The parents of a six-month-old baby are challenging doctors in court to keep their son on life support.
Connie Yates and Chris Gard's son, Charlie, is receiving 24-hour treatment at London's Great Ormond Street hospital for a rare genetic condition.
With no accepted cure for the disease, the hospital believes Charlie should be allowed to die with dignity.
Judge Nicholas Francis QC has been asked to decide whether doctors should withdraw life support treatment.
Miss Yates told the Daily Mail: "We were shocked and horrified to find we are being taken to court and that the hospital are asking for Charlie's life support to be switched off.
"I can't put into words how horrible it is to see court papers with our baby's name on them. It's as if Charlie is being sentenced to death."Image copyright PA Image caption Connie Yates and Chris Gard with their son Charlie, who was born healthy in August last year.
Though born healthy in August 2016, by the time Charlie was eight weeks old he began to lose weight and strength, she told the paper.
He rapidly declined and was admitted to Great Ormond Street in October after developing aspiration pneumonia.
He was later diagnosed with mitochondrial depletion syndrome, according to the paper, a condition so rare it is believed only 16 people in the world have suffered from it.Image copyright PA Image caption Specialists at Great Ormond Street say there is no accepted cure for Charlie's rare disease
A spokesperson for Great Ormond Street Hospital for Children NHS Foundation Trust said: "Charlie has a very rare and complex disease, for which there is no accepted cure.
"Charlie was very unwell when he was admitted to Great Ormond Street Hospital and has remained under 24-hour care on our intensive care unit.
"But his condition has continued to deteriorate and we now feel we have exhausted all available proven treatment options.
"We cannot imagine how hugely distressing this is for his family. We continue to support them in every way we can, while advocating, what we believe, is best for Charlie."Image copyright PA Image caption Charlie's parents hope to take him to the US for pioneering treatment
But Charlie's parents, who live in London, want to take him to the US, where they believe he may have a chance of surviving if he receives pioneering treatment.
Miss Yates has launched a campaign, #CharliesFight, which has raised more than £80,000 of the £1.2m she believes is needed for Charlie to receive the treatment in America.
Mr Justice Francis offered his sympathy to the couple in court, adding that the situation they were in was tragic.
Mr Francis was speaking at the initial hearing of the boy's case at the High Court in London.