The location of TRAF1/C5 gene on chromosome 9 plays an important role in multiple autoimmune diseases like type 1 diabetes and systemic lupus erythematosus (SLE), scientists have revealed.
It is known that TRAF1 (Tumour Necrosis Factor-receptor associated factor 1) and C5 (complement component 5) are both immune related genes, lying adjacent to one another on chromosome 9 at location q33-34. It is believed that both these genes are essential in the onset and/or perpetuation of the inflammatory process.
Earlier, the TRAF1/C5 gene was proved to be a genetic risk factor for rheumatoid arthritis. However, in the current study, the researchers successfully established a further link between the gene locus and the presence of autoantibodies (antibodies against antigens naturally occurring in the human body commonly found in patients with immune disorders).
A number of autoimmune disorders are likely to coexist within a given family as well as an individual. This suggests that there can be a common genetic pathway, which is something that the researchers were keen to investigate.
In the current study, genotyping of 735 type 1 diabetes patients and 746 SLE patients from Spain and The Netherlands identified a significant association of one part of the TRAF1/C5 gene with type 1 diabetes and SLE.
For testing how reliable this finding is, researchers replicated the test in a homogeneous patient population originating from Crete, where an increase in the same part of the TRAF1/C5 gene was also observed when compared to respectively matched controls.
"The results of our study have shown that the TRAF/1C5 gene locus may have an important role in multiple autoimmune diseases. We hope that further study will give an insight into potential shared genetic pathways across autoimmune disorders and may even stimulate innovation into novel therapeutic targets in the future," said lead researcher, Ms Fina Kurreeman of Leiden University Medical Center in The Netherlands.
Also, a further joint analysis of all type 1 diabetes and SLE patients patients yielded a common odds ratio of 1.19 and 1.22 respectively, which suggested that this genetic risk factor has modest effect sizes in these diseases.
The study was presented at EULAR 2008, the Annual Congress of the European League Against Rheumatism in Paris, France.