The types do not change within families. A family with joint hypermobility EDS will not produce a child with vascular EDS, for instance. It's estimated that 1 in 5,000 people have EDS, which can afflict children or adults of any race and either gender.

Hansen's daughter, April Atwood, inherited his Ehlers-Danlos, while his son did not. But she has been affected in markedly different ways than her father. Her mother, Denise Groves, suspected the girl had inherited the condition because she bruised so easily. The first symptom appeared at age 14, when she got cramps that wouldn't go away. At Primary Children's Medical Center, doctors found that her area of vulnerability is her intestinal tract, which ruptures and bleeds.

"The doctor told me it was like sewing up Jell-O," Groves says.

At that time, she was hospitalized for six weeks fighting infection from the rupture.

But her mother says that in many ways Atwood has been lucky. She has been able to go everywhere. "She was on the swim team, because it's low-impact," Groves says of her daughter. "Running or team sports would have been out of the question."

Lacy Chambers, on the other hand, gave up gymnastics and violin because of the stress on her joints. With hypermobile joints, children are sometimes encouraged to stay home from school to avoid injury, and her mom, Dawn Lynn Heuer, briefly home-schooled her for that reason.

When Atwood was younger, she bruised so easily that her mother was afraid officials would "grab me for child abuse. It happens to families." Even a friendly touch on the arm can leave finger-shaped bruises.

Groves learned vigilance with her daughter. It was hard to differentiate between a stomach bug and a crisis, but if intense cramping lasted very long, they'd head for the hospital. Groves remembers car rides where she was shaking hard, worried that the emergency room doctor would, like so many others, be unfamiliar with Ehlers-Danlos or know only of one type. "There are certain tests you have to be careful with," she says. "You can't shove things down her throat or start poking. The tissue is so fragile it can rupture easily. A little lack of knowledge could kill her."

During Atwood's first bout in the hospital, the doctors took a tissue sample and sent it to an EDS specialist out of state, who checked it for the genetic markers and confirmed the diagnosis, something only possible with vascular EDS. The other types are diagnosed based on family history and symptoms, says Dr. Mark Lavallee, a national expert on EDS from South Bend, Ind., who is board-certified in family medicine, sports medicine and nonoperative orthopedics.