MAPT and early-onset autosomal dominant Alzheimer disease: Using a highly sensitive Luminex assay, one study assessed a series of CSF molecules in PD, Alzheimer's disease (AD), multiple system atrophy (MSA) patients, and healthy controls: total tau, phosphorylated tau, amyloid beta peptide 1–42 [Aβ(1–42)], Flt3 ligand, and fractalkine.