Expression levels of differentially expressed genes (DEGs) in validation cohort by quantitative reverse transcription–polymerase chain reaction (qRT–PCR) in 30 paired samples. The mRNA expression levels of glutathione S‐transferase mu 1 (GSTM1), T transmembrane protein 176 (TMEM176)A, TMEM176B, N‐ethylmaleimide‐sensitive factor pseudogene 1 (NSF‐P1), myosin light‐chain 4 (MYL4), solute carrier family 4 member (SLC4A)1, SLC4A10 and ubiquitously transcribed tetratricopeptide repeat containing, Y‐linked (UTY) are presented, respectively. Data are presented as the relative fold change in expression. Asterisk indicates a significant difference when compares with controls. *P < 0·05; **P < 0·01; ***P < 0·001. DEGs: differentially expressed genes.