Characteristics Study Of STR Typing In Patients With Trisomy 21 And Klinefelter’s Syndrome

Objective:To identify the characteristics of different triallelic pattern of D21S11and Penta D loci in autosomal short tandem repeat（STR）typing of patients with down syndrome（DS）,and to explore the feasibility of rapid detection of DS with GoldenEye^TM 20A kit application.Methods:Source for chromosome karyotype analysis in peripheral blood results for the DS patients and normal individuals in paternity test casas as the research object.DNA of peripheral blood nucleated cells was extracted with Qiagen blood mini kit.Multiple fluorescent polymerase chain reaction（PCR）was performed using GoldenEye^TM 20A kit.The 3500-DX genetic analyzer was used for capillary electrophoresis.STR typing results of 19 autosomal genes were determined after GeneMapper ID-X 1.4 software processing.Through the peak area,peak height and ratio,the characteristics of STR typing map were analyzed.Results:Karyotype analysis of G-banding chromosome confirmed that chromosome 21 in 94 DS patients was three chromatids.Contrary to 100 normal persons STR typing without tri-allelic pattern,Among the D21S11 loci of 94 DS patients,there were 45 cases of tri-peak in triallelic pattern,38 cases of bimodal-peak and 11 cases of unimodal genes,respectively.The detection rate of DS only through D21S11 loci was 47.87%.Among the Penta D loci of them,there were34 cases of tri-peak in triallelic pattern,49 cases of bimodal-peak and 11 cases of unimodal genes,respectively.The detection rate of DS through Penta D was 36.17%.Combined with the analysis of the two loci,33 cases with tri-peak,bimodal-peak and unimodal-peak were found to have D21S11 and Penta D loci in tri-allelic patterns.There were 59 cases in which one of the D21S11 or Penta D was tri-peak or bimodal-peak allelic pattern,and the other locus was a bimodal-peak or unimodal-peak.Two cases did not conform to the bimodal-peak.The detection rate of DS combined with two loci was 97.87%.Conclusion:Combined with the D21S11 and Penta D loci in the GoldenEye^TM20A kit,DS patients have 6 different tri-allelic gene expression forms,which greatly improves the positive detection rate and has a good application prospect for rapid detection of DS.Objective:Golden Eye TM 20 A kit and short tandem repeat（STR）typing were used to investigate the potential value of AMEL loci STR mapping feature on forensic identification and rapid clinical detection in special patients with Klinefelter’s syndrome（KS）.Methods: Source of sample was KS patients as the research object after diagnosis of chromosome karyotype analysis.The DNA was extracted in peripheral venous blood by using Qiagen blood mini kit.Polymerase chain reaction（PCR）was performed by using Golden EyeTM 20 A kit.Capillary electrophoresis was performed in 3500-DX genetic analyzer.STR typing results of KS patients were obtained after data analysis from Gene Mapper ID-X 1.4 software processing and determined the AMEL loci mapping characteristics.Results: Karyotype analysis showed that normal males were 46,XY,while among 32 KS patients,31 were homozygous type（47,XXY）,and 1 was mutant type（47,XXY,15cenh+）.No obvious abnormalities were found in the 19 autosomal STR genotypes.The peak height and peak area ratio of AMEL locus on the sex chromosome of 28 KS patients was > 1.65.It was judged that the X allele ratio of AMEL on the sex chromosome increased,that is,the number of X chromosomes increased.The peak height ratio of AMEL locus in 4 case of KS patients ranged from 0.82 to 1.64,and the peak area of AMEL locus in 1 patient was >1.65.According to the X/Y peak area ratio or the combined X/Y peak height ratio,the detection rates of KS detected by Golden Eye TM 20 A kit were 93.55% and 90.32%,respectively.The X/Y peak area ratio and peak height ratio of KS patients were significantly higher than that of normal males.Conclusion: The Golden Eye TM 20 A kit was used for STR typing test,and the X and Y characteristic peaks were showed in the AMEL locus on sex chromosome of above 90% KS patients.It may have a good application prospect in the forensic identification of special KS disease population and the rapid clinical screening and diagnosis.