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There are many avenues for interdisciplinary collaboration within rheumatology, as our specialty encompasses every organ system and diseases with protean manifestations. The intersection of rheumatology and immunology is well known and has become increasingly important, given the association of autoimmune conditions with many of the primary immunodeficiency syndromes. This intersection was highlighted today at ACR by two excellent abstracts.
The first was presented during the plenary session and was the result of a multi-center collaboration – Screening of patients with adult-onset idiopathic polyarteritis nodosa for deficiency of adenosine deaminiase 2 (DADA2) (abstract #2790). DADA2 is a rare genetic disorder associated with inflammation in various tissues, including vasculitis and risk of stroke. In particular it is known to be associated with polyarteritis nodosa (PAN). The investigators of this study looked at the prevalence of DADA2 in patients with presumed idiopathic PAN. 117 patients with idiopathic PAN (all negative for hepatitis B) were screened for mutations in ADA2 and 6.8% had rare missence variants in ADA2. While there were no clinical differences between PAN patients with or without these mutations, this may have implications in screening family members as well as for treatment, as TNF inhibitors are often used to treat DAD2, but are not often used for PAN.
The second abstract (#2838), presented by Kevin Byram, was a study examining what are the most common primary immunodeficiency (PID) syndromes associated with vasculitis. They did this by querying the USIDNET, a national consortium of PID patients, for vasculitis cases. 76 patients with vasculitis (out of 4,888 PID cases) were identified. The most common PID associations were common variable immunodeficiency (38%) and Wiskott-Aldrich Syndrome (26%). Interestingly, CNS vasculitis was the most common specific vasculitis syndrome identified (14%), and vasculitis cases were reported to be present before or at the time of PID diagnosis ~50% of the time. While vasculitis is an uncommon complication of PID, it is important for rheumatologists to be aware of this entity.