CTLA4 and autoimmune lymphoproliferative syndrome due to CTLA4 haploinsufficiency: The patient was further investigated for combined immunodeficiency and whole exome sequencing revealed a novel heterozygous missense variant in <i>cytotoxic T lymphocyte antigen 4</i> (<i>CTLA4</i>), leading to a diagnosis of CTLA-4 haploinsufficiency with autoimmune infiltration (CHAI).<h4>Conclusion</h4>This case demonstrates that autoimmune disease may be the presenting feature of primary immunodeficiency and should be appropriately investigated prior to the commencement of immunotherapy.