Give Baby Charlie the experimental treatment, say US parents whose son has similar disorder Charlie Gard was born with a rare form of mitochondrial depletion syndrome.

 -- Baby Charlie Gard’s parents have been locked in a bitter fight for their son’s future, not only for his survival against a debilitating disease, but against the London hospital where he has been a patient since he was just 2 months old and the British courts who say his condition is too grave to continue keeping him alive.

“Our parental rights have been stripped away,” his father, Chris Gard, said in a video he and his wife posted online. “We can’t even take our own son home to die.”

Gard and his wife Connie Yates’ son Charlie, who is now 11 months old, was born with a rare form of mitochondrial depletion syndrome, a genetic disease that has left him severely brain damaged. Doctors at Great Ormond Street Hospital say he can’t see, hear, move or cry.

His parents living in London want him to undergo an experimental treatment in the United States, but doctors say Charlie could be in pain and that the new treatment is unlikely to help him. Multiple British courts in Europe have ruled that he is too weak to travel out of the country and he should be allowed to die with dignity. It’s ignited a fierce debate between hospitals wanting to treat patients as they see fit and parents who want to make decisions for their child. In the U.K., it’s not uncommon for courts to side with hospitals over parents.

“In the U.K., doctors have somewhat more discretion than the U.S.,” said Dr. Rosamond Rhodes, a medical ethicist. “The doctor’s argument is that this child is suffering, and I haven't seen any evidence that clearly makes the case for knowing that the child is suffering.”

Charlie’s parents’ pleas have even grabbed the attention of Pope Francis, who extended his support to the family, and President Donald Trump, who tweeted, “If we can help little Charlie Gard, we would be delighted to do so.”

One American family from Baltimore understands the unimaginable circumstances Charlie’s family has been going through.

Art and Olga Estopinan’s 6-year-old son Art Jr. was diagnosed with a similar mitochondrial depletion syndrome when he was just over a year old. Like Charlie, doctors had told his parents there was little chance of survival.

“We were told there was no hope and no cure,” Olga Estopinan said. “He was terminal and average age for these children was 3 years old.”

At his worst point, Olga said their son was “lying in a hospital bed and the most he could do sometimes was move his head just a little bit ... he couldn’t even shed tears.”

“He had multiple fractures in his legs and his arms and he couldn’t cry,” Art Estopinan added. “His disease was really advanced and he was basically dying on us.”

But what his parents call a miracle appeared in the form of a pioneering experimental treatment called nucleoside therapy. Art Jr. was the first child in the U.S. to get the treatment five years ago.

Dr. Michio Hirano of Columbia University Medical Center in New York administered their first trial, along with other doctors at Johns Hopkins Hospital.

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“We were very lucky,” Olga Estopinan said. “His geneticist Ada Hamash ... [was] like, ‘There’s hope for this, let’s go ahead and try,’ and I will never, ever in my mind forget how special that women is.”

The Estopinans said little Art Jr. went from being on the brink of death to gaining back some motor functions. He can now find and play movies on an iPad and say “mommy, daddy,” and a few other words.

“He’s a determined little boy,” Art Estopinan said.

But even with his incredible progress, the Estopinans are quick to note that the treatment their son had is not a cure for his condition. Art Jr. requires round-the-clock care. He gets three to four treatments per day, is fed through a feeding tube, is in a motorized wheelchair and needs help moving his limbs.

“We have like six alarms, and he has like eight different machines to keep him alive,” Art Estopinan said.

“And no matter in the middle of the night, when we hear one of the alarms, we both jump up.”

Dr. Mary Kay Koenig is a specialist in mitochondrial disease at the Children's Memorial Hermann Hospital in Houston, and said the earlier a patient shows symptoms, “the more severe the outcome” is for the patient.

“Patients develop muscle weakness. They can develop nerve damage. They can develop seizures,” Koenig said. “Unfortunately right now there are no therapies that we know of that can stop the progression of the mitochondrial disease.”

But despite that, the Estopinans say they would rather have Art Jr. as he is than not have him at all. The Estopinans say they share Charlie’s parents’ suffering.

“With all due respect to [Charlie’s doctors,] … I encourage those doctors ... to educate themselves,” Art Estopinan said. “See how these experimental medications will create the end signs that little Charlie needs so he can get stronger like my son.”

Last week, Charlie's parents won a small victory when the British High Court ruled that Charlie could be evaluated by the same doctor who helped Art Jr., Dr. Michio Hirano. Hirano flew to London to examine Charlie and the hospital expects to release an assessment by Thursday.

Charlie’s parents have raised nearly $1.7 million to pay for the experimental treatment in the U.S. with Hirano, but the attention is on Charlie’s brain condition and whether or now the proposed treatment can help reverse the disease or if there is already too much damage. Their hope is that their son will be Hirano's next patient.

“What other options do we have?” Charlie's mother, Connie Yates, told the BBC. “Charlie’s our son, we love him, and we will fight to the bitter end for him.”

ABC News' Lauren Effron contributed to this report