TTC21A and prion disease: KEGG pathway enrichment suggested that TTC21A co-expression genes were negatively associated with glycosphingolipid biosynthesis, prion diseases, terpenoid backbone biosynthesis, biosynthesis of unsaturated fatty acids, adherens junction, ferroptosis, protein processing in endoplasmic reticulum, oxidative phosphorylation, peroxisome, carbon metabolism, valine, leucine and isoleucine degradation, and citrate cycle (TCA cycle) (Figure 6E).