Mattie Stepanek, 13; wrote about living through illness

ANNAPOLIS, Md. -- Mattie Stepanek, the child poet whose inspirational verse made him a best-selling writer and a prominent advocate for muscular dystrophy treatment, died yesterday from complications of the disease. He was 13.

Mattie died at Children's National Medical Center in Washington, the hospital said.

"His example made people want to reach for the best within themselves," Jerry Lewis, national chairman of the Muscular Dystrophy Association, said in a statement.

Mattie had dysautonomic mitochondrial myopathy, a genetic disease that impaired almost all of his body's major functions, such as heart rate, breathing, blood pressure, and digestion, and caused muscle weakness.

His mother has the adult-onset form of the disease, and his three older siblings died of it in early childhood.

Mattie began writing poetry at age 3 to cope with the death of a brother. In 2001, a small Virginia publisher issued a slim volume of his poems, called "Heartsongs." Within weeks, the book reached the top of The New York Times bestseller list, the Muscular Dystrophy Association said. The book was followed by three others.