Table 2. Genes analyzed in at least three research articles and included in the systematic review.
| Gene | Gene Function | Total Number of Articles that Analyzed the Gene | Number of Articles that Found Significant Increase in Cases vs Controls | Number of Articles that Found Significant Decrease in Cases vs Controls | Number of Articles that Found No Significant Difference in Cases vs Controls |
|---|---|---|---|---|---|
| FBXO32 (ATROGIN1) | Protein degradation | 12 | 4 [18, 24, 26, 27] | 1 [17] | 7 [5, 6, 12–16] |
| TRIM63 (MURF1) | Protein degradation | 12 | 2 [18, 24] | 1 [17] | 9 [5, 6, 12–16, 26, 27] |
| UBIQUITIN | Protein degradation | 5 | 4 [19, 22, 28, 29] | 0 | 1 [30] |
| BECN1 | Autophagy | 3 | 1a [6] | 0 | 2 [27, 31] |
| GABARAPL1 | Autophagy | 3 | 2b [5, 15] | 0 | 1 [12] |
| MAP1LC3B2 (LC3B) | Autophagy | 3 | 1c [31] | 0 | 2 [6, 27] |
| SQSTM1 (p62) | Autophagy | 3 | 1 [15] | 0 | 2 [6, 31] |
| BNIP3 | Apoptosis | 4 | 1d [16] | 0 | 3e [5, 12, 31] |
| FOXO3 | Apoptosis | 4 | 1 [32] | 0 | 3f [6, 15, 18] |
| MSTN | Muscle differentiation/ growth (Negative regulator) |
7 | 3 [6, 25, 27] | 2g [14, 33] | 2 [13, 23] |
| MYOD1 | Muscle differentiation/ growth |
5 | 2 [6, 34] | 0 | 3 [23, 27, 33] |
| MYOG | Muscle differentiation/growth | 4 | 1 [6] | 1 [35] | 2 [27, 33] |
| MYF5 | Muscle differentiation/growth | 3 | 0 | 0 | 3 [6, 27, 34] |
| FOXO1 | Insulin/IGF1 pathway | 4 | 4h,i [6, 15, 18, 32] | 0 | 0 |
| IGF1 | Insulin/IGF1 pathway | 4 | 1 [32] | 2j [14, 33] | 1 [23] |
| TNF | Inflammation | 5 | 2 [25, 35] | 0 | 3 [13, 23, 32] |
| IL-6 | Inflammation | 3 | 2 [13, 25] | 0 | 1 [32] |
| TFAM | Mitochondrial transcription regulation | 3 | 0 | 0 | 3j [20, 21, 36] |
Gene function was assigned according to www.genecards.org Some genes, particularly FOXO1 and FOXO3, can be classified as part of multiple pathways.
a Kneppers 2017 found significant increase in all chronic obstructive pulmonary disease (COPD) cases vs controls but no significant differences between COPD sarcopenia and COPD no sarcopenia
b Stephens 2015 found significant increase in all cancer cases vs controls but no significant differences in cancer cachexia vs cancer no cachexia
c Aversa 2016 found a significant increase in cancer cachexia cases vs controls
d Op den Kamp 2013 found significant increase in NSCLC cachexia vs controls; increased in NSCLC cachexia vs precachexia cases
e Stephens 2015 found trend towards increase in all cancer cases vs controls (p = 0.058)
f Doucet 2017 found no significant differences in COPD low muscle mass vs COPD preserved muscle mass
g Puig-Villanova 2015 found significant decrease in all COPD cases vs healthy controls; decreased in COPD with muscle weakness vs healthy controls; NS differences between COPD no muscle weakness and healthy controls
h Doucet 2007 found significant increase in all COPD cases vs controls but no significant differences between COPD low muscle mass and COPD preserved muscle mass
i Kneppers 2017 found significant increase in COPD sarcopenic vs healthy controls
j Remels 2007 found no significant difference between all COPD cases and controls but significantly lower in COPD cachectic vs COPD non-cachectic