Definition of Autoimmune Diseases

Autoimmune diseases remain among the most poorly understood and poorly recognized of any category of illnesses. Individually, autoimmune diseases are not very common, with the exception of thyroid disease, diabetes, rheumatoid arthritis, and systemic lupus erythematosus (SLE). However, taken as a whole, they represent the fourth-largest cause of disability in Europe and the United States.


The term "autoimmune disease" refers to a varied group of more than 80 serious, chronic illnesses that involve almost every human organ system. It includes diseases of the nervous, gastrointestinal, and endocrine systems as well as skin and other connective tissues, eyes blood, and blood vessel. In all of these diseases, the underlying problem is similar - the body's immune system becomes misdirected, attacking the very organs it was designed to protect.

Symptoms vary widely, notably from one illness to another, but even within the same disease. And because the diseases affect multiple body systems, their symptoms are often misleading, which hinders accurate diagnosis. To help people live longer, healthier lives, a better understanding of these diseases is needed, as well as providing early diagnosis and treatment. Reliable diagnostic tools are most important for an early and exact diagnosis.