CONCLUSIONS: The convergence of CML, bullous pemphigoid, and PLA2R-positive MGN in CTLA-4 haploinsufficiency broadens the clinical phenotype and underscores the importance of considering inborn errors of immunity in young adults with refractory, multisystem autoimmunity and hematologic abnormalities. The gene discussed is PLA2R1; the disease is bullous pemphigoid.