It should be noted that a weak association between clinical diagnosis and propionate levels emerged when the statistical model was corrected for APOE ε4 carrier status (i.e., CI-AD > CI-NAD), the main AD genetic risk factor known to impact the GM profile.10,11 Although APOE ε4 did not clearly affect the other SCFAs (Supplemental Table 1), future research investigating the impact of the APOE genotype on the association between SCFAs and brain pathology in the context of AD is necessary. The gene discussed is APOE; the disease is Alzheimer disease.