一例胎儿微小额外标记染色体46,X,+mar羊水样本的遗传学检测分析

Genetic detection and analysis of a fetal small supernumerary marker chromosome 46,X,+mar amniotic fluid sample

目的通过染色体非整倍体分析和Y染色体STR分析,对一例染色体核型为46,X,+mar的羊水标本进行遗传学分析。方法采用多重荧光定量聚合酶链反应(QF-PCR)进行常见染色体非整倍体检测;利用AGCU Y-STRs多重荧光复合扩增分析系统检测DYS391等22个STR位点。结果羊水标本在13、18、21号染色体基因座上,为峰高1∶1的双峰或两倍峰高的单峰,AMELY、XY3基因座的STRs峰高两倍于X染色体基因座峰高。AGCU YSTR多重荧光复合扩增分析系统检测结果显示,其父亲外周血在22个Y-STR位点上均检测到单峰。胎儿羊水标本在DYS456、DYS458、DYS393、DYS19、DYS522五个基因座上检测到单峰,其余17个基因座未检测到扩增产物。在以上五个基因座上,其基因型均与父亲一致。结论羊水标本性别染色体Y和X比例为2∶1,Y染色体有部分缺失,Y染色体上5个基因座的基因型来源于父亲。

Objective Through chromosome aneuploidy analysis and analysis of a short tandem repeat on the Y-chromosome(Y-STR),a genetic analysis of an amniotic fluid specimen with chromosome 46,X,+mar was performed.Methods Quantitative fluorescence polymerase chain reaction(QF-PCR)was used to detect common chromosomal aneuploidies;the AGCU Y-STRs quantitative fluorescent multiplexing PCR amplification analysis system was used to detect 22 STR loci such as DYS391.Results The amniotic fluid specimen was detected double peaks with a peak height of 1∶1 or single peaks with a double peak height on the loci of chromosome 13,18,and 21.The peak height of STRs at the AMELY and XY3 loci was twice as high as that of the X-chromosome loci.The detection results of AGCU Y-STR quantitative fluorescent multiplexing PCR amplification analysis system showed that the peripheral blood of his father was detected a single peak at 22 Y-STR loci.Fetal amniotic fluid specimen was captured single peaks at five loci including DYS456,DYS458,DYS393,DYS19,and DYS522,and no amplified products were detected at the remaining 17 loci.At the above five loci,their genotypes were consistent with those of the father.Conclusion The ratio of sex chromosomes Y to X in amniotic fluid specimens is 2∶1.The Y-chromosome has partial deletions.The genotypes of five loci on the Y-chromosome are derived from the father.