Antifibrillarin Antibodies in Systemic Sclerosis
Welcome to the June edition of #chatJRheum.
In the past few months, I have highlighted articles on temporal arteritis, rheumatoid arthritis and lupus. This month’s article of interest is on the hot topic of scleroderma associated antibodies.
In this study, 3 large systemic sclerosis cohorts from Canada, the United States and Australia collaborated to examine a total of 1506 patients, of which 52 had antifibrillarin antibodies (U3-RNP). The clinical characteristics found to be associated with antifibrillarin antibody included:
- Antifibrillarin antibody was more likely to be associated with diffuse disease, GI involvement, and pulmonary hypertension.
- Patients with antifibrillarin antibodies had decreased survival, with variable causes of death. The authors hypothesize GI involvement may play a role, given that malabsorption is a poor prognostic factor.
- The study uncovered a possible association between high rates of antifibrillarin antibodies among indigenous North American (4/39), but not Australian (0/8) ethnic patients. It confirmed previously noted higher frequency in patients of African descent. However, these associations should be interpreted with caution due to the small sample size of these ethnic subgroups.
Strengths of this article include antibody measurement among these 3 cohorts analyzed using the same immunoassay kit, ensuring homogeneity and reproducibility. Also, while the patient population may be predominantly Caucasian (83%), it is representative of many patient populations in these countries.
I selected this article because of its direct impact on the care of our patients, and it fills an ongoing need for further robust information on this topic. As these antibody measurements become more widely used in clinical practice, information from such a collaborative effort is of great help in further defining a very rare disease, guiding patient counselling, and directing clinical practice.
A note to the authors (if you are reading this): please keep these studies coming for the remaining antibodies on the panel!
- Dr. Sarah Troster, Forum Editor