Presentation of the values of r-Pearson correlation coefficients from the analysis of the dependence of specific IgA class antibody titres on the age of healthy children or PID patients (weak correlation r from -0.5 to 0.0 and 0.0 to 0.5, strong correlation r from -1.0 to -0.5 and 0.5 to 1.0). The gene discussed is CD79A; the disease is pelvic inflammatory disease.