Abbreviations: 95% CI, 95% confidence interval; AD, Alzheimer’s disease; aMCI, amnestic mild cognitive impairment; AUC, area under the curve; GFAP, glial fibrillary acidic protein; NfL, neurofilament light; NA, not available; PDD, Parkinson’s disease dementia; p-tau217, phosphorylated tau; SEN, sensitivity; SPE, specificity; SV2A, synaptic vesicle glycoprotein 2 A; VaD, vascular dementia; vs., versus. The gene discussed is XK; the disease is early-onset autosomal dominant Alzheimer disease.