Background

Down syndrome (DS) patients unanimously develop pathologies of Alzheimer’s disease (AD) in their 30s or 40s. Since DS is caused by the existence of an extra copy of chromosome 21 in cells, an over-dosage of genes on chromosome 21 may play a role in the pathogenesis of DS and perhaps AD as well. This idea has been well-supported in the case of the APP gene over-dosage which leads to overproduction of the neurotoxic b-amyloid (Ab) peptides, the prime culprit in AD pathogenesis. However, the invol-vement of other genes on chromosome 21 in AD has barely been studied. Sorting nexin 27 (SNX27), a brain-enriched PDZ domain protein, regulates endocytic sorting and trafficking. Methods and results Recently, we showed [1] that Snx27-/- mice have sever