Patients with common variable immunodeficiency (CVID) showed a large shift in the microbiota (reduced abundance of Actinobacteria and Firmicutes and increased abundance of Gammaproteobacteria) which was particularly pronounced in patients with undetectable serum IgA and also found in patients with selective IgA deficiency (99–101). This evidence concerns the gene CD79A and common variable immunodeficiency.