My rheumatologist believes that I may have a combination of rheumatoid arthritis (RA) and ankylosing spondylitis (AS). I have had a positive rheumatoid factor (RF) test and I present classic examples of inflammation and damage in joints commonly associated with RA including in the proximal interphalangeal (PIP) and metacarpophalangeal (MCP) joints in both hands. Add to that list, symmetrical joint presentation in the wrists, shoulders, hips, and knees along with fatigue and it seems like RA. At the same time, my rheumatologist noted limited spinal mobility and many problems with my ankles and Achilles’ tendons which are common with AS. My first autoimmune symptom, which occurred years before joint problems, was inflammatory uveitis in both eyes. While Achilles tendon problems and uveitis can be associated with RA, they are more commonly seen in AS patients. But a test for HLA-B27, a common genetic test related to ankylosing spondylitis (AS), was negative. These blood tests are not 100% accurate and the official diagnosis in my chart is RA (diagnosis code 714).
Muddying the water is the fact that I have been through a slew of RA treatments over the past four years in an effort to find a combination that works for the long term. I’m currently on Actemra infusions and now going back to add leflunomide (Arava) in an effort to capture the earlier success with Actemra. While many RA patients find relief from the most common treatments like methotrexate, Enbrel, and Humira, it seems to elude 30-40% of patients.[i] Every person seems to respond differently to various medicines and doses.
This personal evidence leads me to believe that there may be different sub-types of RA. In a recent conversation at the RA site on HealthCentral, the notion of sub-types of RA was mentioned. We already know that there are different types of inflammatory arthritis including RA, AS, psoriatic arthritis.[ii] And each of these diseases presents different patterns and may be treated with similar and/or different medications. But there seems to be a lack of scientifically defined sub-types of RA.
According to researchers from the Netherlands, “Rheumatoid arthritis (RA) is a heterogeneous disease with unknown cause.“[iii] Differences in genetic expressions of RA patients were seen by these researchers lending some credence to a genetic link to sub-types of RA. In an earlier study of the genetics of RA in 1989, researchers found a gene called HLA-DR was found in 83% of 149 patients with classical or definite RA.[iv] But no explanation is given for the 17% of RA patients who did not show the gene. In 2010, a group of researchers found four genetic sub-types of RA.[v] Japanese scientists found genetic differences at the molecular level. They stated, “Data from genome-wide screening, transcriptional profiling, and animal models indicate that RA consists with heterogeneous disease subsets.”[vi] Some researchers even found different emotional responses in RA patients.[vii]
While the causes of RA are not completely evident, most scientists suspect a combination of factors including genetic and environmental (see earlier post on the triggers of RA). Scientists are now beginning to unravel the complexities of RA and find that there may actually be a variety of sub-types of the disease. I hypothesize that future research into RA and other autoimmune diseases will reveal that genetics and environmental factors impact the way individuals present symptoms and respond to treatments. This knowledge may lead to definitions of RA sub-types and better treatments in the future. In the meantime, I’ll keep experimenting with treatments in order to find a combination that works.