Genetic Polymorphisms and QF-PCR Performance Evaluation of 20 Autosomal STR Loci on Chromosomes 13, 18, and 21 in Prenatal Diagnosis Among East Chinese Han Population.

OBJECTIVE

To evaluate the system performance of the 20 autosomal short tandem repeats (STR) polymorphic genetic loci in quality control for prenatal diagnosis.

METHODS

A genotyping system consisting of 6 STRs on chromosome 13 (chr13), 6 STRs on chromosome 18 (chr18), 8 STRs on chromosome 21 (chr21), and 10 genetic markers on sex chromosomes were used to analyze the genetic profiles of 2333 unrelated adult females from the Han population in East China. The population allele frequencies of the 20 autosomal STRs were obtained using the genotype dataset of the cohort. The established method in forensic genetic fields was used to calculate allele frequencies of the 20 autosomal STRs, observed heterozygosity ( ), expected heterozygosity (), random match probability (), power of non-parental exclusion in duos ( ), cumulative random match probability (), and cumulative non-parental exclusion rate in duos ( ). The possible influence of STR markers on the detection rates of heterozygotes was assessed by employing the binomial distribution approach for every autosomal chromosome.

RESULTS

The average expected heterozygosity for the STRs on chr13, chr18, and chr21 is 0.8097, 0.7478, and 0.7760, respectively. The for the STRs on the three chromosomes is 4.52E-08, 7.34E-07, and 9.30E-10, respectively. The probability of detecting at least one heterozygosity on each chromosome is 0.999952, 0.999742, and 0.999994, respectively. The of the 20 STRs is 0.999982. And the potential linkage effects among the STRs on the autosomal have a negligible impact on the observed heterozygosity.

CONCLUSION

The 20 autosomal STRs in the 30 plex genotyping system exhibit high polymorphism in the Han population from East China, effective meeting the quality control criteria and providing valuable guidelines in assessing the molecular karyotypes of the chromosomes for prenatal diagnosis.