There was no statistically significant difference between the serum IgA concentrations in all children with IgAV (983.8 ± 593.7 μg/mL) compared to HC (720.5 ± 337.3 μg/mL; p = 0.336) or between groups when patients were stratified according to the presence of nephritis (IgAVN—1113.0 ± 746.6 μg/mL; IgAVwoN—872.5 ± 457.4 μg/mL; HC—720.5 ± 337.3; p = 0.544). The gene discussed is CD79A; the disease is nephritis.