RESUMO
Objective To investigate the genetic polymorphisms of 3 short tandem repeat (STR) loci D18S53, D18S59 and D18S488 on chromosome 18 in fetus of Tianjin Han population, and to provide basic data in the use of 3 STR lo-ci in the prenatal diagnosis of Edward syndrome (ES). Methods A total of 64 villus samples and 374 amniotic fluid sam-ples were collected from gravida in Tianjin Han population. QF-PCR and ABI PRISM 377 sequence were used in this study. The frequencies of the genotypes were tested with H-W equilibrium. Genetic analysis was performed to conclude some data of population genetics such as the frequency of the alleles, the heterozygosity of observation (Ho), the polymorphism informa-tion content (PIC), the probability of discrimination power (DP), and the probability of exclusion (PE). Results The 15, 13 and 15 alleles of D18S53, D18S59 and D18S488 were observed respectively. The frequencies of the genotypes were in good agreement with H-W equilibrium. The Ho of 3 STR loci were 0.797, 0.847 and 0.792. The PIC was 0.81, 0.75 and 0.73. The DP was 0.944, 0.901 and 0.881. The PE was 0.593, 0.689 and 0.585. Conclusion D18S53, D18S59 and D18S488 STR lo-ci were the favorable genetic markers of chromosome 18, which can be used in prenatal genetic diagnosis of ES.
