It's not unusual for 5-year-olds to be picky eaters, but not many would turn down a juicy double-decker hamburger for powdered milk.

Ryan Merrill is the exception but not by choice.Ryan, a son of Ronald and Andria Merrill, Bountiful, suffers from maple syrup urine disease. He's missing an important enzyme that separates the protein throughout the body.

Without the enzyme, the protein would accumulate in the brain, killing essential cells. The result could be death.

That's where the special milk plays an important role. To build up his enzymes, every day Ryan is required to drink MSUD Diet Powder, shipped from Chicago.

Fruits and vegetables and specially ordered low-protein products are also part of his daily diet which no doubt irritates the child, who has the same cravings as other youngsters who love family outings to hamburger outlets.

"When we go to McDonalds, Big Macs are out, but he can have french fries," his mom said. "He can also have certain cereals, but

only a fourth of a cup a day. His diet is specifically premeasured each day to ensure he receives the right quantity of protein."

It's a tedious regimen Ryan's been on since his rare disease was first diagnosed when he was 6 weeks old. His mother said most children who suffer from the disease die within two weeks. If they live longer, they are often severely mentally retarded.

The Bountiful tyke isn't, but he's had his share of problems. Because his ligaments don't grow with his bones, he's had to have the ligaments surgically lengthened twice first when he was age 3.

A year ago he got the stomach flu and was unable to tolerate his life-saving milk. He was comatose for three days.

"Right now he's happy and healthy, but can't walk as well as a normal child. And developmentally, he's about a year behind," Andria Merrill said.

That doesn't stop the precocious child from tormenting his sisters, ages 1 and 2. "He's a typical big boy who hates baths and is horrible with his sisters. He's always smiling even when he's teasing his sisters."

The Merrills hope their towheaded, freckled-faced child will continue to thrive despite the life-threatening disease, for which there is no cure.

But his well-being could depend on the generosity of Utah residents.

When a disagreement arose with one insurance company over payment of the milk product, the Merrills sought coverage with another. "But the (second) company misrepresented itself and we have since learned that Ryan will not be covered because he has a pre-existing condition," Merrill said.

And the Merrills are unable to bear the full cost of their son's milk and medical expenses. The milk, which now costs $7 a day, will be more expensive in the future as Ryan's growing body needs more nourishment.

And that's the least of their expenses. Ryan has regular lab work, and is hospitalized three to 10 times a year when he becomes ill. "It's an emergency every time he goes to the hospital," his concerned mother said. The first four months of his life, the child's medical and milk bills amounted to $150,000.

Because the costs to keep Ryan alive aren't likely to diminish in the future, friends of the family have established a medical trust fund. Donations can be sent to the Ryan Merrill Trust Fund, Zions First National Bank, P.O. Box 422, Bountiful, UT 84010.