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International Journal of Alzheimer’s Disease
Volume 2011, Article ID 929102, 5 pages
Research Article

An Intron 7 Polymorphism in APP Affects the Age of Onset of Dementia in Down Syndrome

1Wolfson Centre for Age-Related Diseases, Guy's Campus, King's College London, London SE1 1UL, UK
2Genomics Centre, Franklin-Wilkins Building, King's College London, London SE1 9NH, UK
3Department of Psychiatry, Royal Victoria Infirmary, Newcastle Upon Tyne NE1 4LP, UK
4Learning Disability Medical Directorate, Northgate Hospital, Morpeth, Northumberland NE61 3PB, UK

Received 23 August 2010; Revised 21 October 2010; Accepted 6 December 2010

Academic Editor: Lindsay A. Farrer

Copyright © 2011 Emma L. Jones et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


People with Down syndrome (DS) develop Alzheimer's disease (AD) with an early age of onset. A tetranucleotide repeat, attt5−8, in intron 7 of the amyloid precursor protein has been associated with the age of onset of AD in DS in a preliminary study. The authors examine the impact of this polymorphism in a larger cohort of individuals with DS. Adults with DS were genotyped for attt5−8 and APOE. The results were analysed with respect to the age of onset of dementia. The presence of three copies of the six-repeat allele resulted in onset of dementia seven years earlier than in the presence of other genotypes. Further study is essential to elucidate the mechanism by which this polymorphism functions, with an exciting opportunity to identify novel treatment targets relevant for people with DS and AD.