{"id":822,"date":"2020-09-13T23:22:16","date_gmt":"2020-09-13T20:22:16","guid":{"rendered":"https:\/\/f-genetics.com\/?post_type=test&#038;p=822"},"modified":"2024-03-01T20:18:23","modified_gmt":"2024-03-01T17:18:23","slug":"pgt-2","status":"publish","type":"test","link":"https:\/\/f-genetics.com\/en\/pgt-2\/","title":{"rendered":"PGT-A"},"content":{"rendered":"<div class=\"wp-block-genetics-row-with-tabs test__row\"><div class=\"test__col\"><section class=\"test__tabs\"><h2>Main features<\/h2><div class=\"inner\">\n<div class=\"wp-block-genetics-tabs c-tabs\"><div class=\"c-tabs__nav\"><div class=\"tabs-wrapper swiper-wrapper\"><div data-tab=\"1\" class=\"tab-link swiper-slide current\" tabindex=\"0\">Overview<\/div><div data-tab=\"2\" class=\"tab-link swiper-slide\" tabindex=\"0\">What is PGT-A<\/div><div data-tab=\"3\" class=\"tab-link swiper-slide\" tabindex=\"0\">Indications<\/div><div data-tab=\"4\" class=\"tab-link swiper-slide\" tabindex=\"0\">What it detects<\/div><div data-tab=\"5\" class=\"tab-link swiper-slide\" tabindex=\"0\">Effectiveness<\/div><\/div><\/div><div class=\"tabs-arrow arrow-prev\">\u2190<\/div><div class=\"tabs-arrow arrow-next\">\u2192<\/div><div class=\"c-tabs__contents\">\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-1 current\">\n<div class=\"row\">\n<div class=\"col col-main\">\n<p>PGT-A or preimplantation genetic testing for aneuploidy is the screening of embryos in an assisted reproductive technology cycle for chromosomal abnormalities before they are transferred into the uterus to increase the likelihood of achieving a successful pregnancy.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\">PGT-A was formerly known as PGS, preimplantation genetic screening<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-a-kult.svg\"><img decoding=\"async\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-a-kult.svg\" alt=\"\"\/><\/a><\/figure>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<h2 class=\"wp-block-heading\">PGT-A:<\/h2>\n\n\n\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li class=\" translation-block\"><span class=\"has-color has-nmb-color\"><a rel=\"noreferrer noopener\" href=\"https:\/\/f-genetics.com\/kultivirovanie-embrionov\/\" target=\"_self\">culturing embryos<\/a> for <span class=\"nobr\"> 5-6 days\u00a0<\/span> <em>in vitro<\/em> to the blastocyst stage;<\/span><\/li>\n\n\n\n<li>a biopsy of 5-10 trophectoderm (TE) cells, which form the placenta and other extra-embryonic tissues;<\/li>\n\n\n\n<li>analysis of all chromosomes using a comprehensive chromosome screening approach.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<h4 class=\"is-style-24 wp-block-heading\">Chromosomal abnormalities of the embryo are a potential cause of adverse outcomes of assisted reproductive technology (lack of implantation, failed pregnancy) and congenital malformations.<\/h4>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>20%<\/span>of human eggs<\/span><\/p>\n\n\n<p><span class=\"factoid\"><span>9%<\/span>of human spermatozoa <\/span><\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p>In natural gametogenesis, approximately 20% of human eggs and 9% of human spermatozoa are thought to be aneuploid*. Aneuploid gametes involved in the fertilisation process lead to the development of aneuploid embryos, often resulting in implantation failure or pregnancy loss.<\/p>\n\n\n\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">*Martin RH. Meiotic errors in human oogenesis and spermatogenesis. Reprod BioMed Online 2008;16(4):523-31<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"wp-block-column\">\n<div class=\"row\">\n<div class=\"col col-5\"><\/div>\n\n\n\n<div class=\"col col-5\"><\/div>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>38%\u201376%<\/span>of spontaneous abortions are associated with chromosomal abnormalities <\/span><\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p>According to world and Russian statistics, the prevalence of chromosomal abnormalities detected in spontaneous abortion ranges from 38% to 76%*. The frequency of aneuploidy in embryos in ART cycles increases with maternal age, reaching 80% in patients over 40 years of age**.