astonishing medical mystery we first heard about from our denver station, kmgh. A brother and sister so severely allergic to the cold, even getting close to the air conditioner could be... See More
astonishing medical mystery we first heard about from our denver station, kmgh. A brother and sister so severely allergic to the cold, even getting close to the air conditioner could be life-threatening. Abc's linsey davis is here with their story. Reporter: This is something so unusual, so rare, the family actually had to go to more than half a dozen doctors before their children could be diagnosed. Imagine being a child who can't play in the snow or go outside when it's cold or even eat ice cream. That's the life of a very small group of people who are actually allergic to the cold. Connor and taylor frankenfeld's days to play outside are numbered. All because of a peculiar, life-threatening allergy. There is sometimes that i feel like I'm not an ordinary kid. Reporter: The 5-year-old and 8-year-old brother and sister are both allergic to the cold, a condition that could actually kill them. When it first started, it started in the diaper area. They told us diaper rash. It went from diaper rash to a staph infection. Then, it went to winter itch. Reporter: Connor was 3 years old when the frankenfeld first noticed the painful rash. Then, it got worse. One day after playing in the snow, connor's whole arm started to swell. I tell the doctors, don't think I'm nuts. I had one doctor tell me I was nuts. There's no blood test for this. Reporter: So, dr. William landing tested them by putting an ice cube on their arm for three minutes to test their reaction. He iged both children with cold urticaria, a rare allergy to the cold. I've had five or six cases in my career. I freak out when I see the weather starting to cool down. Reporter: Taylor has it so bad, she went into shock from walking under an air conditioning vent. I finally feel my throat start to feel funny.Was really scared. I thought I was going to die. Reporter: A scary diagnosis, for such young kids. Moving away from colorado won't help the matter. It's not just the weather that bothers them. Cold floors, ice water, air conditioning. Things you'll find anywhere in any climate.
This transcript has been automatically generated and may not be 100% accurate.