Apolipoprotein E and presenilin-1 allelic variation and Alzheimer's disease in India.

As part of a larger epidemiological survey to study the prevalence of dementia in a suburb of Mumbai, Western India, we identified 78 cases with a Clinical Dementia Rating (CDR) > or = 1.0. Of these, 49 Alzheimer's disease (AD) cases were analyzed for risk association with APOE E*4 allele at apolipoprotein E gene (APOE) and presenilin-1 (PS-1) intron-8 polymorphism and were compared with 100 age- and sex-matched nondemented controls. Genotype analysis confirmed the association of APOE E*4 allele with AD as has been reported by various studies. We report a low frequency of APOE E*4 allele, consistent with a low prevalence of AD in this study. Comparisons with other similar studies on APOE from India suggest common risk factors for AD in the Indian population, which is diverse in its ethnic and racial characteristics. The frequency for allele 1 at PS-1 intron-8 polymorphism is the highest among all studies reported. This first report of PS-1 intron-8 polymorphism and AD from India demonstrates no significant association.