Unwanted inheritance:  The family legacy of autoimmunity and arthritis

Many of you with arthritis have likely asked the question - is the reason that I have arthritis linked to my family history and genetic make-up? I frequently ask this one question myself because of my strong family history of autoimmune disease.

Researchers from Cincinnati Children’s Hospital are trying to answer this question. A Juvenile Rheumatoid Arthritis Affected Sib Pair registry was launched in 1995 and is studying affected siblings with Juvenile Rheumatoid Arthritis (refer to sources). The results to date support the hypothesis that several genes influence susceptibility to JRA. The notion is that common genetic regions could contribute to a shared predisposition to overall autoimmunity.

I smiled as I heard these study results at a recent Childhood Arthritis and Rheumatology Research Alliance (CARRA) conference. I smiled because this was the exact prototype of my family. My immediate and extended family has been plagued with a range of autoimmune diseases - psoriasis, asthma, allergies, thyroid disease, and myself with Juvenile Rheumatoid Arthritis. Does this story sound familiar?

Lupus, another autoimmune disease has a strong family association. Familial cases are reported in approximately 10% of the lupus population. The most studied family association has been in twins. Identical and fraternal twins were part of this study. If one identical twin (identical genes are shared) had lupus, the prevalence of the other twin developing lupus was more than two thirds or 69%. In fraternal twins (some genes that are shared but not identical), the other twin would have a 5% chance of developing lupus. Genetics must come into play because the chance of developing lupus is so much higher in identical twins. However, Lupus is not associated to genetic factors alone because if this were the second identical twin would get Lupus 100% of the time, which is not the case. Therefore, researchers are now theorizing that lupus is triggered by both genetic and environmental factors and the complex interplay of both these factors.

These are interesting studies, which should prove helpful in the coming years in identifying new therapies. Research of all types of arthritis, including childhood arthritis, is a key area of CAPA support. With sufficient funding for important research like this, we can hope that some day parents and parents-to-be can feel confident that they will not pass the legacy of arthritis to their children.

Sources:

A genome-wide scan for juvenile rheumatoid arthritis in affected sib pair families provides evidence of linkage

Juvenile rheumatoid arthritis affected sib pairs: extent of clinical phenotype concordance

Genetics & Lupus