Cerebrospinal fluid (CSF) biomarkers consisting of Aβ1–42, total-tau (t-tau), and phosphorylated-tau (p-tau) have been shown to reflect the disease course and may even indicate preclinical disease.8–11 Typically, decreased CSF Aβ1–42 and increased t-tau and p-tau reflect AD plaque accumulation and neurodegeneration, respectively. The gene discussed is MAPT; the disease is Alzheimer disease.