[Use of unlinked genetic markers to detect population stratification: a case-control multicenter study]

To evaluate whether population stratification exists in microsatellite polymorphic sites.

Eight microsatellite markers not related to stroke, D11S1361, D19S927, D7S483, D14S990, D15S993, D1S2622, D1S2876 and D3S3560 located in different chromosomes were selected based on the GenBank database (http://www.gdb.org/). PCR assay was used to detect the alleles of these microsatellite in 294 patients of cerebral apoplexy, aged 58, and 325 sex, age and geographically-match controls in 7 cities in China. The PCR products were subjected to electrophoresis on the ABI 377 DNA sequencer and analyzed with Genescana and Genotypera software. The frequencies of these markers in these stroke patients and controls were compared by c2 test. Total 294 patients with stroke and 325 age, sex, and geographically matched controls were randomly selected from 973 case-control population. Eight loci including D11S1361, D19S927, D7S483, D14S990, D15S993, D1S2622, D1S2876 and D3S3560 were detected by fluorescence-based genotyping approach.

Except for the alleles of D11S1361, the size, frequency, heterozygosity, and polymorphism information in the alleles of the other 7 microsatellite sites were in the range of 0.63 - 0.81 and their distribution varies in different races and populations. between Chinese and Caucasians. There were no differences in the frequencies of main alleles between the case group and control group (all P > or = 0.05).

The selected seven markers are highly polymorphic and variable between human populations, and the genomic control data indicate that there is no unequal genetic admixture and stratification in the case-control cohort.