Among AKI episodes with an abnormal SPEP, 75 % were IgG, 12 % were IgA, 8 % were IgM, and in 5 % only faint free light chains were identified; overall, 63 % consisted of monoclonal kappa and 37 % consisted of monoclonal lambda; the median M-spike concentration was 0.9 (IQR, 0.5-2.4 g/dl). The gene discussed is CD40LG; the disease is acute kidney injury.