In the validation dataset (GSE248612), KEGG pathway analysis for upregulated genes revealed three prominent pathways: salivary secretion (involving CST2 and CST1 genes, p-value 0.0009, odds ratio 54.67), Staphylococcus aureus infection (KRT17 and KRT16, p-value 0.0010, odds ratio 53.49), and estrogen signaling pathway (KRT17 and KRT16, p-value 0.0020, odds ratio 36.77). The gene discussed is CST2; the disease is staphylococcus aureus infection.