Alzheimer disease type 1

Alzheimer disease is the most common form of progressive dementia in the elderly. It is a neurodegenerative disorder characterized by the neuropathologic findings of intracellular neurofibrillary tangles (NFT) and extracellular amyloid plaques that accumulate in vulnerable brain regions (Sennvik et al., 2000). Terry and Davies (1980) pointed out that the 'presenile' form, with onset before age 65, is identical to the most common form of late-onset or 'senile' dementia, and suggested the term 'senile dementia of the Alzheimer type' (SDAT). Haines (1991) reviewed the genetics of AD. Selkoe (1996) reviewed the pathophysiology, chromosomal loci, and pathogenetic mechanisms of Alzheimer disease. Theuns and Van Broeckhoven (2000) reviewed the transcriptional regulation of the genes involved in Alzheimer disease. Genetic Heterogeneity of Alzheimer Disease Alzheimer disease is a genetically heterogeneous disorder. See also AD2 (104310), associated with the APOE*4 allele (107741) on chromosome 19; AD3 (607822), caused by mutation in the presenilin-1 gene (PSEN1; 104311) on 14q; and AD4 (606889), caused by mutation in the PSEN2 gene (600759) on 1q31. There is evidence for additional AD loci on other chromosomes; see AD5 (602096) on 12p11; AD6 (605526) on 10q24; AD7 (606187) on 10p13; AD8 (607116) on 20p; AD9 (608907), associated with variation in the ABCA7 gene (605414) on 19p13; AD10 (609636) on 7q36; AD11 (609790) on 9q22; AD12 (611073) on 8p12-q22; AD13 (611152) on 1q21; AD14 (611154) on 1q25; AD15 (604154) on 3q22-q24; AD16 (300756) on Xq21.3; AD17 (615080) on 6p21.2; and AD18 (615590), associated with variation in the ADAM10 gene (602192) on 15q21. Evidence also suggests that mitochondrial DNA polymorphisms may be risk factors in Alzheimer disease (502500). Finally, there have been associations between AD and various polymorphisms in other genes, including alpha-2-macroglobulin (A2M; 103950.0005), low density lipoprotein-related protein-1 (LRP1; 107770), the transferrin gene (TF; 190000), the hemochromatosis gene (HFE; 613609), the NOS3 gene (163729), the vascular endothelial growth factor gene (VEGF; 192240), the ABCA2 gene (600047), and the TNF gene (191160) (see MOLECULAR GENETICS). [from OMIM]