Table of Contents
Genetic Factors
Genetic factors may play some role in RA either in terms of increasing susceptibility to developing the condition or by worsening the disease process. The main genetic marker identified with rheumatoid arthritis is HLA (human leukocyte antigen).
A number of HLA genetic forms called HLA-DRB1 and HLA-DR4 alleles are referred to as the RA-shared epitope because of their association with rheumatoid arthritis. These genetic factors do not cause RA, but they may make the disease more severe once it has developed. Genetic variations in the HLA region may also predict drug treatment response to etanercept and the disease-modifying anti-rheumatic drug methotrexate.
Environmental Triggers
Infections. Although many bacteria and viruses have been studied, no single organism has been definitively identified as a trigger for RA. Higher than average levels of antibodies that react with the common intestinal bacteria E. coli have appeared in the synovial fluid of people with RA. Some researchers think they may stimulate the immune system to prolong RA once the disease has been triggered by some other initial infection. Other potential triggers include Mycoplasma, parvovirus B19, retroviruses, mycobacteria, and Epstein-Barr virus.
Review Date: 02/16/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M.,
Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
