A 6-year-old has a rare disease that his mom calls Parkinson's mixed with Alzheimer's. His family hopes a scientific miracle can save his life.

• Léo Vauclare has a rare genetic disease that his parents call Parkinson's mixed with Alzheimer's.
• Léo's family has been told that, without a cure, he might not reach the age of 10.

When Deborah Vauclare cares for her 6-year-old son, Léo — who has a rare genetic disease that a doctor has told the family could be described as "Parkinson's mixed with Alzheimer's, affecting kids," according to Vauclare — she often has a helper in the form of his little sister, Eva.

"She'll kiss him and help me if his head falls," Vauclare said, adding, "She doesn't understand because she's only 3, but she likes to be with him."

Watching Eva's tenderness toward Léo gives the family some comfort, Vauclare said, as they face an uncertain future. Medical experts have told them to brace themselves for the worst. The 41-year-old mom said they told her that the maximum time that Léo has left is about four years.

"We try not to say 'poor boy' in front of Eva," Vauclare said. "But it's something we often say because the life that he lives is unimaginable."

When he was 2 years old, Léo received a diagnosis of infantile neuroaxonal dystrophy, or INAD, a neurodegenerative condition. Its symptoms of dementia are similar to those in diseases such as Alzheimer's and Parkinson's in adults. About 150 children worldwide are known to have it, Vauclare said.

One of the causes of INAD is a missing enzyme in people's bodies as well as a dangerous accumulation of iron. It often results in blindness, poor motor function, seizures, hearing loss, and problems with swallowing and breathing.

Léo's sister had a 25% chance of having the same genetic condition as her brother

Vauclare, who learned of Léo's condition when she was five months pregnant with Eva, was told that a recessive gene caused it, and that her unborn baby had a 25% chance of developing it, too.

"I was a complete wreck," said Vauclare, a New Yorker who lives in France with her 46-year-old husband, Antoine Vauclare. "I couldn't sleep. I couldn't eat and felt nauseous all the time from nerves."

Thankfully, Vauclare said, when Eva was at seven months' gestation, tests showed that she was free of the disease and would be born healthy. But, she added, the results couldn't take away their fears for Léo.

"We thought, 'How can this be?'" Vauclare said, adding, "We thought, 'How could our child — or any child — be given this life, which is really not much of a life?'"

Léo began to show symptoms of the condition when he was 14 months old. He failed to meet the usual developmental milestones. In addition to issues such as speech delay, his balance "was off," and he "kept falling down," Vauclare said. He was assessed by therapists before having routine tests, such as an MRI and EEG. But "the disease didn't show up yet," Vauclare said.

The family underwent genetic testing in June 2018 and learned that Léo had INAD. Vauclare said that, to their frustration, the doctors in Paris "seemed more concerned" about the baby she was carrying than about Léo.

"I remember being furious," she said. "They were saying, 'What about your daughter?' and insinuating, "Are you going to terminate your pregnancy?' and I was like, 'What are you going to do about our son?'"

Vauclare said they were handed a leaflet about INAD and left to research it themselves on the internet. She then came across the INADcure Foundation, which supports the families of the small number of children with the condition, and fought to find a cure for them and Léo.

In a race against time, the Vauclares joined forces with the charity to launch an initial $500,000 campaign called Bisous for Léo to fund scientific research.

Léo was enrolled in an drug trial in Morristown, New Jersey, six months after his diagnosis. The research continued until 2021, when, Vauclare said, the company behind it went bankrupt. He was denied the chance to take part in a subsequent trial because his disease had become "too advanced," and "it would not only not help him but probably make it even worse," Vauclare said.

The Vauclares said they've watched Léo go from a smiling toddler to a child who's barely conscious of his surroundings. He has a feeding tube and a molded seat that supports his head and body.

Still, he goes every day to a special center that caters to children with disabilities. Vauclare said he receives aqua and light therapy to "help with his sensory needs." She believed that a highlight of his week was a "dog therapy" session where he and other kids got to "pet, feed, and train" the animals.

The INADcure Foundation needs to raise millions to fund a new gene-therapy treatment for kids such as Léo

Meanwhile, the family clings to the hope that a scientific miracle could save Léo before it's too late. The INADcure Foundation needs to raise $7 million to pay for the development of a new gene-therapy treatment for the disease in the US.

"They say it's going to be ready in 18 to 24 months," Vauclare said, adding, "Will he be eligible for the trial? Does he have another 18 to 24 months to live?"

As they continue to wait, Vauclare said, Léo will always know that he is loved. His mom, dad, and little sister will protect him forever, she added: "The only thing I can really do now is to hold him for as long as I can."