8393 Low Polygenic Risk Score For Autoimmune Addison’s Disease Identifies Misdiagnosed Cases of Monogenic Primary Adrenal Insufficiency

Abstract Disclosure: M. Aranda Guillen: None. I. Botusan: None. V. Fernando: None. E. Røyrvik: None. A. Bøe Wolff: None. S. Johansson: None. E.S. Husebye: None. S. Bensing: None. O. Kampe: None. D. Eriksson: None. Background: Primary adrenal insufficiency (PAI) is sometimes misdiagnosed as autoimmune Addison's disease (AAD), affecting clinical management and genetic counselling. We tested a polygenic risk score (PRS) for AAD (PRS14AAD) as a tool to reevaluate disease etiology and identify patients misdiagnosed with AAD. Methods: We calculated the PRS14AAD in a cohort of patients diagnosed with AAD but lacking 21-hydroxylase autoantibodies (n=124). Patients with low genetic susceptibility to AAD were selected for whole-genome sequencing to detect potential monogenic causes (n=35). Results: Among the 35 patients, monogenic PAI was diagnosed in 5 (14%) and suspected in 3 additional cases (9%). Three out of the 5 patients diagnosed with monogenic PAI developed the disease in adulthood, indicating late-onset monogenic disease associated with hypomorphic genetic variants. Conclusion: A PRS for AAD can help identify potential monogenic cases, regardless of the age at diagnosis. Early identification of the underlying cause of PAI enables accurate management and correct genetic counselling. Presentation: 6/2/2024