Table 1.
Reported expression of ACE2 protein in human tissues and the corresponding COVID-19 symptoms
| Tissue name | ACE2 protein expression | ACE2 protein expression levels | Related COVID-19 symptoms |
|---|---|---|---|
| Duodenum | ✓ | High | GI disturbance |
| Gallbladder | ✓ | High | NA |
| Heart | ✓ | High | Heart injury |
| Kidney | ✓ | High | Kidney injury |
| Small intestines | ✓ | High | Diarrhea and other GI disturbance |
| Testis | ✓ | High | NA |
| Adrenal gland | ✓ | Medium | NA |
| Colon | ✓ | Medium | Diarrhea |
| Rectum | ✓ | Medium | NA |
| Brain | ✓ (validated via enzymatic activity assays) | Low | Loss of taste or smell, respiratory failure, and other neurological symptoms |
| Liver | ✓ | Low | Increased levels of liver enzymes (ALT, AST) |
| Lung | ✓ | Low | Pneumonia and respiratory symptoms |
| Oral mucosa | ✓ | Low | NA |
| Seminal vesicle | Only in glandular cells | Low | NA |
| Skin | ✓ | Low | A rash on skin, or discoloration of fingers or toes |
| Spleen | Only in vascular and red pulp sinus endothelium | Low | NA |
| Eye | NA | NA | Conjunctivitis |
| Adipose tissue | × | ||
| Common blood cells | × | Abnormal blood clotting | |
| Endometrium | × | ||
| Esophagus | × | ||
| Nasopharynx | × | ||
| Stomach | × |
The data of ACE2 protein expression were obtained via published reports (Hamming et al. 2004; Kehoe et al. 2016; Xu et al. 2017; Hikmet et al. 2020) and version 19 of the Human Protein Atlas (https://www.proteinatlas.org). The data of related COVID-19 symptoms were obtained via the website of Centers for Disease Control and Prevention (CDC)
“✓”: yes; “×”: no; NA: data are currently not available