SERPINC1 (Tier 1)
• Protein: Antithrombin-III. UniProt. GeneCards. The allele that increases the risk of ME/CFS is associated with decreasing SERPINC1 gene expression.
• Molecular function: Serine protease inhibitor in plasma that regulates the blood coagulation cascade: AT-III inhibits thrombin and matriptase-3/TMPRSS7, as well as factors IXa, Xa and XIa.
• Cellular function: Extracellular function.
• Link to disease: Mutations in SERPINC1 cause antithrombin-III deficiency, which is a strong risk factor for thrombosis. A reduction in the serum level of this protein is associated with severe cases of COVID-19. Mutated in cerebral venous sinus thrombosis (CVST).
• Potential relevance to ME/CFS: Previously proposed role of ischaemia–reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long Covid, and ME/CFS (23). Reduction in SERPINC1 levels expected to increase risk of blood clots. However, the eQTL is only found in brain tissue, where it is only expressed at a low level.