Isaac Brown felt no pain when he crunched a glass bulb from a nightlight in his mouth, pressed his hand against a hot stove top burner or plucked his eyelashes out with a toenail clippers while seated on his sister's bed.
A recent tumble from some playground equipment landed the 4-year-old Mapleton, Iowa, boy in a blue cast that stretched from his toes to his groin.
"It didn't hurt," the fair-skinned child with rosy cheeks and blue-gray eyes exclaimed with a wide smile.
When he was 2 years old, doctors at the Mayo Clinic in Rochester, Minn., diagnosed Isaac with Congenital Insensitivity to Pain with Anhidrosis (CIPA), a rare nervous system disorder that prevents him from feeling physical pain.
"He can't pinpoint like a normal kid who's fallen, 'I hurt here or I hurt there,'" said mom Carrie, as Isaac, dressed in a black T-shirt printed with the words "Team Painless," sat sandwiched between her and his dad Randy on a bluish green sofa in their living room.
Isaac gently kicked his feet up and down and then rested his chin in his palms. Candles flickered on an upright piano behind the couch. The Browns' other six children, ages 6 to 17, sat at the edge of the dinning room peering in.
This untreatable disease, which affects fewer than 100 people in the United States, also makes Isaac unable to sweat and feel extreme heat and cold.
"We consider him pretty normal," Randy said. "Other kids have had all their teeth removed because they would self-mutilate, bite their tongues, chew their fingers off."
Isaac acted like any "normal" child on that mild December afternoon, 12 days before Christmas.
He drew pictures with pastel chalk on the stepping stones that lead from the dirt driveway to the front door of his family's quaint white farmhouse with black trim.
He gripped a white plastic sifter in his hands and watched a mixture of ground cornmeal and coffee slide through the holes into his "indoor sandbox," a long clear tub.
Ask Isaac's siblings if playing with him is any different than playing with any other kid, they'll shake their heads "no."
"We make sure he doesn't get too rough. He falls down easily," said Jessica, 16.
Isaac's medical condition is anything but ordinary. It seems somewhat superhuman and at the same time extremely dangerous.
Carrie said CIPA has "tested" her family, who turn to their Christian faith to help them cope with it.
"We just want Isaac to have a normal future," she said. "People can live a normal life with this, they just have to really be aware of their own body."
FEELING NO PAIN
Isaac was a healthy, happy baby who didn't seem to cry very much.
Everything changed, when at 8 months, he sank his tiny hand into a steaming cup of coffee.
His face didn't tense up. Tears didn't well in his eyes. He didn't scream. He didn't snatch his hand away.
That was the first time the Browns noticed something wasn't quite right with their son.
"We got his fingers wiped off before they got burnt," Randy recalled. "He did it again a couple months later."
Carrie mentioned the incident to Isaac's pediatrician during a regular checkup. The doctor advised her to "keep an eye on it."
Isaac had a few more mishaps in the following days, weeks and months.
He tumbled down the stairs.
He hit his head.
He fell through a circular heating vent cut in a second floor bedroom, bounced off the living room couch and landed in a box of socks.
"Somebody had moved the cover off (the vent)," Carrie said. "He had little to no reaction to that. It scared him."
Another time Carrie opened the bathroom door to find Isaac tightly gripping a broken china cup in his hand. The sharp edges didn't seem to faze him. She wondered, "Why do you do this?"
In October 2009, Isaac, then 17 months, set his hand on top of a hot burner. He didn't feel the searing heat, and his 12-year-old brother Jacob had to lift his red, blistered hand off the burner.
Carrie and Randy rushed Isaac, who had suffered second and third-degree burns, to the emergency room.
Concerned about their son's lack of reaction to a painful injury, the Browns took Isaac to see a neurologist in Omaha.
A MRI offered the Browns no explanation for Isaac's alarming behavior, but the neurologist suspected that the boy could have Congenital Insensitivity to Pain. The next and only option was genetic testing, which would cost upwards of $70,000.
"Even if it came back that he had this genetic disorder, there was nothing they were going to be able to do about it, so the insurance wasn't going to cover it," said Carrie, whose family lives solely off her husband's nursing salary. "We couldn't afford that."
Since there was nothing physically wrong with Isaac, the Browns went home and resumed their life as normal until March. That's when Jessica walked into her bedroom to find her brother's face scattered with his eyelashes. Isaac had pulled a third of them out with a toenail clippers and nicked his face in the process.
The incident was a turning point for Carrie. She had had enough.
"I went upstairs crying," she said. "I don't know how to deal with this anymore. He's physically hurting himself now on purpose. Before it was accidents that happened."
Soon after Isaac yanked out his eyelashes, Carrie called the Mayo Clinic in Rochester, Minn. The family traveled there in July 2010.
