染色体易位的植入前遗传学诊断

目的 观察染色体平衡易位和罗伯逊(罗氏)易位基因携带者夫妇进行植入前遗传学诊断(PGD)后的胚胎染色体遗传特征和胚胎着床、妊娠情况,探讨PGD在染色体易位基因携带者夫妇实现正常生育中的意义.方法 用荧光原位杂交(FISH)技术对36对夫妇的胚胎进行PGD,其中14例为染色体平衡易位(平衡易位组),22例为染色体罗氏易位(罗氏易位组),并对诊断结果和胚胎着床、妊娠情况进行分析.结果 36例患者共活检胚胎253个,成功诊断胚胎225个,成功率为88.9%(225/253),获得可供移植的正常或平衡的胚胎共58个.平衡易位组和罗氏易位组PGD后胚胎着床率分别为36%(5/14)和14%(6/44),临床妊娠率分别为4/9和26%(5/19).结论 PGD可有效诊断胚胎染色体平衡易位和罗氏易位,避免反复流产和不必要的非意愿性终止妊娠,并获得理想的胚胎着床率和临床妊娠率.     

父源性染色体异常胚胎植入前遗传学诊断的最新研究进展

染色体异常是导致男性不育的一个重要原因。不同类型染色体异常的生殖细胞进行减数分裂时形成不同类型的配子,且各种异常配子所比例的实际值与理论值不相符。另外,正常胚胎率与正常配子率也不一致。本文对染色体结构异常(相互易位、罗伯逊易位、倒位、染色体复杂性重组)和数目异常(性染色体数目异常、常染色体数目异常)男性的正常精子率以及正常胚胎率进行综述。     

促排卵方案对染色体易位携带者胚胎植入前检测结局的影响

目的探讨促性腺激素释放激素(Gn RH)激动剂长方案与拮抗剂方案对染色体易位携带者胚胎植入前检测(PGT)结局的影响。方法回顾性分析2015年1月至2017年12月于中国医科大学附属盛京医院行胚胎植入前检测助孕的226例染色体易位携带夫妇的临床资料,根据促排卵方案分为长方案组(174例)和拮抗剂组(52例),对比两组间Gn用量、Gn天数、胚胎质量、正常和平衡胚胎数、每移植周期临床妊娠率、流产率、持续妊娠率等差异。结果长方案组和拮抗剂组的获卵数、MⅡ卵子数、正常受精率、卵裂率、囊胚形成率、优质囊胚数、活检囊胚数、正常和平衡胚胎数、每移植周期临床妊娠率、流产率、持续妊娠率和累积持续妊娠率差异均无统计学意义(P0.05)。而拮抗剂组Gn用量(2100 U vs. 2400 U)和天数(9 d vs. 10 d)显著少于长方案组(P0.05)。结论在胚胎植入前检测助孕过程中,长方案与拮抗剂方案的胚胎质量和妊娠率无明显差异,但拮抗剂方案在Gn用量和天数上占有优势。     

荧光原位杂交技术不同方案用于染色体易位携带者胚胎植入前遗传学诊断的效率比较

目的 探讨荧光原位杂交(FISH)技术不同方案用于染色体易位携带者胚胎植入前遗传学诊断(PGD)的效率.方法 根据FISH检测方案的不同进行分组:采用全染色体涂抹探针对染色体易位携带者8个周期的109个卵母细胞第一极体进行诊断(A组),采用联合端粒和着丝粒探针对染色体易位携带者29个周期的357个卵裂球进行诊断(B组),比较两组的活检成功率、固定时细胞丢失率、无核细胞数等.结果 A组的109个卵母细胞中72个受精,受精率为66.1%(72/109),B组的357个卵裂球中304个受精,受精率为85.2%(304/357),A组的受精率显著低于B组,差异有统计学意义(P<0.05).固定时细胞丢失率A组为9.6%(12/104),B组为1.6%(4/252),两组比较,差异也有统计学意义(P<0.05).杂交后核的无信号率A组为11.2%(10/89),B组为3.0%(7/233),两组比较,差异有统计学意义(P<0.05).A组的诊断率为72.5%(79/109),显著低于B组的89.8%(230/256),差异有统计学意义(P<0.05).A组的临床妊娠率和胚胎植入率分别为3/7和22.2%(4/18),均高于B组的30.4%(7/23)和15.7%(8/51),但差异均无统计学意义(P>0.05).结论 FISH两种方案均可有效地进行染色体平衡易位的PGD,卵裂球PGD的诊断效率更高.     

