Wapner博士：在产前诊断中，它用于鉴定表型，提出问题，“疾病会导致这种表型是什么？”然后，然后测试您可以测试的那些具体的东西。而且，当我说识别我通过超声说话的表型。它完全改变了，因为我们现在通过筛选或其他技术具有能力，首先识别基因型，然后我们可以使用超声来评估表型的演变。它是总共180度的开关。

旁白：欢迎来到Illumina基因组学播客，主要科学家在这里讨论他们的基因组学研究，以及基因组学如何影响他们对科学和自然的理解。这是你的主人，保罗·布罗曼。

保罗:你好呀！感谢您加入我的Illumina Genomics播客的第31集。有几种产科筛查试验，产科医生可以用来估计婴儿是否处于较高风险或具有较低风险的风险。例如，1月孕孕孕孕孕妇血液检测和超声检查称为Nuchal半透明筛查，可以估计孩子患有染色体疾病的风险，如唐氏综合症。2nd三孕酮标记血液测试可以帮助筛选染色体异常，或单倍数，如三兆癣21或18.筛选的无侵入性产前试验或nipt，也已开发出无侵入性产前试验或NIPT，以筛选产前非血浆．在NIPT中，母体血液样本提供母体DNA以及来自妊娠的DNA，可以使用下一代测序或NGS分析。所有这些选择，产科医生如何确定最适合其患者的产前筛查类型？患者如何决定哪种产前筛查测试（如果有的话）是对的？而且，如何在胎珠诊断测试中贴适用的产前筛查试验？为了帮助挑战所有这一切，我们由哥伦比亚大学欧文医学中心和生殖遗传学总监研究副主席罗纳德J.Wapner副主席罗纳德J.Wapner博士。 He’s an internationally known physician and researcher specializing in reproductive genetics, and he pioneered the development of chorionic villus sampling, or CVS. Dr. Wapner, thanks for joining us on the podcast first of all, I know you're really busy. And I've read that you've been doing this, you've been active for over 30 years.

Wapner博士：我去过，是的。

保罗:您可能在生殖遗传学中看到了很多发展。因此，从全面的角度来看，如何在这30年内发育产前遗传学测试？直到这一刻，你开始练习的时候的护理标准是什么？该领域如何发展？

Wapner博士：发生了大量的变化。首先，大约50年前有一个观察你可以取羊水样本你可以观察液体中的染色体。大约在同一时间，我们意识到与唐氏综合症相关的额外染色体也会带来健康后果。还有一些讨论如何处理这一功能,和美国国立卫生研究院共识会议,决定的风险,使用某些染色体异常的风险的知识像唐氏综合症三倍体13到18岁,妈妈的年龄增加而增大。然后我们讨论了如何对人群进行筛查。

