Biallelic PGM3 mutations in humans result in a range of immunological disease phenotypes, from Hyper IgE syndrome (HIES)-like phenotypes to combined immunodeficiency (CID) presentations and even severe combined immune deficiency (SCID)-like diseases with lymphopenia, syndromic features such as skeletal abnormalities, and developmental delay (2–15). The gene discussed is PGM3; the disease is combined immunodeficiency.