Previously we identified “Parkinson’s disease”, “Huntington’s disease”, “Prion disease”, “Alzheimer’s disease”, “Retrograde endocannabinoid signalling”, “Oxidative phosphorylation”, “Oestrogen signalling pathway”, “Non-alcoholic fatty liver disease”, “SLE”, “Complement and coagulation cascades”, “Metabolic pathways” and “Apelin signalling” as citrullinome-associated KEGG pathways in PD plasma and/or plasma-EVs [4]. Here, APLN is linked to systemic lupus erythematosus.