Founder Effect among the Amish

"The Amish make up only about 10 percent of the population in Geagua County in Ohio, but they're half of the special needs cases. Three of the five Miller children, for example, have a mysterious crippling disease that has no name and no known cure.

...The three Byler sisters were all born with a condition that has no cure and mysteriously leads to severe mental retardation and a host of physical problems. Last year, doctors figured out the girls have the gene for something called Cohen Syndrome; there are only 100 known cases worldwide. 

..."Nobody knew it was around here and we found, what, 20 to 30 cases in this area now that they didn't realize. Nobody knew about it," says Erwin Kuhns.

...The genetic problems come down to something called the "founder effect" because the nearly 150,000 Amish in America can trace their roots back to a few hundred German-Swiss settlers who brought the Amish and Mennonite faiths to the United States in the 18th century. Over generations of intermarriage, rare genetic flaws have shown up, flaws which most of us carry within our genetic makeup but which don't show up unless we marry someone else with the same rare genetic markers.

...While 60 Minutes Wednesday was in Ohio, Dr. Wang [a pediatrician hired by the community] made a house call to check on the Miller children. Bobby Junior, the sickest, can't tell Wang what's bothering him because he can't even talk.

And the doctor was treating these challenging cases under the most rudimentary conditions since Amish custom prohibits electricity. Still, he doesn't complain. In fact, he calls the heritage beautiful and says, "We are not come here to change them."

..."I knew as soon as I had the third one, I knew," [the mother of the Byler sisters] says. "They kept telling me, 'No, she's OK.' No, she wasn't. I could hear by her cry that she was gonna be like the others. Their cry is different. You can tell. After you've lived with it that long, you know."

Now, when she needs to go to the doctor, she wheels the girls into her van. She's left buggy rides, and the whole Amish lifestyle, behind. But the price was being shunned forever by the community, as well as her ex-husband and her two healthy adult children.

Irma's now tuned in to the 20th century, and Iva's plugged into the 21st. Using a genealogy Web site, she's figured out she and her ex-husband were distantly related, something that appears to be common among the Amish.

"I don't think the Amish really understand that it's a genetic disorder that causes the handicapping condition," Byler says.

The Amish think it is God's will; "Gottes Wille" is how they describe it."

-CBS News