Univariate analysis of CVID phenotype patients showed the following to be predictors of deficient humoral response: low IgA values (p=0.043), low CD19+ cells [cell count (p<0.001), percentage (p=0.008) or ≤1% (p<0.011)], switched memory B cells (CD19+CD27+IgD-IgM-) ≤2% (p=0.007), high %CD3+ cells (p=0.008) and low CD4+/CD8+ ratio (p=0.019) [due to low %CD3+CD4+ (p=0.033) as well as high %CD3+CD8+ (p=0.018)]. This evidence concerns the gene CD27 and common variable immunodeficiency.