Molecular abnormalities of the brain in Down syndrome: relevance to Alzheimer's neurodegeneration

J Neural Transm Suppl. 1999;57:1-19. doi: 10.1007/978-3-7091-6380-1_1.


Down syndrome is caused by over-expression of genes located within a segment of chromosome 21, termed the Down locus. Down syndrome is associated with developmental abnormalities of the central nervous system that result in mental retardation and age-dependent Alzheimer-type neurodegeneration. Some of the neurodegenerative lesions, including A beta amyloid deposition, apoptotic cell death, and aberrant dendritic arborization, are in part due to constitutively increased expression of genes that encode the amyloid precursor protein, superoxide dismutase I, and S100-beta, and located within the Down locus. However, neurodegeneration in Down syndrome is also associated with aberrant expression of genes that are not linked to the Down locus, including the growth associated protein, GAP-43, nitric oxide synthase 3, neuronal thread protein, and pro-apoptosis genes such as p53, Bax, and interleukin-1 beta-converting enzyme. Increased expression of these non-Down locus genes correlates with proliferation of dystrophic neurites and apoptotic cell death, two important correlates of cognitive impairment in Alzheimer's disease. This article reviews the functional importance of abnormal gene expression in relation to Alzheimer-type neurodegeneration in brains of individuals with Down syndrome.

Publication types

  • Review

MeSH terms

  • Alzheimer Disease / genetics*
  • Alzheimer Disease / metabolism
  • Alzheimer Disease / pathology
  • Amyloid beta-Protein Precursor / genetics
  • Brain / metabolism
  • Brain / pathology*
  • Down Syndrome / genetics*
  • Down Syndrome / metabolism
  • Down Syndrome / pathology
  • Humans
  • Nerve Degeneration
  • S100 Proteins / genetics
  • Superoxide Dismutase / genetics


  • Amyloid beta-Protein Precursor
  • S100 Proteins
  • S100A1 protein
  • Superoxide Dismutase