As examples of protein biomarkers, they proposed the detection of HIgG at ng/mL levels [81] (Figure 5C), anti-hepatitis B antibodies at levels low enough for assuring the efficiency of vaccination (3 mIU/mL) [82] (Figure 5D) and Alzheimer’s disease biomarkers (ApoE and beta amyloid) at diagnostically relevant levels [83]. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.