We have previously reported that the positive rates of LDH-C4, serum LDHC and exosomal LDHC are 91.55% (130 / 145), 91.66% (22 / 24) and 87.50% (21 / 24) in breast cancer tissues using a microarray analysis [26], which are consistent with the results of this study. The gene discussed is C4A; the disease is breast carcinoma.