单核苷酸多态性微阵列在染色体易位植入前遗传学诊断中的应用

染色体易位是不孕不育的重要原因之一,也是植入前遗传学诊断 （PGD）的主要适应证之一。单核苷酸多态性微阵列（SNP array）是近年用来于PGD诊断的新技术。与传统的单细胞诊断方法相比较,SNP微阵列具有更多的优点。文章从SNP array原理、SNP array PGD国内外现状及适应证、优缺点及SNP array在PGD中的应用和展望等方面进行阐述。     

单核苷酸多态性微阵列在染色体易位植入前遗传学诊断中的应用

染色体易位是不孕不育的重要原因之一,也是植入前遗传学诊断(PGD)的主要适应证之一。单核苷酸多态性微阵列(SNP array)是近年用来于PGD诊断的新技术。与传统的单细胞诊断方法相比较,SNP微阵列具有更多的优点。文章从SNP array原理、SNP array PGD国内外现状及适应证、优缺点及SNP array在PGD中的应用和展望等方面进行阐述。     

应用荧光原位杂交技术对罗伯逊易位携带者进行胚胎植入前诊断

罗伯逊易位是常见的染色体结构异常 ,患者常常表现为反复自然流产。胚胎植入前遗传学诊断 (ｐｒｅｉｍｐｌａｎｔａｔｉｏｎｇｅｎｅｔｉｃｄｉａｇｎｏｓｉｓ,ＰＧＤ) ,可以选择正常的胚胎进行移植 ,有利于获得正常妊娠从而达到优生优育的目的。我们应用荧光原位杂交 (ｆｌｕｏｒｅｓｃｅｎｃｅｉｎ ｓｉｔｕｈｙｂｒｉｄｉｚａｔｉｏｎ ,ＦＩＳＨ)方法对罗伯逊易位携带者进行ＰＧＤ ,现报道如下。一、资料与方法1.病例介绍 :患者 30岁 ,已婚 6年 ,反复自然流产 5次 ,外周血染色体核型分析为罗伯逊易位携带者 ,即 45 ,ＸＸ ,- 13,- 14, ｔ(…     

罗伯逊易位携带者进行胚胎植入前遗传学诊断6例临床分析

罗伯逊易位(Robertsonian translocation)是一种涉及2条近端着丝粒染色体(D/G组染色体)的易位类型,其断裂发生在着丝粒部位或着丝粒附近,整个染色体臂发生了相互易位,形成2条中着丝粒染色体 [1].其中由染色体短臂形成的小染色体往往丢失,虽然染色体数目减少了1条,但由于主要基因没有丢失,个体的表型是正常的.     

染色体病的植入前诊断

染色体病是一大类遗传病 ,由染色体的数目异常或结构异常所致 ,已发现的染色体病已超过 10 0 0种。现在 ,还没有有效的方法治疗此类疾病。通过羊膜腔穿刺 (ａｍｎｉｏｃｅｎｔｅｓｉｓ,ＡＣ)及绒毛膜取样 (ｃｈｏｒｉｏｎｉｃｖｉｌｌｉｓａｍｐｌｉｎｇ ,ＣＶＳ)技术获取孕中期羊水中胎儿细胞或孕早期绒毛膜滋养细胞 ,以细胞遗传学技术及荧光原位杂交 (ｆｌｕｏｒｅｓｃｅｎｔｉｎｓｉｔｕｈｙｂｒｉｄｉｚａｔｉｏｎ ,ＦＩＳＨ)技术分析胚胎的染色体组成 ,筛除异常胚胎 ,使正常胚胎继续妊娠 ,有效地减少了染色体病患儿的出生。但是传统的…     

应用荧光原位杂交技术进行植入前胚胎染色体诊断的价值

目的 初步探讨应用荧光原位杂交(FISH)技术进行植入前胚胎染色体诊断的价值。方法 对10对不孕夫妇进行植入前遗传学诊断(PGD)周期的超促排卵和卵母细胞浆内单精子注射,于受精后第3天进行胚胎活检及FISH分析,第4天选择染色体组成正常或平衡的胚胎进行移植。结果 10个PGD周期共获卵158个,对其中54个胚胎进行活检,51个胚胎获得明确诊断,诊断率为94％(51／54)。对染色体组成正常或平衡的24个胚胎进行官腔内移植,共4例获得妊娠,其中3例已足月分娩健康婴儿,1例为异位妊娠。结论 应用FISH技术进行植人前胚胎染色体诊断,是预防流产和染色体异常患儿出生的有效手段。     

Outcome of preimplantation genetic diagnosis of translocations

Objective: To review 35 cases of preimplantation genetic diagnosis (PGD) of translocations with several methods, including telomeric probes.

