IGHE and immunodeficiency disease: In a recent study comparing five different sets of immunological investigations, Aliberti et al. were able to demonstrate that addition of IgG subtypes and lymphocyte subsets to the base investigations recommended in ERS guidelines resulted in a very significant increase in immunodeficiency diagnoses (8.9% vs. 44.6% p < 0.001) and further addition of HIV test and IgE did not increase the diagnostic yield any further [10].