Irving boy, 15, dies after illness Sister, 13, succumbed to same unexplained ailment 10 days ago 08/29/2002 By LEE POWELL / The Dallas Morning News IRVING - A 15-year-old Irving boy has died, 10 days after his younger sister succumbed to a still-unexplained illness. Matthew Johnson died Wednesday at Children's Medical Center, according to the Dallas County medical examiner's office, two weeks after he slipped into a coma. Hospital officials have declined to release information about the children, citing their parents' wishes. An autopsy was performed on Rachel Johnson, the boy's sister, but its findings have yet to be...