(CBS) Bella Santorum, the 3-year-old daughter of Republican presidential candidate Rick Santorum, was hospitalized over the weekend with pneumonia and complications from the genetic disorder, Trisomy 18.
Also known as Edwards syndrome, Trisomy 18 occurs when a person is born with three copies of the 18th chromosome, as opposed to two. That extra chromosome interferes with typical childhood development, causing children to be born with clenched hands, crossed legs, feet with rounded bottoms, a small head and jaw, and intellectual disabilities. The disorder can also cause serious heart and kidney problems. Trisomy 18 occurs in about one out of every 3,000 births. It is three times more common in girls than boys, according to the National Institutes of Health.
Unlike Down syndrome, which is caused by an extra chromosome 21, the issues caused by Trisomy 18 are associated with more life-threatening medical complications and 50 percent of babies with Trisomy 18 who are carried to term are stillborn, according to the Trisomy 18 Foundation.
"When a child is born in this situation, they very rarely make it past the first week, because one or two problems can be overwhelming and it just kind of piles up," Dr. Brian McDonough, clinical professor of family medicine at Temple University who is not involved in Bella's care, told CBS Philly.
McDonough said that even a common cold can be deadly for a child with the disorder. He said that since the Bella is over 3 years old, she's probably undergone a great deal of medical care up until now.
"Going to the hospital certainly is not something that would be unexpected," McDonough said, "but every time a child goes to the hospital with Trisomy-18, you worry a great deal."
reported that on Sunday Rick Santorum said Bella had a "miraculous turnaround" and remains in the hospital.
The Trisomy 18 Foundation has more on the genetic disorder.