Rickman L, Fiegler H, Shaw-Smith C, Nash R, Cirigliano V, Voglino G, Ng B L, Scott C, Whittaker J, Adinolfi M, Carter N P, Bobrow M
University of Cambridge, Department of Medical Genetics, Addenbrooke's Hospital, Hills Road, Cambridge,UK.
J Med Genet. 2006 Apr;43(4):353-61. doi: 10.1136/jmg.2005.037648. Epub 2005 Sep 30.
Karyotype analysis has been the standard method for prenatal cytogenetic diagnosis since the 1970s. Although highly reliable, the major limitation remains the requirement for cell culture, resulting in a delay of as much as 14 days to obtaining test results. Fluorescent in situ hybridisation (FISH) and quantitative fluorescent PCR (QF-PCR) rapidly detect common chromosomal abnormalities but do not provide a genome wide screen for unexpected imbalances. Array comparative genomic hybridisation (CGH) has the potential to combine the speed of DNA analysis with a large capacity to scan for genomic abnormalities. We have developed a genomic microarray of approximately 600 large insert clones designed to detect aneuploidy, known microdeletion syndromes, and large unbalanced chromosomal rearrangements.
This array was tested alongside an array with an approximate resolution of 1 Mb in a blind study of 30 cultured prenatal and postnatal samples with microscopically confirmed unbalanced rearrangements.
At 1 Mb resolution, 22/30 rearrangements were identified, whereas 29/30 aberrations were detected using the custom designed array, owing to the inclusion of specifically chosen clones to give increased resolution at genomic loci clinically implicated in known microdeletion syndromes. Both arrays failed to identify a triploid karyotype. Thirty normal control samples produced no false positive results.
Analysis of 30 uncultured prenatal samples showed that array CGH is capable of detecting aneuploidy in DNA isolated from as little as 1 ml of uncultured amniotic fluid; 29/30 samples were correctly diagnosed, the exception being another case of triploidy. These studies demonstrate the potential for array CGH to replace conventional cytogenetics in the great majority of prenatal diagnosis cases.
自20世纪70年代以来，核型分析一直是产前细胞遗传学诊断的标准方法。尽管该方法高度可靠，但其主要局限性仍然是需要进行细胞培养，这导致获得检测结果的时间延迟多达14天。荧光原位杂交（FISH）和定量荧光PCR（QF-PCR）能快速检测常见的染色体异常，但无法对基因组进行全面筛查以发现意外的失衡情况。阵列比较基因组杂交（CGH）有潜力将DNA分析的速度与大规模扫描基因组异常的能力结合起来。我们开发了一种包含约600个大插入片段克隆的基因组微阵列，旨在检测非整倍体、已知的微缺失综合征以及大规模不平衡染色体重排。
在一项对30份经显微镜确认存在不平衡重排的培养产前和产后样本的盲法研究中，将该阵列与分辨率约为1 Mb的阵列一起进行测试。
在1 Mb分辨率下，识别出了22/30的重排，而使用定制设计的阵列检测到了29/30的畸变，这是因为包含了特意挑选的克隆，从而在已知微缺失综合征所涉及的基因组位点上提高了分辨率。两种阵列均未能识别出三倍体核型。30份正常对照样本未产生假阳性结果。
对30份未培养的产前样本的分析表明，阵列CGH能够检测从仅1 ml未培养羊水分离出的DNA中的非整倍体；29/30的样本被正确诊断，唯一的例外是另一例三倍体病例。这些研究证明了阵列CGH在绝大多数产前诊断病例中替代传统细胞遗传学的潜力。
