To the Editor: Early lymphocyte development requires the orchestrated interplay of pathways to maintain genomic integrity and accurate DNA repair during the proliferative bursts associated with antigen receptor rearrangement.1 Inborn errors in replication control or DNA repair can lead to primary immunodeficiency.2 We report the case of a patient with combined immunodeficiency, facial dysmorphisms, and autoimmunity with a novel mutation in the DNA polymerase epsilon subunit 2 (POLE2) gene. POLE3 (17kDa) and POLE4 (12kDa) represent 2 additional subunits in the complex.4,5 The functional role of the POLE holoenzyme includes leading strand synthesis required for DNA replication and proofreading activity required for the repair of DNA damage and for maintenance of sequence (epigenetic) inheritance.4,5 The exact function of the POLE2 subunit is not known, but is thought to involve protein-protein interactions, including dimerization with POLE1 and influencing the C-terminal part of the catalytic subunit.