CD3G and bronchopulmonary dysplasia: The results of qPCR showed that at the level of gene expression, the differential expression trend of four core genes in BPD group and control group was down‐regulation, which indicated that in the course of BPD, the overall expression of TCR complex composed of Cd247, Cd3e, and Cd3g decreased, resulting in the abnormality of biological information transmission in the upstream of T cell receptor signal pathway, which led to the expression of downstream immune related genes, causing immune dysfunction.