Design: Retrospective study.

Setting: Clinical IVF laboratory.

Patient(s): Thirty-five couples with one partner carrying a chromosomal translocation.

Intervention(s): PGD of translocation after polar-body or embryo biopsy.

Main Outcome Measure(s): Pregnancy outcome.

Result(s): Several trends were observed. First, PGD can achieve a statistically significant reduction in spontaneous abortion, from 95% to 13%. Second, the chances of achieving pregnancy are correlated with 50% or more of the embryos being chromosomally normal. Third, patients with robertsonian translocations produced fewer abnormal gametes and more pregnancies than did patients with reciprocal translocations. Fourth, a new fluorescence in situ hybridization protocol for PGD of translocations, which involves applying telomeric probes, has proved adequately reliable with a 6% average error rate.

Conclusion(s): PGD of translocations achieves a statistically significant reduction in spontaneous abortion, both for polar-body and blastomere biopsy cases. Pregnancy outcome depended on the number of normal embryos available for transfer, with patients having <50% abnormal embryos achieving the most pregnancies. Because robertsonian translocations caused fewer abnormal embryos than reciprocal translocations, they also resulted in higher rates of implantation.     

Predictability of preimplantation genetic diagnosis of aneuploidy and translocations on prospective attempts

The aim of this study was to determine if the outcomes of aneuploidy and translocation testing by preimplantation genetic diagnosis (PGD) at the 8-cell stage have a predictive value for new genetic diagnosis cycles. In total, 83 cycles (39 patients) undergoing PGD of translocations and 378 cycles (176 patients) of aneuploidy were included. Predictability, defined as having similar rate (+/-20%) of euploid embryos in the first and successive cycles, was found in 66% of patients undergoing aneuploidy testing. Predictability was found significantly more often in patients undergoing PGD of translocations (90%, P = 0.006). In addition, patients with 0, <30 or > or =30% euploid embryos in the first cycle were compared and groups 0 and <30% had significantly fewer euploid embryos in the second cycle (22-26%) than those of the group with > or =30% (37%) (P < 0.05). Patients who did not become pregnant after the first attempt were stimulated more aggressively than those becoming pregnant, producing significantly more embryos in the second than in the first cycle (P < 0.001). Therefore, correlation between euploidy rate and pregnancy rate could not be assessed objectively between cycles. In conclusion, the PGD results of a first cycle can predict the results of the second cycle, but this is likely to be of more value when the condition investigated is translocation rather than aneuploidy. The chance of pregnancy is usually related to the number of euploid embryos.     

Blastocyst trophectoderm biopsy and preimplantation genetic diagnosis for familial monogenic disorders and chromosomal translocations

OBJECTIVE: Modern in vitro fertilization practices involve transfer of embryos as blastocysts, when anabolic metabolism is well established and pregnancy rates can be maintained while transferring embryos singly to avoid multiple pregnancies. Embryo biopsy for preimplantation genetic diagnosis (PGD), however, is generally performed on day 3, when the embryo comprises just 6 to 8 cells, one or two of which are removed for testing. Implantation rates and clinical pregnancy rates have remained relatively low and a harmful effect from losing one or more cells from such early embryos has not been excluded. METHODS: We performed a sequential study involving 399 egg retrievals and 1879 embryo biopsies for patients undergoing PGD to avoid a serious monogenic disease or an unbalanced chromosomal translocation. We compared implantation and viable pregnancy rates after biopsies taken on day 3 (cleavage-stage biopsy) with biopsies delayed until day 5 or 6, when the embryo is a blastocyst and 5 or more cells can be sampled from the trophectoderm while the inner cell mass, from which the fetus develops, remains intact. All embryos were transferred as blastocysts. RESULTS: Despite fewer blastocysts than cleavage embryos biopsied and tested (3.6 compared to 6.6), implantation rates per embryo transferred were 43.4% if biopsied at the blastocyst stage and 25.6% if biopsied at the cleavage stage (P < 0.01), with ongoing or live-birth pregnancy rates per egg retrieval of 34.2% (average transfer number 1.1) for blastocyst biopsies and 25.5% (transfer number 1.6) for cleavage stage biopsies (P < 0.05, 1-tailed). The multiple pregnancy rate for monogenic disease exclusion fell from 16.7% to 2% (P = 0.04, 1-tailed). CONCLUSIONS: For exclusion of genetic disease, day 5-6 blastocyst-stage biopsies are more likely to be followed by implantation and singleton births than is the case after PGD performed on day 3.     

