Link between DYRK1A overexpression and several-fold enhancement of neurofibrillary degeneration with 3-repeat tau protein in Down syndrome.

Triplication of chromosome 21 in Down syndrome (DS) results in overexpression of the minibrain kinase/dual-specificity tyrosine phosphorylated and regulated kinase 1A gene (DYRK1A). DYRK1A phosphorylates cytoplasmic tau protein and appears in intraneuronal neurofibrillary tangles (NFTs). We have previously shown significantly more DYRK1A-positive NFTs in DS brains than in sporadic Alzheimer disease (AD) brains.