Rehman et al. [131] reviewed 75 proteins present in CSF, suggesting that ApoD, together with 5 other proteins (apolipoprotein E, α1-microglobulin, complement component 3, interleukin 16, insulin-like growth factor binding protein 2), may serve as an effective biomarker to differentiate patients with mild cognitive impairment from AD and cognitively normal individuals. The gene discussed is APOE; the disease is Alzheimer disease.