Twelve genes, CPT1A, GLYATL1, SDHA, SDHB, SDHC, SDHD, SIRT1, SIRT3, SIRT5, SUCLA2, SUCLG1 and SUCLG2, demonstrated lower expression in tumour than adjacent tissues (Figure 4 and Figure 5).Three clusters were identified using the NMF algorithm (Figure 6A), and parameter K = 3 showed the optimal number. This evidence concerns the gene SDHD and neoplasm.