A neurologist conducted developmental screening tests to determine what he was capable of doing physically and cognitively. She poked his skin with pointy objects and held a hot plate against the bottom of his foot and his hand for two seconds. He didn't flinch.
"He actually grabbed it and held on to it and would not let it go," Randy said.
Isaac was diagnosed with Congenital Insensitivity to Pain with Anhidrosis. He was enrolled in a study under the direction of Christopher Kline, a neurologist and geneticist, at no cost to his family.
A sample of Isaac's DNA, which is currently being analyzed, will be compared with DNA samples of other children who have the same condition. By next summer, Randy said Kline hopes to have identified the genetic mutation that has prevented Isaac's body from forming nerve cells responsible for transmitting signals of pain, heat and cold to his brain.
"I always had a hope that there was something else causing it," Randy said. "After talking to (Kline), I'm leaning more that maybe this really isn't anything else. The good thing is knowing it's manageable. That's comforting in itself."
LEARNING WHAT PAIN IS
Teaching Isaac to react to pain that the average child feels, the Browns said is challenging.
When Randy accidentally stepped on his son's foot with his boot, Isaac giggled. He told his son that that hurts and that he should say, "Ow!"
Later that day when the cat brushed up against him, Isaac mistakenly responded with "Ow!"
"He knows blood is bad," Carrie said. "He will tell us when he's hurt himself, especially if he sees blood."
Anytime Isaac injuries himself, the Browns have to report it to Isaac's doctor. An X-ray is often required, as it was when Isaac fell from the playground equipment. Doctors suspected that he may have fractured his foot and possibly his pelvis. If Isaac continues to limp, Carrie said he will return to the Mayo Clinic at the end of January for further evaluation.
Insensitivity to pain isn't the most difficult aspect of Isaac's condition. Carrie said it's his inability to feel extreme temperatures.
Isaac could be on the verge of heatstroke while playing outdoors and not even know it. That's why his sandbox is indoors.
Carrie takes Isaac to the library when temperatures are cool, but she avoids the community pool. Isaac went swimming there once on a chilly overcast day. He loved it. The rest of his family did not.
"Really just to get in the car and drive anywhere in the summer with him is just dangerous," Carrie said. "What if we had a flat tire? Those kinds of things worry us."
The danger is just as real in the wintertime with frostbite.
A few weeks ago, when Randy came home from work, he was greeted outside by a shoeless, sockless Isaac. The ground was covered with snow.
"I picked him up and said, 'Aren't you cold?" Randy recalled. "He said, 'Yeah. I'm cold.' I asked him, 'Are your feet cold?' He goes, 'No.'"
Carrie is always checking Isaac's temperature. A few times during the hour-long interview, she gently placed her hands on Isaac's flushed cheeks and the back of his neck.
The Browns keep their thermostat set in the mid- to low-60s in the winter and they cover their windows with black plastic garbage bags in the summer to keep Isaac cool.
When they take him out in public, they have to ask themselves, "Is this room too hot for Isaac?"
There's always a chance that Isaac could overheat. Carrie was reminded of this at a church Christmas program earlier this month.
With temperatures hovering in the 40s, Carrie said she didn't think to bring Isaac's special vest, hat and wristbands, that when submerged in cold water cool his body temperature. Isaac got too hot during the program, and Carrie had to take him outside and sit on the church steps with him.
"I don't watch my kid any closer than a normal parent watches their kid, but it's something all of us have to think about when we walk into the grocery store, when we walk in anywhere," said Carrie, who home schools her children.
After Isaac burned his hand on the stove top, Carrie did an Internet search for "kids who don't feel pain."
She stumbled upon a blog written by a woman living in the United Kingdom. She e-mailed the woman, who referred her to a private Facebook group called "A Gift of Pain."
Carrie joined the Facebook group and met several other families with children facing the same challenges as Isaac.
Last November, the Browns loaded up a 15-passenger van and set out for Winder, Ga., where they attended Camp Painless But Hopeful, a camp for children who don't feel pain and their families.
The camp is the brainchild of Ashlyn Blocker, a 13-year-old girl from Patterson, Ga., who also suffers from CIPA. Blocker's story has been featured on the "Today Show" and in People and the New York Times Magazine.
At the camp, which was attended by eight families, Isaac played with other children while Randy and Carrie gleaned advice from their parents.
"We decided it was so beneficial to us and we had such a great time that we thought we would do whatever it took to get there again," Carrie said. "All summer long, Isaac talked about going back to camp."
This year, Carrie sold pies at a church function and held a Pampered Chef party to help raise money for Isaac's second trip to camp, which was more memorable than his first.
This year he rode a train, swung on a giant swing and climbed a rock wall, a daring feat for a 4-year-old.
"He's a daredevil. He's not afraid of anything," Randy said with a chuckle.