<\/p>\n\n\n\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">* Chiryaeva O.G. et al., 2012, Volkov A.N. et al. 2017, Carp H, et al., 2001, Rosa Russo et al., 2016)<\/span><br><span class=\"has-color has-mb-400-color\">**Macklon NS et al. Conception to ongoing pregnancy: the \u201cblack box\u201d of early pregnancy loss. Hum Reprod Update 2002;8:333-343<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>38%\u201373%<\/span>of embryos in ART cycles contain aneuploid cells<\/span><\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p>Recent large studies of human embryos have shown that 38-73% of embryos in ART cycles contain aneuploid cells. The differences in the statistics are mainly due to the different average age of the oocytes<\/p>\n\n\n\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">Le Thi Bich Phuong et all. Selecting euploid embryo for transfer by preimplantation genetic testing for aneuploidy improved clinical outcomes in patients with advanced maternal age DOI : 10.15419\/bmrat.v6i12.581<br>X Vi\u00f1als Gonzalez et all, Euploid Blastocysts Implant Irrespective of Their Morphology After NGS-(PGT-A) Testing in Advanced Maternal Age Patients, 2019.<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-2\">\n<p>PGT-A is becoming one of the most valuable tools for increasing the success of assisted reproductive technology pregnancies. As indicators of mosaicism can be quantified by NGS, mosaic embryos on non-viable chromosomes can be considered for transfer when euploid embryos are not available. <\/p>\n\n\n\n<div style=\"height:58px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<h2 class=\"is-style-24 wp-block-heading\">PGT-A has been shown to be associated with:<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<p class=\"has-20-font-size\">Increasing the frequency of implantation<\/p>\n\n\n\n<p>Up to an average of 50-69%, data varies according to age group and associated clinical findings<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">Simon AL, et al, Pregnancy outcomes from more than 1,800 in&nbsp;vitro fertilization cycles with the use of 24-chromosome single-nucleotide polymorphism-based preimplantation genetic testing for aneuploidy. Fertil Steril. 2018<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<p class=\"has-20-font-size\">Reducing the rate of non-developing pregnancies<\/p>\n\n\n\n<p>In the general population, 25% of all clinical pregnancies end in miscarriage. About 50% of sporadic early miscarriages are due to chromosomal defects. The risk of miscarriage decreases when an euploid embryo is transferred.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">Early miscarriage: diagnosis and management, clinical guidelines.<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<p class=\"has-20-font-size\">Reducing the time to gestation<\/p>\n\n\n\n<p>The time to gestation with PGT-A is reduced from 15 weeks to 8 weeks.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">Rubio et al., In vitro fertilization with preimplantation genetic diagnosis for aneuploidies in advanced maternal age: a randomized, controlled study. Fertil Steril. 2017<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<p class=\"has-20-font-size\">Reducing the risk of complications in multiple pregnancies<\/p>\n\n\n\n<p class=\" translation-block\">The high rate of multiple pregnancies is a consequence of multiple embryo transfer in ART programmes. Multiple pregnancies can also occur as a consequence of a naturally occurring pregnancy. According to the 2015 RAHR ART Registry, the rate of multiple pregnancies in the IVF and ICSI programmes was 19.7% of all births, 15.2% following an unfrozen embryo transfer, 20.4% in the Oocyte Donation programme and 25.2% in the surrogacy programme (91).<br>\nSelective transfer of 1 embryo into the uterine cavity is recommended to prevent multiple pregnancies.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">ART and artificial insemination, clinical guidelines<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<p class=\"is-style-blue has-20-font-size\">After the vitrification period, euploid embryos are transferred, allowing time for screening for chromosomal abnormalities and preparing the endometrium for implantation.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-3\">\n<h2 class=\"wp-block-heading\">Indications<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>Late reproductive age for women - 35 years and older<\/li>\n\n\n\n<li>Convulsive miscarriage (2 or more spontaneous abortions in the past)<\/li>\n\n\n\n<li>Repeated implantation failure (3 failed transfers in women under 35 years old and 2 in women of 35 and older)<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>Severe spermatogenesis disorders in men (oligoasthenozoospermia, oligozoospermia, azoospermia)<\/li>\n\n\n\n<li>Carrying balanced chromosomal rearrangements (Robertsonian translocation, certain reciprocal translocations and inversions as well as other numerical and structural chromosomal anomalies).<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<p class=\"is-style-yellow\">In all of these patient groups, an increased incidence of chromosomal abnormalities in embryos is suspected.