Supplementary Material for: Prevalence of Autoantibodies in patients with Hereditary Alpha Tryptasemia

Introduction: Hereditary alpha-tryptasemia (HT) is associated with postural orthostatic tachycardic syndrome (POTS), hypermobile Ehlers Danlos Syndrome (hEDS), and mast cell activation syndrome (MCAS). While POTS, hEDS and MCAS have all demonstrated increased prevalence of autoimmunity, this has not been investigated in HT populations. Our objective was to describe the prevalence of autoantibodies in individuals with HT.
Methods: We retrospectively studied a cohort of patients with positive genotyping for HT at a tertiary care allergy clinic. Demographic data including previous autoimmune history and autoantibody serologies were extracted on chart review. A literature search was conducted to determine the prevalence of specific autoimmune and autoantibody prevalences in the general population. We compared the proportions of autoantibody positivity and established autoimmune diseases in our cohort of HT individuals against those in general populations.
Results: We identified 101 patients with HT. Median age was 43 years (range 15-75) and most were female (87/101; 86.1%). Prevalence of self-reported drug hypersensitivity was 52/101 (52.5%) patients. The proportion of individuals with HT with positive tTG antibody (3/61, 4.9%) was significantly higher than that reported in the general population (133/16667, 0.8%) (p<0.001). The prevalence of SLE (1/101, 1%) and celiac disease (5/101, 5%) in our cohort were found to be significantly higher than the prevalence in the general population [194/96996, 0.2% (p=0.035) and 26/2845, 0.9% (p<0.001), respectively].
Conclusion: Patients with HT have increased prevalence of celiac disease, SLE and positive anti-tTG serology as well as self-reported drug hypersensitivity, relative to general populations.