Caleb smacked the palm of his hand and raised it in the air toward his older brother’s face.

“You see this?” he said, pointing to his outstretched hand.

His 12-year-old face was serious — too serious. You could tell he was struggling to hold back a grin.

“It’s going to become your worst nightmare.”

15-year-old Tanner was quick with a spar back.

“What? Your pinky finger,” he said, chuckling, before flicking Caleb behind the ear.

Brothers Tanner, 15, and Caleb, 12, are like a lot of siblings. They tease and fight — all in good natured brotherly love. And they’re also each other’s biggest defenders.

Both born with the genetic disease, cystic fibrosis, Tanner and Caleb are close — even when their disease requires them sometimes to be six feet apart.

Cystic fibrosis — often shortened to CF — is a disease that causes severe damage to the lungs, digestive system and other organs in the body. Patients often are required to stay six feet away from others with CF to prevent the spreading of germs, which can be difficult to treat and lead to a faster decline in lung function.

But for Tanner and Caleb, they’re only kept apart when they are sick.

Otherwise, they spend time doing brotherly things like gaming, rollerblading and playing baseball.

There’s currently no cure for CF, and that means the brothers spend hours each day working to live with their disease.

There are daily breathing treatments, which they usually spend wrapped under fuzzy blankets on the couch together watching a movie on high volume, as machines whir in the background and a vibrating vest shakes mucus from their lungs and opens their airways.

And there are dozens of pills — more than 30 for Caleb — that they take every day before meals to help them digest their food.

“CF makes me feel different. I stand out,” Caleb said. “In P.E., we have to run a mile every month, and I’m usually the last person to finish.”

About a decade ago, the family relocated to North Texas for the boys to be treated at Children’s Health, after doctors at a previous hospital told their parents that they had exhausted their options to help then-5-year-old Tanner.

“Instead of prepping for the end of Tanner’s life, we visited other hospitals and landed on Children’s Health because it is ranked highly for treating cystic fibrosis,” Kiri, the boys’ mom, said. “Instantly, Tanner started to get better.”

The Claude Prestidge Cystic Fibrosis Center at Children’s Health is a leader in the care of pediatric cystic fibrosis patients, caring for more than 300 children each year in North Texas. The center incorporates a multidisciplinary approach to treating CF patients, providing families access to the best care possible, including cutting-edge treatments and clinical trials.

“When Tanner and his family came to us, they wanted to fight, and we wanted to fight alongside them,” said Preeti B. Sharma, M.D., the family’s pediatric pulmonologist and co-director of the Cystic Fibrosis Care Center at UT Southwestern and Children’s Health. “Having access to both a pediatric gastroenterologist and a pediatric pulmonologist, along with a whole team of specialists, was key to moving the bar forward for him to enhance his growth and his pulmonary function.”

Children’s Health participates in the Cystic Fibrosis Therapeutics Development Network, the largest cystic fibrosis clinical trials network in the world. Our affiliation with this network ensures that our patients benefit from the latest drug trials, clinical studies and a wealth of research in cystic fibrosis treatment.

This collaboration means an improvement in patient outcomes, advancing treatments and prognosis for children with cystic fibrosis — even since Tanner and Caleb were born.

“New treatments have altered the life expectancy for people with cystic fibrosis dramatically. People with CF are living longer, healthier lives,” Dr. Sharma said. “And we wouldn’t have made any of these advances without the support of the community to help fund research and to advance how we care for CF patients.”

In the last decade, these therapies have changed the day-to-day life of many patients, improving their lung function, gastrointestinal symptoms and overall energy. Kids feel better and spend less time sick in the hospital. Many also live to be middle-aged adults.

“We started out thinking that our sons weren’t going to graduate high school, and now they have the possibility to live to age 30 or 40,” Stephen, the boys’ dad, said. “They can live a full life. They can have their own kids. They can have a career. They can go to college. They can do anything they want.”