ABSTRACT
STR typing for several loci has been regarded as a standard method for individual identification. The result is rather simple and easy to be interpreted. For each loci one allele for homozygote and two different alleles for heterozygote are expressed as simple peaks. Many peaks more than two suggest unusual situations such as contamination. We experienced two cases of three alleles in two separate samples. Among 15 STR loci typed using AmpFlSTR.. Identifiler.. Kit(Applied Biosystems, Foster City, CA) and Powerplex..16 system (Promega, Madison, WI), three alleles were noted in D8S1179 locus in one sample, in D21S11 locus in another sample. We sequenced all the three amplified alleles through cloning to reveal the structure, and amplified nearby regions to check the extent of three alleles. We present the results here together with review on many alleles in one sample.
ABSTRACT
Objective To set a rapid,simple gene diagnosis method for Down syndrome.Methods Three short tandem repeats(D21S11,D21S1270,D21S1437)loci in or near Down syndrome critical region(DSCR) were analyzed and detected by polymerase chain reaction and DNA quantitative analysis in 11 core ancestry.Results There were four types by DNA quantitative analysis to different individuals at a short tandem repeats(STR) locus.In type one,a homozygote of one allelic gene was detected.In type two,a normal heterozygote of two allelic genes was found,the content or two DNA electrophoresis bands was approximately 1∶1.In type three,a Down syndrome patient of two allelic genes was discovered.The quantity of two electrophoresis bands was nearly 2∶1.In type four,the patient showed three DNA electrophoresis bands which the content was approximately 1∶1∶1.Conclusion A rapid gene diagnosis and prenatal diagnosis method for Down syndrome can be used for quantitative analysis of STR polymorphism loci.