α₂-Macroglobulin gene polymorphisms show racial diversity and are not associated with Alzheimer's disease

Two genetic markers of the plasma protein α₂-macroglobulin, a 5 bp deletion/insertion at the 5' splice site of exon 18 (A2M1) and the GTC/ATC (Val1000I1e) in exon 24 (A2M2), may have roles in the development of Alzheimer's disease (AD). Genotyping and linkage analysis of these markers in 426 Japanese sporadic AD patients, 85 autopsy-confirmed Caucasian AD cases, and, as controls, 382 Japanese and 65 Caucasians who were cognitively normal and 140 Japanese Parkinson's disease patients showed racial diversity in the frequencies and relationship of the two markers. Comparison of genotype and allele frequencies, stratification of the samples by the presence of the apolipoprotein E ε4 allele, and logistic regression analysis revealed no association of these markers with AD in either racial group. (C) 2000 Lippincott Williams and Wilkins.