"Kids can slowly develop the disorder and have symptoms or heart manifestations, or stressors to the heart can be a signal," he said.
"Basically, there is no treatment," Cuevas said. "Nothing we can offer allows the child to breathe well. We treat the symptoms."
Children with the disorder are most vulnerable at night and rely on a ventilator, one much the same as those used during anesthesia. But long-term use of these machines can put children at risk for life-threatening infections and pneumonia.
Sometimes, a pacemaker is used to stimulate the diaphragm muscles instead of a ventilator, but it is more often used to treat adult patients.
"I've heard of kids who survived into teen-hood and even into adulthood," said Cuevas. "But it's tough."
As for Liam, he underwent a tracheotomy and wears a breathing tube.
"We have to keep a very close eye on him," said his mother. "He goes from being totally active and then his heart rate slows right down."
Ondine's Curse is actually a misnomer, probably to "to sell newspapers," and does not adequately describe children like Liam, according to Dr. Mark Dyken, a neurologist and director of the Sleep Disorders Center at the University of Iowa.
"While you are awake, you can initiate your own breathing and overcome the autonomic center," said Dyken. But a person cannot forget to breathe.
The name first was coined in 1962 to describe a syndrome that was manifested in three adult patients after high cervical and brain stem injury. Later, in 1970, three babies were diagnosed with the congenital disorder.
Sometimes the dorsal respiratory center similarly is damaged by a brain injury or stroke.
Liam was lucky, according to Dyken.
"His parents should be proud," Dyken said, "and it's smart the doctors immediately diagnosed it -- whatever you want to call it."
But breathing wasn't Liam's only problem,
At birth, he had a large neoblastoma, a virulent form of cancer that is now in remission, and his bowel was removed, according to Liam's doctor.
"Most children would have died of the cancer taking over their body cavity," said Connett. "Fortunately, what was left disappeared spontaneously."
Liam also has Hirschsprung's disease, a condition that affects the large intestine. He also must eat large quantities of food because his colon cannot properly absorb nutrients.
Doctors are hopeful that in two years, Liam might be able to be weaned off the night ventilator and use a face mask, one similar to those used for treating sleep apnea.
"He could live well into adulthood, and be employed and be an integral part of society," said Connett. "He's doing well."
Liam's family also gets support to hire a caregiver to look after him at night so his parents can sleep.
"We have to keep a very close eye on him," said Derbyshire. "He goes from being totally active and then his heart rate slows right down."
But Liam is "so full of life," according to his mother.
"He's constantly smiling and laughing," said Derbyshire. "He's very affectionate. He has all the normal traits of a lot of kids. Every day of his life is a bonus."
He is passionate about trains, and on his 11th birthday on Aug. 3 South West Trains let him ride next to the driver from his school in Fareham to London's Waterloo station.