But throughout it all, her daughter Sadie has been right by her side. 

Here's everything we know about Applegate and her only child.

Who is Christina Applegate's daughter?

Applegate welcomed daughter Sadie Grace LeNoble with her now husband, Martyn LeNoble, in 2011. Applegate and LeNoble then married in 2013 and have remained together since.

Applegate has previously said that becoming a mother filled her with a "level of love" that was overwhelming.

"I love my kid … more than I've ever known is possible. Like, humanly possible. It's a spiritual thing … I really love her," she shared with PEOPLE in 2020.

Now aged 13, Sadie is well-versed in the Hollywood arena. She was exposed to the world of television and film from a young age, Applegate saying she regularly brought her daughter on sets with her. 

"My whole thing was, 'I'm not doing this unless I can bring her.' So they had to build me a room for her and it's got her toys and a crib and she takes her naps there," Applegate explained. "That's called a crazy mother who said, 'No, I'm not doing anything unless I can be with my baby.'"

The pair have recently attended multiple events together, Sadie assisting her mother with her mobility.

In February 2024, Sadie was Applegate's date to the SAG Awards, where Applegate had been nominated for Outstanding Performance by a Female Actor in a Comedy Series in Dead to Me.

They walked the red carpet together, Applegate using a cane that read "FU MS."

At the time, she said it would be her "last awards show" as an actor.

Christina Applegate's daughter Sadie on her own health challenges.

Sadie appeared on her mother's podcast this week, also co-hosted by American actor Jamie-Lynn Sigler. During the episode, she revealed her own challenging health diagnosis.

"Last year, in sixth grade, I would go to the nurse multiple times for it because I always felt like I was going to pass out," Sadie explained. 

"When I stand up, I get really, really dizzy and my legs get really weak and I feel like I'm going to pass out and I have fainted before and I have gone unconscious."

Although Sadie would tell the nurses at school her concerns, she felt her symptoms were often dismissed.

"They were like, 'You're doing this to get out of class. It's probably just anxiety. Go back to class,'" she said on MeSsy.

"I genuinely felt so sick and I was in a lot of pain and them not doing anything about it definitely hurt me physically and emotionally because I was just like, 'This is rude. I feel sick and you are telling me to go to P.E. and run laps around the football field. I can't do that.'" 

Then three months ago, Sadie received a diagnosis — she has postural orthostatic tachycardia syndrome (POTS).

POTS is believed to be an incurable chronic condition that brings about a number of symptoms including dizziness, fatigue and a rapid heart rate.

Applegate said she felt "so horrible that we didn't pay attention to it", referencing her daughter's worsening health.

"I didn't know that there could be this thing until her best friend got diagnosed with POTS, so that kind of brought it to us. I don't ever want you to feel that I'm not capable to be your protector, your mother. But you're always pretty darn cool about it, kid."

On the podcast Sadie also opened up about what it's like having a parent with multiple sclerosis (MS). 

"It's been really hard watching my mum going from this person who could get up and dance. Every night, I remember when I was a kid, we would dance and everything in her room for, like, hours at a time."

Christina Applegate on her MS.

In 2021, Applegate was diagnosed with MS.

The diagnosis occurred during the production of Netflix's Dead to Me in 2021.

Speaking to Kelly Clarkson on The Kelly Clarkson Show, she admitted: "Shooting the show was the hardest thing I've had to do in my life."

"I was diagnosed during shoot, and I didn't know what was happening to me, I couldn't walk, they had to use a wheelchair to get me to set… I was freaking out."

After receiving her diagnosis, production of Dead To Me briefly paused so Applegate could receive treatment. 

Applegate then first shared her diagnosis on Twitter in August 2021, writing: "Hi friends. A few months ago I was diagnosed with MS."

"It's been a strange journey. But I have been so supported by people that I know who also have this condition. It's been a tough road. But as we all know, the road keeps going. Unless some a**hole blocks it. As one of my friends that has MS said, 'We wake up and take the indicated action'. And that's what I do."

"So now I ask for privacy. As I go through this thing. Thank you."

It's not the first time Applegate has spoken about her health challenges.

In 2008, the actor opted for a double mastectomy after being diagnosed with breast cancer. She has been cancer-free ever since. 

Applegate has also spoken about the decision to have her ovaries and fallopian tubes removed in 2017. Applegate carried a genetic mutation called a BRCA1 mutation, which significantly increases a woman's chance of developing both breast and ovarian cancer.

In 2017, Applegate said she was concerned about passing the BRCA gene onto Sadie.

"The chances that my daughter is BRCA positive are very high," she told Today. 

"I look at her and feed her the cleanest foods. I try to keep her stress levels down. I'm doing everything I can on my end knowing that in 20 years, she'll have to start getting tested. Hopefully by then there will be advancements. It breaks my heart to think that's a possibility."

Feature Image: Getty.