Table 1.

Summary of differentially expressed genes (DEGs) by class. Gene class 1 and 2 correspond to DEGs with low expression compared to other genes in both young and old age groups. Gene class 3 and 4 correspond to DEGs with low expression compared to other genes in one group and a high expression in another group. Gene class 5 and 6 correspond to DEGs with high expression compared to other genes in both young and old age groups.

Gene Class	Number of Genes Included	Expression in the Young Age Group Compared to Average	Expression in the Old Age Group Compared to Average	Down- or Upregulated during Aging
1	328	Lower	Lower	Downregulated
2	408	Lower	Lower	Upregulated
3	178	Higher	Lower	Downregulated
4	154	Lower	Higher	Upregulated
5	63	Higher	Higher	Downregulated
6	94	Higher	Higher	Upregulated