Successful pregnancy outcomes after preimplantation genetic diagnosis (PGD) for carriers of chromosome translocations

Reciprocal translocations are found in about 1 in 500 people, whereas Robertsonian translocations occur with a prevalence of 1 in 1000. Balanced carriers of these rearrangements, although phenotypically normal, may present with infertility, recurrent miscarriage, or offspring with an abnormal phenotype after segregation of the translocation at meiosis. Once the translocation has been identified, prenatal diagnosis can be offered, followed by termination of pregnancies with chromosome imbalance. Couples who have suffered repeated miscarriage or those who have undergone termination of pregnancy as a result of the translocation carrier status of one partner are looking increasingly to preimplantation genetic diagnosis (PGD) as a way of achieving a normal pregnancy. Similarly, infertile couples in which one partner is a translocation carrier may request PGD to ensure transfer of normal embryos after in vitro fertilization. Translocation PGD has been applied successfully in several centres worldwide and should now be considered as a realistic treatment option for translocation carriers who do not wish to trust to luck for a successful natural outcome.     

Successful pregnancy outcomes after preimplantation genetic diagnosis (PGD) for carriers of chromosome translocations

Reciprocal translocations are found in about 1 in 500 people, whereas Robertsonian translocations occur with a prevalence of 1 in 1000. Balanced carriers of these rearrangements, although phenotypically normal, may present with infertility, recurrent miscarriage, or offspring with an abnormal phenotype after segregation of the translocation at meiosis. Once the translocation has been identified, prenatal diagnosis can be offered, followed by termination of pregnancies with chromosome imbalance. Couples who have suffered repeated miscarriage or those who have undergone termination of pregnancy as a result of the translocation carrier status of one partner are looking increasingly to preimplantation genetic diagnosis (PGD) as a way of achieving a normal pregnancy. Similarly, infertile couples in which one partner is a translocation carrier may request PGD to ensure transfer of normal embryos after in vitro fertilization. Translocation PGD has been applied successfully in several centres worldwide and should now be considered as a realistic treatment option for translocation carriers who do not wish to trust to luck for a successful natural outcome.     

Clinical application of next-generation sequencing in preimplantation genetic diagnosis cycles for Robertsonian and reciprocal translocations

Purpose

The purpose of this study was to apply next-generation sequencing (NGS) technology to identify chromosomally normal embryos for transfer in preimplantation genetic diagnosis (PGD) cycles for translocations.

Methods

A total of 21 translocation couples with a history of infertility and repeated miscarriage presented at our PGD clinic for 24-chromosome embryo testing using copy number variation sequencing (CNV-Seq).

Results

Testing of 98 embryo samples identified 68 aneuploid (69.4 %) and 30 (30.6 %) euploid embryos. Among the aneuploid embryos, the most common abnormalities were segmental translocation imbalances, followed by whole autosomal trisomies and monosomies, segmental imbalances of non-translocation chromosomes, and mosaicism. In all unbalanced embryos resulting from reciprocal translocations, CNV-Seq precisely identified both segmental imbalances, extending from the predicted breakpoints to the chromosome termini. From the 21 PGD cycles, eight patients had all abnormal embryos and 13 patients had at least one normal/balanced and euploid embryo available for transfer. In nine intrauterine transfer cycles, seven healthy babies have been born. In four of the seven children tested at 18 weeks gestation, the karyotypes matched with the original PGD results.

Conclusion

In clinical PGD translocation cycles, CNV-Seq displayed the hallmarks of a comprehensive diagnostic technology for high-resolution 24-chromosome testing of embryos, capable of identifying true euploid embryos for transfer.