An immune-mediated condition, meaning that it involves the occurrence of disease in organs as the result of an abnormally regulated immune system. The classic IgG4-RD patient is a middle-aged to elderly individual – more likely to be male than female. In rare cases, the disease also affects children. Some patients with IgG4-RD have disease in only one organ. Others, however, have diseases that affect multiple organs at the same time. Learn more.