Information for Patients

An autoimmune disorder is a condition that occurs when the immune system mistakenly attacks and destroys healthy body tissue. There are more than 80 different types of autoimmune disorders.

Normally the immune system’s white blood cells help protect the body from harmful substances, called antigens. Examples of antigens include bacteria, viruses, toxins, cancer cells, and blood or tissues from another person or species. The immune system produces antibodies that destroy these harmful substances.

In patients with an autoimmune disorder, the immune system can’t tell the difference between healthy body tissue and antigens. The result is an immune response that destroys normal body tissues.

What causes the immune system to no longer tell the difference between healthy body tissues and antigens is unknown. One theory is that some microorganisms (such as bacteria or viruses) or drugs may trigger some of these changes, especially in people who have genes that make them more likely to get autoimmune disorders.

Connective tissue diseases (CTD) or systemic autoimmune diseases (SADs) as they are known today are a group of chronic inflammatory conditions with autoimmune aetiology with few treatment options and difficult diagnosis. Their major common feature is the presence of unspecific autoantibodies in serum. Three diseases primarily represent the SADs: systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and systemic sclerosis (SSc) that show extensive overlap in their presentation. Several other entities and syndromes have extensive clinical overlap with these, where mixed connective tissue disease (MCTD), primary Sjögren’s syndrome (SSj) and the primary antiphospholipid antibody syndrome (PAPS) are very relevant examples. While as separate clinical entities each of these diseases is rare, together they make up to close to 1% of the general population. In addition there are individuals who do not fulfil the clinical criteria or who do not share all the features of a given clinical entity and live for years as undifferentiated cases. These diseases are the focus of our attention in PRECISESADS.