EAST EARL, Pa. - Across the moonless dark of Lancaster County, where horse-drawn buggies clatter along dusty country roads and many families shun electricity, a strange blue light cuts harshly through the night.

Downstairs, flaxen-haired girls with braids read to younger children ... a mother in a traditional long print dress and white organdy cap rocks a slumbering child ... a father returning from the fields pulls up a chair to the coal-fired stove.

The scene is bathed in the glow of a single gas lamp.

Upstairs, a baby sleeps in another kind of light, in a very different world.

High-intensity blue electric rays burn down upon his crib, creating an iridescent haze that envelops the room. The lights are suspended from a heavy stainless steel canopy just inches above the child.

The baby wears only a diaper and has no blankets, just starched white sheets. Mirrors are built into one side of the crib. Fans hum loudly to keep him cool.

With his chubby cheeks and bleached blonde hair, 15-month old Bryan Martin looks like an angel in his luminous cocoon.

But Bryan is a very sick child.

The whites of his eyes are yellow and his skin is an unnatural gold.

The blue lights are saving his life.

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In the lush, green pastures of Pennsylvania Dutch country, where life revolves around the one-room schoolhouse, the farm and the church, and locals speak a distinctive German dialect, the strange blue lights beam from a handful of homes.

To the Amish and Mennonites they mean one thing — the presence of an extraordinarily rare disease that seems to cruelly target their communities, forcing afflicted children to spend 10 to 12 hours a day, undressed, under lights.

The children suffer from a genetic disorder that causes high levels of a toxin called bilirubin to build up in their bodies, resulting in severe jaundice that, if untreated, causes brain damage and death.

Bilirubin, a natural waste product from worn-out red blood cells, is normally broken down by an enzyme in the liver. If the enzyme is missing, bilirubin can be checked only by the wavelengths of blue lights. Levels must be monitored constantly. Even minor injuries or infections can cause them to rise dramatically.

The disease is Crigler-Najjar syndrome, named for two doctors who identified it 55 years ago. There are about 110 known cases of Crigler's worldwide, including about 35 in the U.S. About 20 are among the Amish and Mennonite in Pennsylvania.

There is no cure; Bryan's only hope for long-term survival is a liver transplant.

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As a Mennonite, Katie Martin embraces the teaching of her church, that sick children are gifts from God, born to foster compassion and understanding.

But nothing prepared her for the news that her firstborn, Derick, had Crigler's. Several years earlier, a nephew had suffered brain damage and died of the disease at age 3.

"I thought it was a death sentence," she said.

In the past, it usually was. But in 1990 a new clinic had just opened in Strasburg specializing in children with rare diseases. There, the Martins met a doctor who had once studied with Dr. John Crigler, who first described the disease with Dr. Victor Najjar in 1952. The doctor told them about bilirubin levels and the dangers of kernicterus, the brain disorder that killed their nephew.

Bring the baby back for blood tests every month, the doctor told them.

And keep him under blue lights.

So the Martins — who are unrelated to Bryan Martin — took their yellow baby back to their 140-acre dairy farm in Mifflinberg and embarked on a life of testing, monitoring and lights.

Floyd, who also works as a welder, fashioned a stainless steel-framed canopy to hold the lights over his son's bed. He learned all he could about phototherapy, as the blue light treatment is called. As the boy grew, Martin made bigger, more sophisticated frames. When his next child, Amy, was born, he made another set of lights. When their three cousins across the hill were stricken, he made more.

Today, Floyd Martin's blue light beds, which cost about $1,000, are sought by Crigler families all over the world.

The Martins, old-order Mennonites, have electricity and a phone, but there is no computer, television or radio in their house. They travel by horse and buggy, except for emergencies when they hire a driver.

They had no moral qualms about using electric lights, as some more conservative families do.

But the disease forced other compromises, like accepting state insurance for their sick children, even though church rules forbid any form of government help. Generally, the church pays for all medical care.

"The hardest thing," says Katie Martin, a slender woman of 37 with a pale, thin face and dark brown eyes, "was to hear them cry on cold winter nights and not just be able to wrap them in a blanket or curl up in our bed."

She is standing in the brightly lit cow barn, overseeing the noontime milking of 65 Holsteins. Derick, now a strapping young man of 17, hauls long milking tubes along a motorized pulley. Amy, 15, attaches them to the cows.

The teenagers radiate sturdiness and health. Still, their mother eyes them nervously.

For years she has worried about bilirubin levels. She has cajoled her children back under the lights on the nights they crawled out, complaining about the heat. She has nursed them through gallbladder operations, and debilitating fatigue  [ send green star]