A Study On The Mutations In Exon 5～9 Of PS-1 Gene

As a common disease in elderly population, senile dementia has been the 4th fatal factor in west developed countries. Alzheimer's disease is the main form of senile dementia. It has been reported that there are at least 4 genes connecting with AD. PS-1 is the most important one, and it accounts for more than half of early-onset and familial AD. In order to find out the types and frequency of the mutations in PS-1 gene and to evaluate its risk in Chinese population, we screen the mutations in the 5 to 9 exons of PS-1 gene among 120 health Chinese by PCR-SSCP. No mutation is found. It suggests that the mutation frequency of PS-1 gene is quite low, and it may not be the main risk for AD in Chinese population. But we find a polymorphism in the intron 9 in this study. There are two different alleles at nucleotide 16 in this intron: T and G, which form into three genotypes. In Chinese, the most common genotype is T/G with frequency 65.8%, the other one is T/T with frequency 34.2%, and no G/G was found in our study. The frequency of allele T is 67.1% while that of G is 32.9% at 16 nucleotide. The frequencies of genotype and allele are similar to relative articles. We still can not draw the conclusion that the intronic polymorphism in PS-1 is associated with AD by comparing with relative articles and studies. More researches are need to be performed.