We demonstrated that an algorithm using serum biomarkers MILR1, LILRB4, IL10, IL12RB1, and CD83 identified by targeted serum proteomics could classify immune dysregulation in CVID in a discovery cohort and in our independent testing cohort, providing a first step towards the development of a screening tool for immune dysregulation in CVID. The gene discussed is MILR1; the disease is common variable immunodeficiency.