保罗:这是50年前的？

Wapner博士：这是大约50年前。是的。讨论有很多因素。患有染色体异常具有儿童或胎儿的风险随着产妇年龄而增加。但这并不是在任何年龄突然增加。作为一个老年人，她的风险变得更高。所以首先必须决定一个女人应该多大了，在我们提供具有产前测试的机会之前，这次是由羊膜穿刺内完成的。羊膜穿刺术也刚刚被调查，超声甚至没有被发现。因此，我们盲目地完成了早期的amios，所以人们不得不评估程序的风险，因为他们有一个程序进行了一次，所以可能会失去怀孕。没有许多实验室甚至正在做核型化，所以我们无法向大家提供这一点，因为资源有限。 So the decision was made that a woman who is 35 or older at the time of delivery had a high enough risk of having a pregnancy with chromosome abnormality to warrant doing this new diagnostic test which was called amniocentesis. The risks of which were still being investigated. Ultrasound came along, and we were now able to see where the heck we were putting the needle in. So the procedure became safer. But still, approximately five to 15 percent of women having children during that period had been 35 or older. That number has increased, so it's now closer to 15 percent. At the time it was much lower. So we were doing or offering amnios to approximately five to 15 percent of women. The question then became twofold. Number one, is there some way we can perform procedures on less women? And number two, we were only identifying women at risk who were 35 or older, yet although they had the higher risk, there still were down syndrome pregnancies occurring in younger women. About that time, we realized that there were blood markers or difference in hormone, or endocrine, or protein levels in the blood of some women carrying children with these chromosome abnormalities. And then we began to take advantage of that, and screening then changed from screening by just asking how old a woman was and that would be her screening test, to then being able to add her age to levels of biochemicals, to some ultrasound findings, et cetera. So that matured over time as the markers became better. So, in the beginning when we were offering procedures to just women 35 or older, every woman that had an amniocentesis only had about a one in a 100 probability that that fetus was affected, and we only identified 30 percent of affected cases. As we add markers, we were able to decrease that number so that a woman's risk became as low as one in 20 to 1:25. But by that I mean that every woman that elected to have a diagnostic procedure had about a one in 25 risk that the fetus was affected as opposed to one in 100 when it was age alone. We also were then able to increase the number of affected pregnancies from as I said, 30 percent with age alone. But with the best in biochemical and ultrasound markers, we now could identify 70 or 80 percent. So Over that time we've been much better able to identify the couples that were at risk for having an affected pregnancy. The other thing that happened simultaneously was we now had chorionic villus sampling, whereas amniocentesis was done around 16 weeks and in the beginning, it took four or five weeks to get results. So women were halfway through their pregnancies before they were getting information. With CVS or chorionic villus sampling, which samples the placenta in the first trimester, we now could get results by 12 or 13 weeks, which made a gigantic difference in patients’ reproductive options if they had an abnormal pregnancy. More importantly, we could reassure women everything was fine much earlier. That was what was going on while we were doing karyotypes and looking at chromosomes under the microscope. The next revolution was the introduction of molecular cytogenetics. So rather than looking at the chromosomes, we were able to break them into small molecular pieces and do things like microarrays. With microarrays, we were able to identify much smaller missing or overrepresented pieces, microdeletions and micro duplications. While that was very interesting from a laboratory standpoint, but we then had to figure out what's the clinical implications of that. In the clinical genetics arena, once they could do that, they found that there were a lot of children who had previously unknown causes of developmental delay, dysmorphic features, etc. And about 15 to 20 percent when they were tested for these sub microscopic findings, that was found to be the etiology. So we began to recognize sub microscopic syndromes and sub microscopic causes of developmental delay and problems like that. So now the question became, should we introduce this into the testing paradigm when you do amnio or CVS? So there have been studies that have now shown that of all women, no risk whatsoever, about one to one and a half percent will carry some of these small micro deletions or duplications, also called copy number variants. So individuals began when they did diagnostic procedures like amnio or CVS, began to look for these. Now the last change which occurred started about 10 years ago, but really maybe six or seven was noninvasive prenatal testing. Although amnios and CVS dramatically reduced their risk, as they said it was one percent when we started doing it without ultrasound. The risk of losing a pregnancy because you have one of these procedures is somewhere between one in 700 to one in a thousand, almost a tenfold in improvement, but still it had a risk. So patients were faced with the decision of whether or not they were willing to take that risk to get the genetic information. Along came noninvasive prenatal testing, in which we could draw a sample of blood from the mother. We realized that about 10 to 20 percent of the DNA in that sample from the mother was fetal DNA, and then using sequencing techniques, which I believe we'll talk a little more about in the future. Using sequencing techniques, we could identify which pregnancies had Down syndrome without having to do a procedure. Again, just as with every new test, we had to figure out how it compared to what was being done previously. And with noninvasive prenatal screening, we were able to go from around the 80 to 85 percent detection rate of the abnormal number of chromosomes to 99 percent. So we can identify 97 to 99 percent of Down syndrome pregnancies. More importantly as I said, we started by offering testing to 15 percent of women because they were maternal age. As screening got better, that number went down to three percent, but still that's a large number of 'false positives.' So with noninvasive DNA testing from the mom's circulation, one in 1000 to one in 10,000 false positives occur. So we dramatically decrease the number of patients that would need diagnostic testing to confirm with the blood shows.