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-4\">\n<h2 class=\"wp-block-heading\">What PGT-A detects<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li class=\"has-14-font-size\">Aneuploidy<\/li>\n\n\n\n<li class=\"has-14-font-size\">Partial (segmental) aneuploidy<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li class=\"has-14-font-size\">Certain types of polyploidy<\/li>\n\n\n\n<li class=\"has-14-font-size\"><a href=\"https:\/\/f-genetics.com\/en\/mozaiczizm\/\" target=\"_blank\" rel=\"noreferrer noopener\"><span class=\"has-color has-ms-800-color\">Mosaicism<\/span><\/a><\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li class=\"has-14-font-size\">Unbalanced translocations<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<p class=\"has-20-font-size\">Mosaicism can exist in cells that are part of the trophectoderm. The ability to identify mosaicism within the trophectoderm posed a significant challenge and the following approaches have been implemented to overcome this problem:<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>to biopsy at least 5-10 cells. However, the decision on how aggressive the biopsy should be made on a case-by-case basis and weighed against the potential trauma to the embryonic trophectoderm<\/li>\n\n\n\n<li>to use a testing technology capable of identifying mosaicism accurately and with the greatest sensitivity<\/li>\n\n\n\n<li>use validated ploidy (chromosome copy number) thresholds when interpreting data, which can potentially identify an embryo test result as mosaic<\/li>\n<\/ol>\n\n\n\n<p><\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\"><\/div>\n<\/div>\n\n\n\n<p class=\"is-style-blue has-20-font-size\">Current diagnostic technology tests cells intended to become placenta, not cells of the intracellular mass that differentiates into the foetus. Biopsy of the intracellular mass is not recommended because of concerns about further fetal differentiation.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-5\">\n<h2 class=\"wp-block-heading\">How to assess the effectiveness of PGT-A?<\/h2>\n\n\n\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>Implantation index with and without the use of PGT-A overall and in different age groups<\/li>\n\n\n\n<li>Percentage of aneuploid embryos in different age groups<\/li>\n\n\n\n<li>Percentage of mosaicism<\/li>\n<\/ul>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Distribution of samples according to age categories<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"273\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2021\/11\/raspredelnie-obrazczov-v-zavisimosti-ot-vozrastnyh-kategorij-1-eng.png\" alt=\"\" class=\"wp-image-2187\"\/><\/figure>\n<\/div>\n\n\n\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>~8000<\/span>samples<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">First Genetics. PGT-A statistics in age groups<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\">\n<p class=\"has-14-font-size\">% of the norm<\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"559\" height=\"279\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2021\/11\/first-genetics-pgt-a-statistika-v-vozrastnyh-gruppah-normy-1-eng.png\" alt=\"\" class=\"wp-image-1835\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\">\n<p class=\"has-14-font-size\">Recommended for transfer (N+mos)<\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"296\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2021\/11\/first-genetics-pgt-a-statistika-v-vozrastnyh-gruppah-rekomendovannye-k-perenosu-nmos-1-eng.png\" alt=\"\" class=\"wp-image-1837\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\">\n<p class=\"has-14-font-size\">Isolated segmental anomalies (%)<\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"560\" height=\"292\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2021\/11\/first-genetics-pgt-a-statistika-v-vozrastnyh-gruppah-izolirovannye-segmentarnye-narusheniya-1eng.png\" alt=\"\" class=\"wp-image-1838\"\/><\/figure>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">The effectiveness of PGT-A depends largely on the embryological stage of the study!<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"672\" height=\"409\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2021\/06\/frame-4.svg\" alt=\"\" class=\"wp-image-4036\"\/><\/figure>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<p>The table shows the results of \"overachievers\" clinics in Russia with whom we have an established cooperation and no doubts about the \"correctness\" of their \"embryological\" protocol. \"Underachievers\" are single clinics where deviations from the usual statistics were observed and solutions were proposed to audit and search for potential causes of the violations.