(CNN) Five-year-old Julianna Snow has never been healthy enough to attend Sunday school at the City Bible Church in Portland, Oregon, where her family belongs, so most of what she knows about heaven, she knows from her parents.

They tell her that heaven is where she'll be able to run and play and eat, none of which she can do now. Heaven is where she'll meet her great-grandmother, who shared Julianna's love of shiny, sparkly, mismatched clothes.

God will be in heaven, too, they tell her, and he will love her even more than they do.

But Michelle Moon and Steve Snow explain that they won't be in heaven when Julianna arrives there, and neither will her big brother, Alex. She'll go to heaven before them because she has a severe case of an incurable neurodegenerative illness called Charcot-Marie-Tooth disease.

Her coughing and breathing muscles are so weak that the next time she catches even a cold, the infection could settle in her lungs, where it could cause a deadly pneumonia. Her doctors believe that if they can save her under those circumstances -- and that's a big if -- she will likely end up sedated on a respirator with very little quality of life.

There's no debate about the medical facts of Julianna's condition. But there is debate about something her parents have chosen to do: They asked their daughter, at the age of 4, if she would want to go to the hospital the next time she becomes dangerously ill, or would she want to stay home, where she would die.

Julianna has said she doesn't want to go to the hospital. She wants to go to "heaven."

Before having these discussions with her daughter, Michelle looked online for guidance about end-of-life talks with a 4-year-old. Finding nearly nothing, she started a blog of her own in hopes of helping other families in the same situation. Later, she contributed to The Mighty , a website where people write about grappling with disabilities and devastating diseases.

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Michelle: Julianna, if you get sick again, do you want to go to the hospital again or stay home?

Julianna: Not the hospital

Michelle: Even if that means that you will go to heaven if you stay home?

Julianna: Yes... I hate NT (naso-tracheal suction, where a tube was placed down her nose into her lungs without sedation). I hate the hospital.

Michelle: Right. So if you get sick again, you want to stay home. But you know that probably means you will go to heaven, right?

Julianna: (nods)

Michelle: And it probably means that you will go to heaven by yourself, and Mommy will join you later.

Julianna: But I won't be alone.

Michelle: That's right. You will not be alone.

Julianna: Do some people go to heaven soon?

Michelle: Yes. We just don't know when we go to heaven. Sometimes babies go to heaven. Sometimes really old people go to heaven.

Julianna: Will Alex (her 6-year-old brother) go to heaven with me?

Michelle: Probably not. Sometimes people go to heaven together at the same time, but most of the time, they go alone. Does that scare you?

Julianna: No, heaven is good. But I don't like dying.

Michelle: I know. That's the hard part. We don't have to be afraid of dying because we believe we go to heaven. But it's sad because I will miss you so much.

Julianna: Don't worry, I won't be alone.

Michelle: I know. I love you.

Julianna: Madly.

Michelle: Yes, I love you madly. I'm so lucky.

Julianna: And I'm so lucky.

Michelle: Why?

Julianna: Because you love me madly.

Photos: A child decides: Heaven or hospital? Julianna Snow, 5, is dying of an incurable disease. Counseling has helped prepare her brother, Alex, for his younger sister's death. He asked if his mom's heart would stop beating when his sister dies because she will be so sad. Hide Caption 1 of 14 Photos: A child decides: Heaven or hospital? Julianna, who has Charcot-Marie-Tooth disease, once had nearly full use of her arms, but now can't even hold a small toy without help. Her mother, Michelle Moon, brushes her teeth. Hide Caption 2 of 14 Photos: A child decides: Heaven or hospital? Steven Snow's mild case of Charcot-Marie-Tooth disease has manifested as a severe case in his daughter Julianna. Hide Caption 3 of 14 Photos: A child decides: Heaven or hospital? Julianna spends nearly all her time in her "princess" room. Sometimes she pretends her bed is a magic carpet. Hide Caption 4 of 14 Photos: A child decides: Heaven or hospital? If Julianna gets sick, Michelle says she will ask her again if she wants to go to the hospital or heaven, and "we'll honor her wishes." Hide Caption 5 of 14 Photos: A child decides: Heaven or hospital? If she gets an infection, she says she wants to die at home instead of going to the hospital for painful treatments that are unlikely to save her. Julianna asked if her brother, Alex, would go to heaven with her when she dies.

