The doctor who makes house calls also collaborates with English and American geneticists studying some of the rarest diseases on Earth. Some occur at much higher levels among the Amish, Mennonites and other closed communities that don’t allow marriage to outsiders. This prohibition increases the likelihood that when a rare, disease-causing mutation appears in the community, it will take root and pass from generation to generation.

Scientists use a special term, “the founder effect,” to explain how some variations in the human genetic sequence appear more often in groups that are geographically or culturally isolated.

It has taken DeLine and his staff years to gain the trust of Plain People, some of whom are wary of medicine and technology. Often, they fear that going to a hospital or clinic will mean surrendering the decision-making to doctors who neither respect their beliefs nor understand their financial limitations.

DeLine, not a religious man himself, accommodates the beliefs of patients and parents; he has always viewed them as the ultimate decision-makers. As a result, the clinic has become a magnet for Plain People. Some travel eight hours from Missouri or Iowa just to see him.

In a rural Wisconsin village, the doctor makes house calls — and sees some of the rarest diseases on Earth | Milwaukee Journal Sentinel