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p><\/p>\n\n\n\n<p><\/p>\n\n\n\n<h2 class=\"wp-block-heading\">What can affect the success of the outcome?<\/h2>\n\n\n\n<p>Based on data from the transfer of more than 700 euploid embryos, it has been shown that negative predictors of outcome can be:<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-3\">\n<p class=\"is-style-gray has-12-font-size\">the number of pregnancy failures<\/p>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<p class=\"is-style-gray has-12-font-size\">embryo biopsy on day 6 (compared to day 5)<\/p>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<p class=\"is-style-gray has-12-font-size\">elevated BMI<\/p>\n<\/div>\n<\/div>\n\n\n\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">Fazilet Kubra Boynukalin et al.,Parameters impacting the live birth rate per transfer after frozen single euploid&nbsp;blastocyst&nbsp;transfer,&nbsp;2020<\/span><\/p>\n<\/div>\n<\/div><\/div>\n<\/div><\/section><\/div>\t<div class=\"test__aside\">\n\t\t<div class=\"test__links\" id=\"docs\"> \n\t\t\t\t\t\t\t<div><a class=\"doc-link\" href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/09\/pgt-a-metodom-ngs-\u2014-ot-chego-zavisit-razreshenie-metoda_.pdf\" target=\"_blank\"><img decoding=\"async\" src=\"https:\/\/f-genetics.com\/wp-content\/themes\/genetics\/img\/icons\/pdf_purple.svg\" alt=\"\"><span>PGT-A with the NGS method. What does the authorization of the method depend on? (ru) <i>9 MB, PDF<\/i><\/span><\/a><\/div>\n\t\t\t\t\t\t\t<div><a class=\"doc-link\" href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/09\/prezentacziya_mtdnk_rarch.pdf\" target=\"_blank\"><img decoding=\"async\" src=\"https:\/\/f-genetics.com\/wp-content\/themes\/genetics\/img\/icons\/pdf_purple.svg\" alt=\"\"><span>Possibility of using the level of mtDNA in trophectoderm samples as an additional criterion for predicting the outcome of embryo transfer after OGT-A (ru)  <i>2 MB, PDF<\/i><\/span><\/a><\/div>\n\t\t\t\n\t\t\t\t\t\t\t\t\t\t<div> \n\t\t\t\t\t<button class=\"btn purple open-popup-link\" data-mfp-src=\"#ask-question-popup\">Ask a question<\/button>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-row-with-tabs test__row\" id=\"pgt-osobennosti-metoda\"><div class=\"test__col\"><section class=\"test__tabs\"><h2>Features<\/h2><div class=\"inner\">\n<div class=\"wp-block-genetics-tabs c-tabs\"><div class=\"c-tabs__nav\"><div class=\"tabs-wrapper swiper-wrapper\"><div data-tab=\"1\" class=\"tab-link swiper-slide current\" tabindex=\"0\">Biopsy<\/div><div data-tab=\"2\" class=\"tab-link swiper-slide\" tabindex=\"0\">Platform comparison<\/div><div data-tab=\"3\" class=\"tab-link swiper-slide\" tabindex=\"0\">PCR<\/div><div data-tab=\"4\" class=\"tab-link swiper-slide\" tabindex=\"0\">Microarrays<\/div><div data-tab=\"5\" class=\"tab-link swiper-slide\" tabindex=\"0\">NGS in PGT<\/div><\/div><\/div><div class=\"tabs-arrow arrow-prev\">\u2190<\/div><div class=\"tabs-arrow arrow-next\">\u2192<\/div><div class=\"c-tabs__contents\">\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-1 current\">\n<h2 class=\"wp-block-heading\">Embryological aspects of pre-implantation genetic testing<\/h2>\n\n\n\n<p>A biopsy can potentially be performed at three different stages:<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>polar bodies (PB) during fertilisation of the egg,<\/li>\n\n\n\n<li>one or two blastomeres of a cleavage stage embryo (implied by the abbreviation PGS 1.0.)<\/li>\n\n\n\n<li>trophoectoderm at the blastocyst stage (PGS 2.0., and since the PGS 3.0. mosaic embryo detection concept, PGDIS, 2016)<\/li>\n<\/ol>\n\n\n\n<p>Additionally, there are reports in the literature of attempts to aspirate a small volume of blastocoietic fluid.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"is-style-default has-12-font-size\"><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\">All types of the previously mentioned biomaterial can potentially be analysed using different technologies. However:<\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>Blastocyst biopsy is less traumatic than blastocyst biopsy at the cleavage stage, as a smaller proportion of the total cell mass is sacrificed<\/li>\n\n\n\n<li>Polar body biopsy proved to be technically too difficult to perform in routine practice<\/li>\n\n\n\n<li>Polar body biopsy can only detect aneuploidy arising during meiosis<\/li>\n\n\n\n<li>The blastomere biopsy may give a high percentage of false results due to the potential presence of several clones of embryonic cells (mosaicism) at this stage<\/li>\n\n\n\n<li>Vitrification of embryos at the blastocyst stage allows time for embryo research as well as the preparation of the endometrium for euploid embryo transfer.