Hide Caption 6 of 14 Photos: A child decides: Heaven or hospital? Julianna is rarely without her breathing mask. Hide Caption 7 of 14 Photos: A child decides: Heaven or hospital? A pressurized mask pumps air into Julianna's lungs. An incurable neurodegnerative disease has attacked the nerves that control her muscles, including those that control her breathing. Hide Caption 8 of 14 Photos: A child decides: Heaven or hospital? Julianna loves to wear colorful dresses and have her nails painted. Hide Caption 9 of 14 Photos: A child decides: Heaven or hospital? At one point, Julianna ate food, but now her chewing and swallowing muscles are so weak she's fed through a tube in her stomach. Hide Caption 10 of 14 Photos: A child decides: Heaven or hospital? Initially, Julianna's parents arranged for braces on her ankles and feet in hopes she might walk one day, but now they say they know that day will never come. Hide Caption 11 of 14 Photos: A child decides: Heaven or hospital? Julianna shows no envy toward Alex, who can race up and down the hallway and do martial arts. Hide Caption 12 of 14 Photos: A child decides: Heaven or hospital? Michelle reads to Julianna. Her mother has made sure Julianna understands that going to heaven means "dying and leaving this Earth." She also told her it meant leaving her family for a while, but they would join her later. Hide Caption 13 of 14 Photos: A child decides: Heaven or hospital? Michelle, Julianna, Steve and Alex spend time together in the family's living room. Hide Caption 14 of 14

Before these conversations, Michelle says she and Steve had planned to take Julianna to the hospital if she were to get another infection. But after hearing Julianna's wishes, they changed their minds.

"She made it clear that she doesn't want to go through the hospital again," Michelle wrote CNN in an email. "So we had to let go of that plan because it was selfish."

While most readers left supportive comments on her blog post, some thought Michelle and Steve had made the wrong choice.

"Unbelievable that any parent would think a 4-year-old is able to understand or make a decision on life," commented one mother of a child with a chronic illness. "Clearly that mother asks her leading questions. This article sickens me."

The next week Michelle posted another blog post, further explaining their decision

"She's scared of dying, but has, to me, demonstrated adequate knowledge of what death is. (J: 'When you die, you don't do anything. You don't think.')," Michelle wrote. "She hasn't changed her mind about going back to the hospital, and she knows that this means she'll go to heaven by herself. If she gets sick, we'll ask her again, and we'll honor her wishes."

She continued: "Very clearly, my 4-year-old daughter was telling me that getting more time at home with her family was not worth the pain of going to the hospital again. I made sure she understood that going to heaven meant dying and leaving this Earth. And I told her that it also meant leaving her family for a while, but we would join her later. Did she still want to skip the hospital and go to heaven? She did."

Should a child decide her own end-of-life care?

For adults, end-of-life decision-making is relatively straightforward: Basically, we get to decide how much medical treatment we want and don't want.

But how much say should a child get? And at what age?

Without realizing it, Michelle and Steve had stepped into a heated debate.

Julianna toward the end of her third hospitalization in October 2014.

Bioethicist Art Caplan has read Michelle's blogs, and he thinks she's made the wrong decision.

"This doesn't sit well with me. It makes me nervous," he says. "I think a 4-year-old might be capable of deciding what music to hear or what picture book they might want to read. But I think there's zero chance a 4-year-old can understand the concept of death. That kind of thinking doesn't really develop until around age 9 or 10."

He says Julianna's parents shouldn't put any stock in what she has to say about end-of-life decisions. Maybe she chose heaven over the hospital because she feels how much her parents hate to see her suffer; young children often pick up cues from their parents and want to please them, he says.

Caplan, before he started the bioethics program at New York University a few years ago, worked at the University of Pennsylvania and consulted on end-of-life cases at Children's Hospital of Philadelphia with Dr. Chris Feudtner, a pediatrician and ethicist there. Caplan respects him a great deal.

Feudtner, it turns out, disagrees with Caplan about Julianna.

"To say her experience is irrelevant doesn't make any sense," he says. "She knows more than anyone what it's like to be not a theoretical girl with a progressive neuromuscular disorder, but to be Julianna."

At his hospital, he has asked dying children her age what they want to do, and in the appropriate circumstances, he has taken it into consideration.

For example, he doesn't take their opinion into account when it's a black and white decision -- children with treatable leukemia must get chemotherapy, for example, no matter how hard they protest. But when the choice is gray, when there's more than one reasonable option, as there is with Julianna, he has put stock in their wishes.

As for a 4-year-old not having the mental capacity to think through death, he's found that even adults often don't think through such issues as carefully as one might like.

"My 86-year-old father died in April, and I'm not sure he truly got it," he says. "He was bed-bound from cancer, and he said, 'If this is the best I get, get me a Smith & Wesson.' Did he mean that? I don't know."

