Polar body analysis by array comparative genomic hybridization accurately predicts aneuploidies of maternal meiotic origin in cleavage stage embryos of women of advanced maternal age
Polar body analysis by array comparative genomic hybridization accurately predicts aneuploidies of maternal meiotic origin in cleavage stage embryos of women of advanced maternal age
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DOI：
10.1093/humrep/det053
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发表时间：
2013-05-01
影响因子：
6.1
通讯作者：
Handyside, Alan H.
中科院分区：
文献类型：
--
作者：
Christopikou, Dimitra;Tsorva, Erika;Handyside, Alan H.
阵列比较基因组杂交（阵列CGH）分析第一极体（PB 1）和第二极体（PB 2）在预测高龄产妇卵裂期胚胎中母体减数分裂起源的非整倍性方面的准确性如何？几乎所有在卵裂期胚胎中检测到的非整倍性都与极体中的拷贝数变化有关（93），除一个（98.5）外，所有都被预测为非整倍性。少数拷贝数变化（主要在PB 1中）并不导致胚胎的预测变化，但其中许多是小拷贝数变化，可能是人为因素。染色体非整倍性是妊娠失败和流产、异常妊娠和活产的主要原因。大多数非整倍体是母体减数分裂起源，并在绝经前十年呈指数增长。一项初步研究表明，在高龄产妇中，极体分析预测的染色体状态与相应的受精卵之间的一致率很高。对正常受精的成熟卵母细胞进行极体活检和阵列CGH分析，以确定减数分裂中的分离错误，然后分析相应的卵裂期胚胎（n 34），20对要求进行非整倍体筛查的夫妇（平均标准差为39.3岁）接受了16个控制性超排卵和7个自然IVF周期。PB 1和PB 2分别在卵胞浆内单精子注射（ICSI）前和确认正常受精后从成熟卵母细胞中活检。阵列CGH用于检测染色体拷贝数的变化，并预测相应胚胎的非整倍体。移植两极体中拷贝数正常的胚胎，但在ICSI后第3天，通过阵列CGH在去除染色体后整体分析了34个卵裂期胚胎，其中大多数被预测具有一个或多个母体减数分裂起源的非整倍体。在这些胚胎中检测到74个非整倍体。69（93）例非整倍体与极体拷贝数变化相关，其中68（98.5）例被预测为非整倍体。此外，PB 1/PB 2中20（95）个染色单体增加/丢失的平衡组合中有19个准确预测了相应胚胎中的正常拷贝数。然而，极体中的17（12）个拷贝数变化未导致预期结果，包括12个非整倍体的假阳性预测。其中大多数涉及拷贝数变化，其小于整个染色体或染色单体不平衡的预期变化，并且在PB 1中发生的频率显著高于PB 2（P 0.0005）。在PB 2中仅有少量拷贝数变化的另外三个胚胎和一个部分染色体丢失的胚胎都被证实为整倍体。准确的假阳性和阴性率需要对整倍体和非整倍体胚胎进行随访，利用分子遗传标记可以独立检测非整倍体并鉴定其来源，极体活检和阵列CGH分析可以有效、准确地预测大多数卵裂中的非整倍体阶段胚胎。然而，在得出结论认为存在真实的拷贝数变化之前，应始终将比率变化的大小（尤其是在PB 1中）与X染色体变化进行比较。P.S.还有A.H.H.分别由英国剑桥的BlueGnome有限公司全职和兼职雇用。
How accurate is array comparative genomic hybridization (array CGH) analysis of the first polar body (PB1) and second polar body (PB2) in predicting aneuploidies of maternal meiotic origin in the cleavage stage embryos of women of advanced maternal age?Almost all of the aneuploidies detected in cleavage stage embryos were associated with copy number changes in the polar bodies (93) and all but one (98.5) were predicted to be aneuploid. A minority of copy number changes (17), mainly in PB1, did not result in the predicted changes in the embryo, but many of these were small copy number changes, which are likely to be artefacts.Chromosome aneuploidy is a major cause of pregnancy failure and loss, abnormal pregnancy and live births. Most aneuploidy is of maternal meiotic origin and increases exponentially in the decade preceding the menopause. A pilot study demonstrated a high rate of concordance between the chromosomal status predicted by polar body analysis and the corresponding zygotes in women of advanced maternal age.Polar body biopsy and array CGH analysis of mature oocytes, which fertilized normally, to identify segregation errors in meiosis, followed by the analysis of the corresponding cleavage stage embryos (n 34), in a consecutive series of stimulated and natural IVF cycles in women of advanced maternal age.Twenty couples requesting aneuploidy screening (mean SD of maternal age 39 3 years) had 16 controlled ovarian hyperstimulation and 7 natural IVF cycles. PB1 and PB2 were biopsied from mature oocytes, prior to intracytoplasmic sperm injection (ICSI) and following confirmation of normal fertilization, respectively. Array CGH was used to detect chromosome copy number changes and to predict aneuploidy in the corresponding embryos. Embryos with normal copy number in both polar bodies were transferred but, 34 cleavage stage embryos, most of which were predicted to have one or more aneuploidies of maternal meiotic origin, were analysed in whole after removal of the zona by array CGH, on Day 3 post-ICSI.Thirty cleavage stage embryos, predicted to have one or more aneuploidies, were all confirmed to be aneuploid (100 concordant). Seventy four aneuploidies were detected in these embryos. Sixty-nine (93) aneuploidies were associated with copy number changes in the polar bodies and 68 (98.5) of these had been predicted to be aneuploid. Also, 19 of 20 (95) balanced combinations of chromatid gain/loss in PB1/PB2 accurately predicted normal copy number in the corresponding embryos. However, 17 (12) copy number changes in the polar bodies did not result in the expected outcome, including 12 false positive predictions of aneuploidy. Most of these involved copy number changes that were smaller than would be expected for whole chromosome or chromatid imbalance and occurred significantly more often in PB1 than PB2 (P 0.0005). Three other embryos with only small copy number changes and one embryo with a partial chromosome loss in PB2, were all confirmed to be euploid.Accurate false positive and negative rates will require follow-up of both euploid and aneuploid embryos, ideally using molecular genetic markers to detect aneuploidy independently and to identify their origin.Polar body biopsy and array CGH analysis is efficient and accurately predicts most aneuploidies in cleavage stage embryos. However, the size of the ratio shifts, particularly in PB1, should always be compared with the X chromosome shift before it can be concluded that there is a real copy number change.Study funded by Embryogenesis, Athens. P.S. and A.H.H. are employed full time and part time, respectively, by BlueGnome Ltd, Cambridge, UK.