Impact of Month of Birth on the Risk of Development of Autoimmune Addison's Disease

Context: The pathogenesis of autoimmune Addison's disease (AAD) is thought to be due to interplay of genetic, immune, and environmental factors. A month-of-birth effect, with increased risk for those born in autumn/winter months, has been described in autoimmune conditions such as type 1 diabetes and autoimmune thyroid disease. Objective: Month-of-birth effect was investigated in 2 independent cohorts of AAD subjects. Design, Setting, and Patients: The monthly distribution of birth in AAD patients was compared with that of the general population using the cosinor test. A total of 415 AAD subjects from the United Kingdom cohort were compared with 8 180 180 United Kingdom births, and 231 AAD subjects from the Polish cohort were compared with 2 421 384 Polish births. Main Outcome Measures: Association between month of birth and the susceptibility to AAD. Results: In the entire cohort of AAD subjects, month-of-birth distribution analysis showed significant periodicity with peak of births in December and troug...