TRENTON, N.J. (AP) âÄî In a new and disturbing twist on the obesity epidemic, some overweight teenagers have severe liver damage caused by too much body fat, and a handful have needed liver transplants. Many more may need a new liver by their 30s or 40s, say experts warning that pediatricians need to be more vigilant. The condition, which can lead to cirrhosis and liver failure or liver cancer, is being seen in kids in the United States, Europe, Australia and even some developing countries, according to a surge of recent medical studies and doctors interviewed by The Associated Press. The American Liver Foundation and other experts estimate 2 percent to 5 percent of American children over age 5, nearly all of them obese or overweight, have the condition, called nonalcoholic fatty liver disease. “It’s clearly the most common cause of liver disease,” said Dr. Ronald Sokol, head of public policy at the liver foundation and a liver specialist at Children’s Hospital and University of Colorado Denver. Some experts think as many as 10 percent of all children and half of those who are obese may suffer from it, but note that few are given the simple blood test that can signal its presence. A biopsy is the only sure way to diagnose this disease.