Multiple Autoimmune Syndrome (MAS)

Multiple autoimmune syndrome is when at least three autoimmune diseases are present in the same patient.  

According to Cojocaru et al. (2010), additional autoimmune diseases frequently develop in patients who already have at least one autoimmune disease (full article).  Cojocaru groups the autoimmune clusters into three types:

i. type 1 MAS includes myasthenia gravis, thymoma, polymyositis and giant cell myocarditis

ii. type 2 MAS includes Sjögren's syndrome, rheumatoid arthritis (RA), primary biliary cirrhosis (PBC), scleroderma, and autoimmune thyroid disease

iii. type 3 MAS groups together autoimmune thyroid disease, myasthenia gravis and/or thymoma, Sjögren's syndrome, pernicious anemia, idiopathic thrombopenic purpura (ITP), Addison's disease, type 1 diabetes mellitus, vitiligo, autoimmune hemolytic anemia (AIHA), systemic lupus erythematosus (SLE), and dermatitis herpetiformis.

Since I have autoimmune thyroid disease and Sjögren's disease, I am potentially either type 2 or type 3.  This is important since I know which autoimmune diseases I am more likely to develop should I acquire an additional disease.