Meanwhile, comparing stages CAR and IAR, twenty-five KOs were significantly down-regulated or up-regulated, including glycolysis/gluconeogenesis, carbon fixation in photosynthetic organisms, alzheimer’s disease, starch and sucrose metabolism, cysteine and methionine metabolism, arginine and proline metabolism, MAPK signaling pathway, ABC transporters, valine, leucine and isoleucine degradation, antigen processing and presentation, nitrogen metabolism, tryptophan metabolism and selenoamino acid metabolism (Additional file 11). The gene discussed is ABCG2; the disease is Alzheimer disease.