Immunologic phenotype of TACI-deficient patients. (A) CD19⁺ B-cell percentages of lymphocytes and IgD⁺IgM⁺CD27⁻, IgD⁻IgM⁺CD27⁺, and IgD⁻IgM⁻CD27⁺ B-cell subsets in patients with TACI deficiency. (B) Immunoglobulin levels at time of diagnosis in patients with TACI deficiency. Each circle represents a single value from one patient. ● indicates homozygous or compound heterozygous TNFRSF13B mutations; , heterozygous TNFRSF13B mutations other than C104R; ○, C104R heterozygous mutations; and , mean values for each patient group. Testing for significant differences between patient groups was performed with the Student t test.