Markers of neurodegeneration showed consistent elevation in AD, including neurofilament light chain (NFL) (18.81 ± 9.06 pg/mL versus 11.85 ± 6.71 pg/mL; P = 0.0034) and APOE4 (47.54 ± 29.55 ng/mL versus 25.77 ± 10.42 ng/mL; P = 0.0011), while total APOE levels were not significant (P = ns), underscoring the relevance of isoform-specific profiling. The gene discussed is APOE; the disease is Alzheimer disease.