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. This evidence concerns the gene CTLA4 and immune system disorder.