保罗:有趣。他说我想要强调的一点是你谈到了非侵入性产前检查，但你把它称为筛查。我想知道你能否谈谈筛查和诊断测试的区别。

Wapner博士：是的，这是非常重要的一点。筛查测试是一种旨在对整个人群进行的测试，目的不是诊断问题，而是确定问题风险最高的人群。我们用年龄筛选，用化学物质筛选，用DNA筛选。但这不是诊断测试。有少量的假阳性，筛查测试显示你处于高危状态，怀孕完全正常，而假阴性测试显示一切正常，但事实并非如此。因此，筛查测试可以识别那些风险高到应该接受诊断测试的个体。一般来说，诊断测试的风险略高，成本略高，复杂度略高。所以你不能为所有400万的新生儿提供诊断测试。因此，筛查测试有助于我们识别那些有风险的妊娠，以及那些比诊断测试风险更高的妊娠，以确认胎儿确实受到筛查测试的影响。

保罗:关于筛查测试，我想说的另一件事是你提到的非侵入性产前筛查的候选者比高危患者要高。就你所见的病人类型而言，你会建议什么样的病人接受这种筛查呢?是每个人还是只有特定年龄的病人?

Wapner博士：每个女人，我的意思是美国ob / gyn的美国学院，实际上现在的护理标准是，每个女人都被提供有机会让她怀孕筛查常见的染色体异常。还有一点转换。有些人仍然具有化学和超声评估。有些人已经搬上了并开始得到非侵入性DNA测试，但每个女人都应该提供。实际上是诚实的，它靠近护理标准的靠近不提供它。现在，这并不意味着每个女人都应该得到它。有很多人只是不希望那种不同原因的信息，但他们需要了解其可用性和可能性。美国Ob / Gyn学院仍然不仅说，而且每个女人都应该提供诊断测试，CVS或羊膜穿刺。而且女性需要咨询或通知筛查和诊断之间存在差异。但是，如果一个女人说，“我想要更多信息，我想找到那些微扫描和这些微套法。我不想冒任何风险，”然后他们可以选择进行诊断测试。 So really every pregnant woman needs to be informed of this. Not everybody has it, probably about half make that decision. Probably a little bit over half now. But yeah it involves every pregnant women.

保罗:哇。因此，如果是这种情况，你刚才提到了一些关于提供一些咨询和一些指导来帮助女性做出决定的事情。如果有400万个怀孕，这是很多咨询。那么你如何处理这个？您如何将患者留给您的患者并描述这些不同的技术？

Wapner博士：你击中了要害。当我说咨询时，我偶然发现了这个词，然后我把它切换到教育。遗传咨询是一个真正深入讨论与个体患者非常相关的遗传问题。有大约3000个遗传咨询师可用。其中许多人不做生殖咨询。

保罗:而且，无论如何，这不是一个大数字。

Wapner博士：没有。因此，对于400万个出生，您无法让每个人都成为遗传咨询，但他们不需要咨询。许多女性需要什么是教育。我的风险是什么，有什么可用的技术？你可以用多种不同的方式做教育。一种方法是每一位在第一个三个月看到他的病人的医生都告诉她并有了这次讨论。平均产科医生在每次访问约15分钟内看到OB患者，特别是第一次访问，他们必须谈论在怀孕期间吃什么，需要做什么血液测试，那么早产的风险如何？你与办公室取得联系，你如何支付账单？它真的很容易到那些不可能与患者交谈这一点。因此，我们真的需要并开发了其他技术，现在有致力于教育女性对产前筛查选择的网站及其产前风险。并且围产期质量基础绰号PQF制定了一个名为宝石的过程，这是潜在的产科医生所提供的遗传教育模块，以便他们在你来看看我之前或者甚至在第一次访问之前对他们的病人说 to this website. It has a very short 20 or 30 minute overview of the risks. But then the woman has the option of going into more detail if she wants that. She then can type in any question so that when she gets to her physician's office, she can have those questions answered. Some patients won't be sure what they wanna do. They need to see the genetic counselor. So, we've not only streamlined the most important patients to test. We've also streamlined the patients that need the real long discussion. Because for some patients this is a very difficult decision.

