Juvenile dermatomyositis has some similarities to adult dermatomyositis and polymyositis. It typically affects children ages 2 to 15 years, with symptoms that include weakness of the muscles close to the trunk of the body, inflammation, edema, muscle pain, fatigue, skin rashes, abdominal pain, fever, and contractures. Children with juvenile dermatomyositis may have difficulty swallowing and breathing, and the heart may also be affected. About 20 to 30 percent of children with juvenile dermatomyositis develop calcium deposits in the soft tissue. Affected children may not show higher than normal levels of the muscle enzyme creatine kinase in their blood but have higher than normal levels of other muscle enzymes. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.