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They also found antibodies against a protein called rheumatoid factor and others that help with blood clotting.

My mother’s conditions are not hereditary, nor are they related to migraine, but neurologists still want to test my blood for rheumatoid factor and other traces of autoimmune disease.

Blood tests check for specific markers of the disease, such as a substance called rheumatoid factor, and Zieman's results were negative, something that occurs occasionally.