CSF amyloid‐β1‐42 (Aβ1‐42), total tau protein (t‐tau), and phosphorylated tau at threonine 181 (p‐tau) mirror the main neuropathological hallmarks of AD and are well established to aid in the diagnosis of AD.7 AD‐like pathology, that is, neurofibrillary tangles and amyloid plaques, is also found in almost half of patients with DLB.8, 9 Therefore, CSF AD biomarkers have an added value to distinguish DLB from healthy subjects and to some extent from PD. The gene discussed is MAPT; the disease is Alzheimer disease.