PBMAH is a rare cause of ACTH-independent Cushing syndrome accounting for less than two percent of the overall endogenous cases. Pathogenic germline variants in ARMC5 arecausative of approximately 40% (range 20-50%) of PBMAH cases, across all ethnicities, and are inherited in an autosomal dominant manner with incomplete penetrance. Two pathogenic variants, a somatic and germline, are required for PBMAH development, following the Knudson’s two hit hypothesis. Each adrenocortical nodule, in this multinodular disease, can harbour a private disease-causing variant in ARMC5. The prevalence of disease-causing variants in ARMC5 in the general population is unknown.