KNOXVILLE, Tenn. (WVLT) -- Brynlee Roy was born with ten fingers and ten toes, but she was also born with a deadly disease.

"She looked perfectly healthy on the outside," said Mark Roy, Brynlee's father.

A newborn screening showed the little sister was born with a rare hereditary affliction known as Pompe Disease.

"It's a tragedy you never want your newborn child to be born with, a disease that affects them for the rest of their life, and have to go through so much at such a young age," said Sarah Roy, Brynlee's mother.

The rare diagnosis indicates an inherited disorder that is caused by the buildup of a complex sugar called glycogen in the body's cells, according to the National Library of Medicine.

"The state does it in the newborn screening and thankfully they started testing in July of this year for that, or we would have no idea," said Mark.

Pompe disease is so rare that Sarah Roy said she believes her daughter is the first one to be treated at East Tennessee Children's Hospital.

According to the National Library of Medicine, infants diagnosed with this disorder typically experience muscle weakness, poor muscle tone, an enlarged liver and heart defects. Affected infants may also fail to gain weight and grow at the expected rate, and they may experience breathing problems. If the disease goes untreated, it could lead to death from heart failure in the first year of life.

"It affects her muscles, her respiratory, and cardiac system," Sarah said. "She's also going to have a port placed for medications."

At one month old, Brynlee has spent nearly as much time in the doctor's office as she has in her own crib.

"It's the toughest news I've ever had to deal with," Mark said. "It's definitely something that brings you to your knees. It's something we weren't expecting to find out."

The Roys said they have to watch doctors and nurses prick their baby girl with needles, and they will watch her grow up in a hospital; however, they said friends and family are taking some weight off their shoulders. 

"Being from Greenback, everybody reaches out and it's just a big family, and it's amazing how many people have reached out already, even before the benefit, wanting to help us and her daughter," Sarah said.

The benefit for the Roy family to help raise funds for Brynlee's treatment was set to be held Sunday from 4 until 6 p.m. at the Greenback Community Center. All proceeds will go directly to the Roy family.