Genetic studies link JIA subtypes to adult diseases, show uniqueness of systemic disease
FROM ANNALS OF THE RHEUMATIC DISEASES
“[sJIA] is characterized by prominent systemic inflammation and has a rare adult-onset counterpart; and undifferentiated arthritis includes arthritis that does not fit into any single category,” the authors wrote, adding that the “unique clinical characteristics of sJIA suggest that it is distinct from other forms of JIA, leading to the contention by some that sJIA should be separated from other forms of JIA and labeled as an autoinflammatory disease.”
The investigators carried out SNP genotyping on 982 children with sJIA in the United States, United Kingdom, Germany, Turkey, Italy, Brazil, Argentina, Canada, and Spain, along with 431 healthy children without sJIA who came from the same countries. A total of 7,579 control patients also underwent genotyping. Ultimately, 770 sJIA and 6,947 control subjects completed the study. sJIA was then compared with other JIA subtypes by using weighted genetic risk scores.
Comparison of the data sets for sJIA with those for the combined categories of RF-negative polyarticular JIA and oligoarticular JIA, as well as for the individual category of RF-positive polyarticular JIA, showed that sJIA has a distinct genetic architecture that separates it from those JIA categories, providing further evidence that sJIA should be classified separately from other forms of JIA and, potentially, treated differently as well.
According to Dr. Thomson, the finding “provides important evidence that sJIA should be considered a unique disease with its own specific disease mechanisms.” Dr. Thomson explained that “knowing more about the genetic risk factors of this disease might give a greater understanding of the disease processes involved in this condition and ultimately lead to novel therapies for this severely disabling disease.”
Funding for the first study was provided by the Wellcome Trust, the National Institutes of Health, the Doris Duke Charitable Foundation, the Medical Research Council, the Canadian Institutes of Health Research, the Liaison Committee between the Central Norway Regional Health Authority and the Norwegian University of Science and Technology, the Juvenile Diabetes Research Foundation International, and the Texas Scottish Rite Hospital for Children. Funding for the second study was provided by intramural research programs of the National Institute of Arthritis and Musculoskeletal and Skin Diseases and the National Human Genome Research Institute, individual NIH grants, and grants from charitable foundations, advocacy organizations, and the governments of individual researchers’ countries. Dr. Thomson did not report any relevant financial disclosures; however, a number of coauthors reported potential conflicts of interest.