保罗:对。我提到有一些有风险的患者。对于那些患者来说，我猜这是对测试种类的更容易决定。但对于一个平均风险女人的人来说，当他们试图决定他们应该做些什么样的测试或筛查时，您认为他们正在寻找哪些信息？

Wapner博士：我会缩小讨论范围因为我还会讲到其他的事情，但我们现在特别讨论的是女性生下一个有染色体问题的孩子的风险比如21,18,13三体。所以他们真的需要了解生孩子的风险。他们需要了解还有其他可以诊断的遗传疾病。他们需要了解诊断检测的可用性，以及筛查每种检测的风险和益处。换句话说，他们必须在一个有更多信息的诊断测试和一个不需要程序的非侵入性测试之间做出选择。简而言之，这就是病人在筛查染色体异常时必须了解的。除了这些染色体异常是什么，我们还在讨论，因为我们都熟悉医学和遗传学。如果我们说你有唐氏综合症的风险，每个人都知道这意味着一个额外的21号染色体，那就是21三体。但是，如果你告诉一个女人你要做的血液测试是为了寻找唐氏综合症，而不向她解释这意味着什么，这是不行的。因为很多人把唐氏综合症这个词和任何患有遗传疾病的孩子联系起来，他们没有理由不应该这样做。 So like if I said to you go get me a coke, you would bring me a brown soda. So I think that patients in making that decision have to understand that there are many more genetic disorders than just Down syndrome. For instance, a 40 year old woman because the risk increases with her age, Down syndrome is really what she needs to worry about. But for a 25 year old woman, her risk of having one of those smaller copy number variants is two or three times more frequent than Down syndrome. So they very well need to understand what their risks are, and these websites have that kind of information. Why I wanted to narrow the discussion because another risk that we've now begun to screen for are risks of having what are called Mendelian disorders. They're not caused by any number of chromosomes, but they're caused by a specific change, not only in a gene, in a tiny little part of the gene. And each of us carry somewhere around 12 genes that are abnormal. Well most of these aren't important because they are only problematic if their partner has a problem in that same gene. So individuals that have this, they're inherited in what's called an autosomal recessive way in which both parents need to be carrying one of these errors in a gene. And then only when couples both have the same issue, then they have a chance of having an affected child. And about 10 to 15 percent of all admissions to children's hospitals are caused by genetic diseases. So the ability to identify at risk pregnancy, and I don't want to make it sound like if both parents are carriers that their only option would be if they have an affected child to terminate the pregnancy. Because knowing some of these disorders before birth allows the neonatologist to treat them. We can sometimes modify the course in utero. So we're now showing that identifying a genetic disease in a child is really important, particularly if a child in intensive care nursery who's having severe problems like shock or coma, etc. Some people were actually going to sequence those children as the first test.

保罗:这有点类似于研究的情况。很多科学家喜欢这些大数据基因组方法的原因是它没有偏见，所以它给了他们以前没有预料到的基因的欣赏。听起来在临床环境中是类似的。这种不偏不倚的方法能让你了解微缺失的临床表现如果你只是专门寻找三体，你可能不会知道。

Wapner博士：毫无疑问，这在产前诊断中是正确的，正如你提到的，我已经做了很长时间了。

保罗:30年。

Wapner博士：在产前诊断中，它通常是识别表型，问问题，“什么样的疾病可以导致这种表型？”然后测试那些你可以测试的特定东西。而且，当我说通过超声波识别我所说的表型时。它完全改变了，因为我们现在有能力通过筛选或其他技术，首先确定基因型，然后我们可以使用超声波来评估表型的演变。这是一个180度的开关。我想，如果我在五年后和你们谈话，你们对我说同样的问题，什么发生了变化，变化将是我们从表型开始，看它是否是一种遗传病，确定它是一种遗传病，然后看表型的表现是什么，完全改变。

保罗:是的，这完全相反。所以有一件事你说我想谈论一点点是你用非侵入性产前筛查说，例如，在确定三重子21时，有99％的成功率。

Wapner博士：这是正确的。

保罗:这就是预测价值的概念。所以99%有效的筛查，如何转化为21三体的检测或非侵入性产前筛查的检测是否会导致一些需要治疗的临床结果?

