Alzheimer Disease: Collins JS

Perry RT, Collins JS, Wiener H, Acton R, Go RC. · Department of Epidemiology and International Health, University of Alabama at Birmingham, 35294, USA. · Neurobiol Aging. · Pubmed #11754994 No free full text.

Abstract: Tumor necrosis factor (TNF) is an important proinflammatory cytokine that is upregulated in Alzheimer disease (AD) patients and involved with AD genes. Several TNF promoter polymorphisms that increase expression are associated with inflammatory and infectious diseases. We previously reported results that detected a AD associated region near the TNF gene. Using family-based association tests we also reported an association between AD and a TNF haplotype in sibling-pair families, and a significant increase in the mean age of onset for a group of African-American AD patients carrying this same haplotype. Previous reports have shown that that the chromosome 1p and chromosome 12p regions are linked to late-onset AD. These two regions harbor TNF receptors (TNFR) 2 and 1, respectively, and binding to them mediates biological effects of TNF. We found a significant asssociation of a TNFR2 exon 6 polymorphism with late-onset AD in families with no individuals possessing the APOE E4E4 genotype under a dominant model. We found no significant association of three polymorphisms in the TNFR1 gene to AD. These results provide further evidence for the involvement of TNF in the pathogenesis of AD.

Blacker D, Bertram L, Saunders AJ, Moscarillo TJ, Albert MS, Wiener H, Perry RT, Collins JS, Harrell LE, Go RC, Mahoney A, Beaty T, Fallin MD, Avramopoulos D, Chase GA, Folstein MF, McInnis MG, Bassett SS, Doheny KJ, Pugh EW, Tanzi RE, Anonymous00039. · Massachusetts General Hospital, Charlestown, MA, USA. · Hum Mol Genet. · Pubmed #12490529 links to  free full text

Abstract: Alzheimer's disease (AD) is a devastating neurodegenerative disorder of late life with complex inheritance. Mutations in three known genes lead to the rare early-onset autosomal dominant form of AD, while a common polymorphism (epsilon 4) in the gene encoding apolipoprotein E (APOE ) is a risk factor for more typical late-onset (>60 years) AD. A recent study concluded that there are up to four additional genes with an equal or greater contribution to the disease. We performed a 9 cM genome screen of 437 families with AD, the full National Institute of Mental Health (NIMH) sample, which has been carefully ascertained, evaluated and followed by our group over the last decade. Performing standard parametric and non-parametric linkage analyses, we observed a 'highly significant' linkage peak by Lander and Kruglyak criteria on chromosome 19q13, which probably represents APOE. Twelve additional locations-on 1q23, 3p26, 4q32, 5p14, 6p21, 6q27, 9q22, 10q24, 11q25, 14q22, 15q26 and 21q22-met criteria for 'suggestive' linkage [i.e. two-point lod score (TLS) >/=1.9 and/or multipoint lod score (MLS) >/=2.2] in at least one of our analyses. Although some of these will surely prove to be false positives, these linkage signals should provide a valuable framework for future studies aimed at identifying additional susceptibility genes for late-onset AD.

Perry RT, Collins JS, Harrell LE, Acton RT, Go RC. · Department of Epidemiology and International Health, University of Alabama at Birmingham, 35294, USA. · Am J Med Genet. · Pubmed #11378846 No free full text.

Abstract: Alzheimer disease (AD) is an emotionally devastating and exceptionally costly disease. Apolipoprotein E (APOE) is a major risk factor gene for AD regardless of age of onset or family history. However, this association may not be as strong or consistent in ethnic groups such as African Americans, raising the possibility of other modifier gene(s). In a group of African American AD patients, a significantly increased risk of AD was associated with two E4 alleles (OR = 5.6; 95% CI = 1.5-21.0) or one E4 allele (OR = 2.5; 95% CI = 1.3-5.0) when compared to E3/E3 genotype, and there was a significant lowering of age of onset for affecteds with E4/E4 genotype as compared to one E2 allele (P = 0.02) or all others (P = 0.03). We also found a significant increase in age of onset with the -308 #2 (A) allele of TNF when compared to AD cases with no #2 allele. A significant increase in age was also demonstrated with the #2 allele (99 base pairs) of the microsatellite TNFa, located approximately 10.5 kb upstream of TNF. When these two alleles were combined with the TNF -238G (#1) allele to give a haplotype, the significant increase in age was still demonstrated. Polymorphisms in the APOE promoter and six other candidate genes did not appear to demonstrate any significant association with our African American AD patients. Our results confirm the established association of APOE4 to AD observed in several ethnic groups, including African Americans. In addition, TNF appears to have some modifying effect in AD, primarily on age of onset, or it could be in linkage disequilibrium with a modifier locus nearby.

Collins JS, Perry RT, Watson B, Harrell LE, Acton RT, Blacker D, Albert MS, Tanzi RE, Bassett SS, McInnis MG, Campbell RD, Go RC. · Department of Epidemiology and International Health, University of Alabama at Birmingham, Birmingham, Alabama 35294-0022, USA. · Am J Med Genet. · Pubmed #11121190 No free full text.

Abstract: Tumor necrosis factor (TNF), a proinflammatory cytokine, may be involved in the pathogenesis of Alzheimer disease (AD) based on observations that senile plaques have been found to upregulate proinflammatory cytokines. Additionally, nonsteroidal anti-inflammatory drugs have been found to delay and prevent the onset of AD. A collaborative genome-wide scan for AD genes in 266 late-onset families implicated a 20 centimorgan region at chromosome 6p21.3 that includes the TNF gene. Three TNF polymorphisms, a -308 TNF promoter polymorphism, whose TNF2 allele is associated with autoimmune inflammatory diseases and strong transcriptional activity, the -238 TNF promoter polymorphism, and the microsatellite TNFa, whose 2 allele is associated with a high TNF secretion, were typed in 145 families consisting of 562 affected and unaffected siblings. These polymorphisms formed a haplotype, 2-1-2, respectively, that was significantly associated with AD (P = 0.005) using the sibling disequilibrium test. Singly, the TNFa2 allele was also significantly associated (P = 0.04) with AD in these 145 families. This TNF association with AD lends further support for an inflammatory process in the pathogenesis of AD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:823-830, 2000.