Feudtner, the chairman of the American Academy of Pediatrics section on hospice and palliative medicine, says as best he can tell from Michelle's blogs, Julianna's choice for heaven over the hospital is reasonable and her parents are right to listen to her.

"Palliative care isn't about giving up. It's about choosing how you want to live before you die," he says. "This little girl has chosen how she wants to live."

Julianna is no ordinary 5 year old

Art Caplan's words sting Michelle when she hears them. How could he deign to understand her child? But then a few days later, she wrote to CNN to say that she understands how someone could have a difficult time understanding what she and Steve have decided.

If you haven't met Julianna, she says, it's hard to explain how even at such a young age, she understands the choice that's in front of her, how she's the one who experiences the suffering and should get a say in what will happen to her.

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The doctors and nurses who know Julianna best agree.

Dr. Danny Hsia, her pulmonologist, observes that Julianna is wiser than most 5-year-olds. "In that case, it makes a lot of sense to listen to her. I have the utmost faith in her mother and father. They're phenomenal parents and have her best wishes at heart," he says.

He believes that when Julianna gets another infection, the hospital will likely not be able to save her. "For her, there is no light at the end of the tunnel," he says, his voice trailing off. "She doesn't have a long time to live."

Diana Scolaro, the nurse who took care of Julianna through three stays in the intensive care unit, also supports Steve and Michelle's decision to listen to their daughter. "You have to know what it's like to hold down a child and hear them scream so you can stick a tube down their nose. It's one thing to do that when you know you'll have a success at the end, but for Julianna, there is no success," she says. "We pulled her from death's door so many times last year, but she's sicker now than she was then, and I don't think we could pull her through another big crisis."

Scolaro cries as she tries to express her wishes for Julianna. "I want her living and dying in her princess room, at home, surrounded by her family, not in the cold technology of a hospital," she says. "There is no cure for her. Every day is a blessing. Every day is a gift."

Planning for heaven, enjoying life

For now, Julianna spends nearly all her time in that princess room. In her closet hang dresses for pretty much every Disney princess there is, and each morning she picks out which one she wants to be. Some days she's Rapunzel, other days she's Snow White or Belle or Cinderella or Sleeping Beauty.

She's happy, watching videos and chatting nonstop with a steady stream of family, friends and nurses. She makes up elaborate fantasies, that her bed is a magic carpet, that she and her grandmother go on a shoe shopping trip together; Julianna buys one high-heeled red pair and one "low-heeled" blue pair. Then, they go to a restaurant and she orders macaroni and cheese.

Julianna recently celebrated her fifth birthday in a tiara and princess dress.

Julianna displays no bitterness that she can't actually eat real food or go on a shopping trip. Instead, Julianna smiles as she watches her brother race up and down the hallway, showing no envy. Her father wheels her into the dining room to eat with the family, and takes a piece of cheese off the pizza and rubs it on Julianna's lips so she can have a taste, and then does the same with a piece of pineapple topping. She never once says how nice it would be if she could eat the pizza like everyone else at the table.

Her parents watch as her disease gets worse in just a matter of months. Last year, on the Fourth of July, Julianna impressed the neighborhood kids by turning circles in the driveway in her wheelchair, working the hand controls by herself. About six months later, her hands were too weak to work the controls at all. In those same six months, she went from needing the breathing mask only while sleeping to needing it nearly all the time.

Michelle and Steve try to prepare themselves and Alex for Julianna's death. Counseling for all of them has helped. Alex is just 6 and doesn't say much, but then he'll surprise his parents by blurting out something insightful.

Once, he asked Michelle if her heart would stop beating when Julianna dies because she will be so sad.

Some days Michelle feels like it will. Other times she doesn't focus on Julianna's death, and just feels grateful to be with her. In a post this summer on The Mighty, she described her daughter's mind and spirit as " bright, sharp and lovely ."

Julianna used to turn circles in her wheelchair. Now her hands are too weak to work the controls.

Julianna is planning for her future in heaven, and for her parents' eventual arrival there.

"Do you want me to stand in front of the house, and in front of all the people so you can see me first?" she asks.

"Yes," her mother answers.

"And will you run to me?" she asks.

"Yes, I will run to you," Michelle answers. "And I think you'll run to me, too."

"I'll run fast," Julianna responds, shaking her head back and forth to show how fast she will run.

It has been a year since Julianna last had an infection, and these months have been "a dream," Michelle says. But she knows it won't last forever. Any little cold could ruin the lovely dream. Her medical training and her faith tell her that she and Steve and Julianna will know when the end is near. And they will make a decision about what to do. Together.