Wapner博士：是的，我认为你的问题很重要。人们有时会感到困惑。99%是敏感度。这意味着在所有21岁三体的孕妇中，这种筛查测试将识别出百分之九十九的人。这并不意味着一个阳性的妇女有99%的机会她的胎儿也有，因为有假阳性和假阴性。所以阳性预测值考虑了女性在接受检测前的风险。所以如果一个40岁的女性血液检测呈唐氏综合症阳性，很有可能是唐氏综合症，因为她有患唐氏综合症的风险。但如果一名20岁的女性在同样的检测中呈阳性，则有可能在2000年得一次。所以阳性检测更有可能是假阳性而不是真的受到影响。21三体，因为它占99%，不是一个完美的例子。 But for instance, trisomy 18 in which we only identify 97 or 98 percent and have a few more false positives. As I said, a 37 year old woman with a positive test is like 99 percent that it's trisomy 18, but in a younger woman, she's got more than a 50 percent chance that that test is actually a false positive test.

保罗:哇。这是相当高的。

Wapner博士：并且性染色体异常具有额外的X染色体或缺失的X染色体，灵敏度和假阳性率较低。所以它真的具有相对较少的积极预测价值。如此敏感和特异性是公共卫生人员想要知道的。我有一个新的测试。有多少例案例是为了识别？但对于史密斯夫人或琼斯夫人，她想知道她是否有积极的考验。什么是积极的预测价值？我的风险是什么？我认为人们知道差异是非常重要的，因为一个25岁的女性更有可能没有问题而不是出现问题，从不考虑在筛选测试上做出不可逆转的决定。她绝对拥有，良好的每个人都必须具有诊断测试，但阳性测试的风险取决于患者的年龄。

保罗:有趣。在我到达最后一个问题之前，我只是想回到你提到的东西，这是你正在寻找的遗传扰动类型。所以我们谈到了一些这些非血磅，所以非侵入性产前筛查。什么是最有效的遗传异常类型，这些遗传异常与该测试筛选？

这些

保罗:对，我读到总体上，它们比三术21更常见。

Wapner博士：但每个人都少，而且一个非侵入性筛查的方式，我会说一句话，你实际上必须瞄准你的筛选。因此，当您筛选Trisomy 21时，您可以计算母亲在母亲循环中漂浮的DNA碎片。由于微缺失和重复可以来自许多染色体，因此它现在不可行。现在你可以，如果你估计数千个数千件碎片，识别微小的小缺失的碎片，但你真的不能这样做，因为你只是无法排序。它只是花费无限的金钱。当你正在寻找一个整个染色体时，你从整个染色体上都有所有的碎片，而不仅仅是染色体的片段。这就是为什么我们能够做到这一点。因此，每个实验室都现在在他们的面板上提供一些微扫描，但只有一个存在的小型数量存在。

