A plasma protein signature with five proteins could identify mild AD patients: apolipoprotein A‐1, α‐2‐HS‐glycoprotein, and afamin were downregulated, whereas apolipoprotein A4 (ApoA4) and fibrinogen gamma chain were upregulated in a small sample size of mild AD patients.75 This evidence concerns the gene APOA1 and Alzheimer disease.