Medical researchers have long asked the question: Is there a connection between one’s blood type and autoimmune disease?

Clinical studies have had varied results, mostly due to the small sample sizes of each study. Though this area needs more research, this blog post will cover some of the research that has been published so far.

Study: Rheumatic Diseases and ABO Blood Types

A 2017 study in Turkey sought to find a link between particular blood types and the incidence of rheumatic disease. Rheumatic disease includes over 200 conditions that cause pain in your joints, connective tissue, tendons, and cartilage; many of these conditions are autoimmune diseases such as rheumatoid arthritis, Sjogren’s Syndrome, and systemic lupus erythematosus.

The researchers assessed 823 patients, with the following distribution of blood types: 42.5% patients had type A blood, 33.2% had type O blood, 15.4% had type B, and 8.9% had type AB. Each patient in the study had at least one of the following nine rheumatic diseases:

• Behçet’s disease
• Familial Mediterranean fever (FMF)
• Rheumatoid arthritis (RA)
• Spondyloarthropathy
• Systemic lupus erythematosus (SLE)
• Systemic sclerosis (SSc)
• Sjogren’s syndrome (SjS)
• Undifferentiated connective tissue disease
• Vasculitis

Their study found that there was a significant difference in the distribution of blood types among those with rheumatic diseases. The most common autoimmune diseases among those with type A blood were: rheumatoid arthritis, spondyloarthropathy, vasculitis, Behçet’s disease, and undifferentiated connective tissue disease.

The most common autoimmune diseases among those with type O blood were: systemic lupus erythematosus, systemic sclerosis, and Sjogren’s syndrome. The researchers also noted that SLE, SSc and SjS are the connective tissue disorders frequently observed with antinuclear antibodies (ANA). The rheumatic disease familial Mediterranean fever was also found to be most common in those with type O blood.

Those with blood type AB were observed to be the least likely to suffer from rheumatic disease. However, it should be noted that type AB blood is also the most rare blood type in general, and represented the smallest amount of patients studied.

In addition, it was found that there was a significant difference in the distribution of Rh factor in rheumatic diseases. Of those with rheumatic diseases, 92.2% patients were Rh positive and only 7.8% patients were Rh negative. However, it should once again be noted that a positive Rhesus Factor (Rh+) is also more common among the general population than a negative Rhesus Factor (Rh-).

Is there a link between autoimmune disease and blood type?

So, if you have blood types A or O, does this mean you are more likely to get an autoimmune disease? The researchers who conducted this study concluded: “…we believe that the higher incidence of different rheumatic diseases in different blood types is associated with different genetic predispositions.”

In other words, since blood type is inherited (i.e. genetic), the results of the study point to a likely connection between certain genes and the increased predisposition for developing an autoimmune or rheumatic disease.

Do you know your blood type?

I, for one, do not know my own blood type. This is somewhat ironic, since I’ve undergone many blood tests as part of my Sjogren’s syndrome diagnosis, as well as for monitoring my liver enzyme levels while taking certain medications to control my autoimmune symptoms.

I actually did ask my primary care doctor what my blood type was the last time he ordered a test, and he advised that finding out your blood type is not a common part of the blood testing routine, and thus, he didn’t know what mine was.

If you have an autoimmune disease (or multiple diseases), and you know your blood type, comment below and let us know, are your condition and blood type consistent with the results of this study?