保罗:有趣。好吧。在你回去工作之前，最后一个问题。什么让你兴奋

Wapner博士：这是我的日常工作。

保罗:什么是关于遗传测试的未来令人兴奋的是，特别是，您认为未来几年是在非侵入性产前筛查的发展方面举行的，因为这变得如此重要？

Wapner博士：筛查不同基因疾病的能力在不断提高，我们对此已经谈了很多。我们已经从无创地识别整个染色体，随着测序的改进，我们正在向小片段染色体迈进。最后一个方面是能够无创地对胎儿进行排序，查看每个碱基对。你可以做到。你今天绝对可以做到。这样做的可行性和生物学合理性已经被证明。这不能作为一个临床过程。人们是否愿意把它作为一个临床过程也是一个问题，因为它太劳动密集了。他们第一次对胎儿进行测序时花了六个月到一年的时间。你不能等待结果。但是，这项技术将会出现，因为现在当我们研究无创检测时，我们有胎儿DNA、10%和90%的母体DNA的混合物。因此，我们必须仔细检查每一个片段，不知道它是来自胎儿还是来自母亲，然后进行数学计算，问是否有太多来自胎儿21号染色体的片段？如果我们能找到一个标记，使我们能够区分来自胎儿的片段和来自母亲的片段，游戏就完全改变了，因为我们可以分离胎儿DNA，有两种方法可以做到这一点。分离胎儿的片段实际上比母体的片段小一些，所以你可以根据大小来做，但大多数我们根本没有谈论这个，但是生物信息学，计算机是如何让我们做事情的，有一些想法认为有一些生物信息学，微妙的DNA变化可以帮助我们区分这些。那可能就是我们要去的地方。一旦我们能做到这一点，我们就能对胎儿进行排序。现在，我并不是说这样做是正确的。争论的焦点是你应该对胎儿的DNA了解多少？但我们必须考虑到，出生缺陷的主要原因之一是胎儿结构异常、先天性出生缺陷。百分之三。在普通人群中，唐氏综合征的一般风险为800分之一。我们可以通过泛种族筛查发现的隐性疾病的一般风险为500分之一。微缺失可能为90分之一。出生缺陷发生率为3%。其中绝大多数是由单碱基对突变引起的，它们是从头突变。所以你不能在屏幕上看到他们。所以它们只发生在胎儿身上，不一定发生在父母身上。因此，无创性地，我们可以通过携带者筛查消除大多数隐性疾病。我们可以得到一些主要的染色体异常，但900磅的大猩猩是这些先天缺陷的遗传病因。因此，这将从我们不打算寻找一切开始。我们将要寻找这些与最常见的出生缺陷相关的最常见的基因，我们可以开始寻找这些基因。事实上，已经有一家公司进行了一项检测，检测胎儿中30种最常见的基因突变。他们说的是对整个人群进行筛查。可能发生的最后一件事，我们讨论了无细胞DNA，我提到了将其与母体DNA分离的困难，这使分离变得更困难。有人继续致力于从母体循环中提取胎儿胎盘细胞、滋养层细胞。他们变得很好，但并不完美。如果你能得到三个胎儿细胞，那只是胎儿DNA。你可以放大DNA，你可以分析DNA，如果我们能得到细胞，你可以得到所有这些的答案。我们会这样做吗？当我说50年前，30年来，我一直以各种方式试图找到细胞。他们很坚强。在你抽取的一整管血液中，可能有10到30个这样的细胞。所以它们真的很少出现。但是显微切割、显微分离技术越来越好。这是可以想象的。这就是我们要讨论的，诊断单碱基对变异。

保罗:令人惊叹的。瓦普纳博士感谢您的加入。我认为我们的听众对什么是产前基因检测以及它在临床上的应用有很好的理解。感谢您加入我们的Illumina基因组学播客。

Wapner博士：这是我的荣幸。

保罗:据Acog称，每个女人都应该提供有机会让她怀孕筛查常见的染色体异常。The advent of NGSbased NIPT has expanded the options for prenatal chromosomal screening for women in pregnancy, and NIPT is 99% sensitive for detecting trisomy 21. It’s important to understand that NIPT false-positive results are more frequent among low-risk women than those at high risk, so a positive screening test needs to be confirmed by a diagnostic test. If you’re interested in learning more about GEM for education of patients and physicians about prenatal screening and testing options, visit gem.perinatalquality.org. If you liked today’s show, please subscribe on Apple Podcasts or Google Podcasts. Join me next time, when I’ll be talking with Dr. Sam Sternberg, Assistant Professor of Biochemistry and Molecular Biophysics at Columbia University. We’ll be discussing CRISPR-Cas biology and genome engineering - here on the Illumina Genomics Podcast.