摘要
目的探讨PCR短串联重复（PCR—shorttandemrepeat，PCR—STR）法快速产前筛查唐氏综合征（Downsyndrome，DS）的应用价值及7个STR位点多态性分布特点。方法选择21号染色体核心区域（21q22．1—21q22．2）及其附近的7个STR位点（D21S11、D21S1411、D21S1412、D21S1413、D21S1414、D21S1432、D21S2039），应用PCR—STR扩增对978例高危孕妇羊水样本和82例疑似DS患者外周血样本进行基因诊断筛查检测，并与细胞培养染色体核型分析结果比较。结果（1）978例羊水和82例外周血样本PCR-STR检测全部成功，7个STR位点多态信息联合分析，以检出2个位点面积比或强度为1：1：1三条带；或1个位点1：1：1三条带，同时有2个位点面积比或强度为1：2或2：1两条带为DS基因诊断标准，共检出DS阳性40例，其中羊水14例阳性，外周血26例阳性。（2）羊水细胞培养染色体核型分析成功961例（98．3％），17例培养失败（1．7％），检出异常染色体核型44例（4．6％），其中14例为DS核型，包括12例标准DS核型，1例易位DS核型，1例嵌合DS核型。17例培养失败羊水经脐带血染色体分析证实均为正常核型。（3）82例可疑DS患者外周血培养全部成功，检出异常染色体核型30例（36．6％），其中26例为DS核型，包括22例标准DS核型，4例易位DS核型；其它异常核型4例。（4）PCR—STR法对7个STR位点联合分析，单例样本可检出1～4个位点为1：1：1三条带，或可见2～4个位点为面积比率或强度比为2：1或1：2的两条带。羊水和外周血样本DS基因诊断结果与细胞培养染色体核型分析诊断结果完全一致，PCR—STR法快速产前基因诊断DS筛查的灵敏度为100％，未发现假阳性和假阴性结果。（5）7个STR位点杂合率在0．624～0．812，D21S2039和D21S1412位点杂合度最高（〉0．80），D21S1411和D21S1432位点杂合度较低（d0．70）。D21S11和D21S2039位点检出1：1：1三条带比率最高（≥40％），而D21S1411、D21S1432、D21S1413位点检出单一条带（纯合率）比率最高（≥30％）。结论PCR-STR法是产前诊断DS的一种快速、有效的筛查方法，7个STR位点联合分析，提供的诊断信息量大，结果准确、可靠。
Objective To assess the practicality of rapid prenatal screening for Down syndrome （DS） by polymerase chain reaction-short tandem repeat （PCR-STR） method, and to determine the genotypes of 7 STR loci in ethnic Chinese Han from Weifang region. Methods Seven STR markers （D21Sll, D21S1411, D21S1412, D21S1413, D21S1414, D21S1432 and D21S2039） from chromosome 21q22.1-22.2 region were selected. Amniotic samples from 978 high-risk pregnancies and peripheral blood samples from 82 patients suspected with DS were tested with PCR-STR. And the results were verified with G-banding analysis. Results （1） All of the 1 0 6 0 samples were successfully tested by PCR-STR. For normal individuals, thepatterns obtained by PCR-STR were two bands with 1 ： 1 area ratio or a single band. For DS cases, by contrast, the patterns revealed either three bands with area ratio of 1 ： 1 ： 1 for two STR loci, or three bands with area ratio of 1 ： 1 ： 1 for one STR loci and two bands with 2 ： 1 or 1 ： 2 area ratio for two STR loci. Based on analysis of the 7 STR markers, 14 amniotic fluid samples and 26 peripheral blood samples were regarded as DS positive. （2） For the 978 amniotic fluid samples, cytogenetie analysis was successful in 961 （98.3%）, among which 44 had an abnormal karyotype. These included 14 trisomy 21 （12 standard type, 1 mosaicism and 1 translocation）. 17 cases which failed amniocytic culture were normal upon fetal blood karyotyping. （3） Cytogenetic analysis was successful in all of the 82 peripheral blood samples, and has identified 30 （36. 6%） abnormal karyotypes, among which 26 were trisomy 21 （including 4 with translocation form）. （4） For DS positive cases, STR 1-4 showed three bands with area ratio of 1 ： 1 ： 1, or there were 2-4 loci with two bands with an area ratio of 2 ： 1 or 1 ： 2. All of the DS cases detected by PCR- STR were confirmed by karyotyping. （5） All of the 7 selected loci were informative, with their degrees of heterozygosity ranging between 0. 624 and 0. 812. D21S2039 and D21S1412 had the highest heterozygosities （〉0.80）, D21S1411 and D21S1432 had the lowest （〈0.70）. D21Sll and D21S2039 showed the highest rate （≥40%） of three bands with area ratio 1 ： 1 ： 1. However, D21S1411, D21S1432 and D21S1413 markers had the highest rate of homozygosity （≥30%）. Conclusion PCR-STR assay may provide an effective alternative for rapid prenatal DS screening. The 7 selected STR markers are highly informative. The result has featured good accuracy and reliability.
出处
《中华医学遗传学杂志》
CAS
CSCD
北大核心
2013年第3期277-282,共6页
Chinese Journal of Medical Genetics
基金
基金项目：山东省卫生科技发展计划项目（2009HW097）
