Allen S K, Luharia A, Gould C P, MacDonald F, Larkins S, Davison E V
West Midlands Regional Genetics Laboratory, Birmingham Women's Hospital, Edgbaston, Birmingham B15 2TG.
Prenat Diagn. 2006 Dec;26(12):1160-7. doi: 10.1002/pd.1582.
QF-PCR analysis can be used as a rapid test to diagnose primary trisomy in prenatal samples. Mosaicism in CVS detected by QF-PCR has previously been reported; however, no case has so far been reported in which the QF-PCR result was completely discrepant to that of the karyotype analysis from a long-term culture.
A CVS, referred because of a high serum screening risk of 1:10 for Down Syndrome and 1:110 for Edwards Syndrome, was tested by QF-PCR analysis and chromosome analysis of cultured cells. Subsequent analyses were carried out on a follow-up amniotic fluid sample and foetal tissue samples.
Conflicting results were obtained between QF-PCR analysis on two independent fronds from the chorionic villi and chromosome analysis on cultured CVS. Cytogenetic and molecular analysis on a subsequent amniotic fluid sample indicated trisomy 18 with no evidence of mosaicism. Analysis of follow-up tissue confirmed trisomy in a foetal skin sample and mosaicism for trisomy 18 in four placental sites tested.
We report here an apparently normal CVS QF-PCR result that was completely discrepant with the trisomy 18 positive karyotype result on long-term culture. This has important implications regarding our current testing protocol.
QF-PCR分析可作为一种快速检测方法，用于诊断产前样本中的原发性三体。此前已有关于QF-PCR检测到的绒毛取样（CVS）中的嵌合体的报道；然而，迄今为止，尚未有QF-PCR结果与长期培养的核型分析结果完全不一致的病例报道。
对一份因唐氏综合征血清筛查风险为1:10、爱德华兹综合征血清筛查风险为1:110而送检的CVS进行了QF-PCR分析和培养细胞的染色体分析。随后对一份随访羊水样本和胎儿组织样本进行了分析。
对绒毛膜绒毛的两个独立叶进行的QF-PCR分析与培养的CVS的染色体分析结果相互矛盾。对后续羊水样本进行的细胞遗传学和分子分析表明为18三体，无嵌合体证据。随访组织分析证实胎儿皮肤样本中存在三体，在检测的四个胎盘部位存在18三体嵌合体。
我们在此报告了一例CVS的QF-PCR结果看似正常，但与长期培养的18三体阳性核型结果完全不一致的病例。这对我们当前的检测方案具有重要意义。
