MEDICINE Rare genetic disorder leaves girl unable to feel pain

Only 17 people in the United States are known to have the condition.
PATTERSON, Ga. (AP) -- Ashlyn Blocker's parents and kindergarten teachers all describe her the same way: fearless. So they nervously watch her plunge full-tilt into a childhood deprived of natural alarms.
In the school cafeteria, teachers put ice in 5-year-old Ashlyn's chili. If her lunch is scalding hot, she'll gulp it down anyway.
On the playground, a teacher's aide watches Ashlyn from within 15 feet, keeping her off the jungle gym and giving chase when she runs. If she takes a hard fall, Ashlyn won't cry.
Ashlyn is among a tiny number of people in the world known to have congenital insensitivity to pain with anhidrosis, or CIPA -- a rare genetic disorder that makes her unable to feel pain.
"Some people would say that's a good thing. But no, it's not," says Tara Blocker, Ashlyn's mother. "Pain's there for a reason. It lets your body know something's wrong and it needs to be fixed. I'd give anything for her to feel pain."
Affects specific nerves
The untreatable disease also makes Ashlyn incapable of sensing extreme temperatures -- hot or cold -- disabling her body's ability to cool itself by sweating. Otherwise, her senses are normal.
Ashlyn can feel the texture of nickels and dimes she sorts into piles on her bedroom floor, the heft of the pink backpack she totes to school and the embrace of a hug. She feels hunger cravings for her favorite after-school snack, pickles and strawberry milk.
That's because the genetic mutation that causes CIPA disrupts only the development of the small nerve fibers that carry sensations of pain, heat and cold to the brain.
"There are all kinds of different nerve cells that help us feel different sensations," says Dr. Felicia Axelrod, a professor of pediatrics and neurology at New York University School of Medicine. "You can have one sense removed, just like you can lose your hearing but still smell things."
Specialists such as Axelrod don't know how many people suffer from CIPA. As director of a treatment center that specializes in CIPA and related disorders, Axelrod has 35 patients with the disease on file. Only 17 of them are from the United States. Japan has the world's only association for CIPA patients. It has 67 members.
Discovered at 8 months
In Patterson, a rural town of 800 people in southeast Georgia, John and Tara Blocker had no idea the disorder existed before they took Ashlyn to the doctor for a bloodshot, swollen left eye when she was 8 months old.
The doctor put drops in Ashlyn's eye to stain any particles that might be irritating it. The infant smiled and bounced in her mother's lap while the dye revealed a massive scratch across her cornea.
"They put the dye in her eye and I remember the look of puzzlement on all their faces," Ashlyn's mother says. "She was not fazed by it by any means."
Tests by a geneticist led to Ashlyn's diagnosis. To have the disorder, Ashlyn had to inherit two copies of the mutated gene -- one from each parent.