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-2\">\n<h2 class=\"wp-block-heading\">Possible methods for embryo chromosome status screening<\/h2>\n\n\n\n<p>Chromosome analysis has been used in clinical practice since the mid-1990s.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>FISH<\/span> FISH fluorescent hybridisation<\/span><\/p>\n\n\n\n<p>1990s<\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p class=\" translation-block\">Initially, this diagnostic strategy was performed using fluorescent in situ hybridisation (FISH), which consisted <strong>of plating a single embryo cell at the cleavage stage (blastomer) on a slide and hybridising its DNA<\/strong> with chromosome-specific fluorescent probes. The limited number of chromosomal probes examined also meant that some aneuploidies remained untested, leading to the transfer of undetected aneuploid embryos.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p>In the mid-2000s, it became clear that these shortcomings and diagnostic unreliability, combined with the negative consequences of biopsy at the cleavage stage, jeopardised the clinical outcomes of patients for whom PGT-A had been performed, prompting the need for a safer, more reliable and more accurate strategy.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-aside\"><p><span class=\"factoid\"><span>CCS methods<\/span> CCS comprehensive chromosome screening<\/span><\/p>\n\n\n<p><span class=\"factoid\"><span>>98%<\/span> the accuracy that all CCS platforms have shown<\/span><\/p>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p class=\" translation-block\">Subsequently, the development of comprehensive chromosomal screening (<strong>CCS<\/strong>) technologies, including comparative genomic hybridisation (<strong>aCGH<\/strong>), single nucleotide polymorphism arrays (<strong>SNP<\/strong> arrays) and quantitative polymerase chain reaction (<strong>qPCR<\/strong>), have provided significant improvements in the clinical application of PGT-A.<\/p>\n\n\n\n<p class=\" translation-block\">When tested on a single cell from fibroblast cell lines with a known karyotype, all  <strong>CCS<\/strong> platforms showed an accuracy above 98% for the detection of complete aneuploidies.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:32px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\" translation-block\">All platforms that can analyse all 23 pairs of chromosomes have <strong>comparable effectiveness in detecting aneuploidy of an entire chromosome<\/strong>, but differ from each other<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li class=\"has-14-font-size\">in their ability to simultaneously identify other structural chromosomal abnormalities: segmental duplications (dups) or deletions (dels)<\/li>\n<\/ol>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>by the ability to identify mosaicism or the number of copies of mitochondrial DNA<\/li>\n<\/ol>\n<\/div>\n<\/div>\n\n\n\n<div style=\"height:30px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"is-style-gray translation-block\"><strong>aCGH<\/strong>, <strong>SNP<\/strong> and massively parallel sequencing (<strong>MPS<\/strong>, <strong>NGS<\/strong>) require a first step of whole genome amplification (<strong>WGA<\/strong>).<\/p>\n\n\n\n<p class=\"is-style-blue translation-block\"><strong>FISH<\/strong> and <strong>qPCR<\/strong> do not require a pre-amplification step.<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"589\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-1024x589.png\" alt=\"\" class=\"wp-image-2181\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-1024x589.png 1024w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-300x173.png 300w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-768x442.png 768w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-1536x884.png 1536w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-blastocyct@2x-2048x1178.png 2048w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<div style=\"height:40px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p class=\"has-20-font-size\">NGS provides greater accuracy in assessing subchromosomal anomalies (e.g. segmental aneuploidies) than previous <strong>CCS methods<\/strong>.<\/p>\n\n\n\n<p>In addition, NGS is used to detect chromosomal <a href=\"https:\/\/f-genetics.com\/en\/mozaiczizm\/\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>mosaicism<\/strong><\/a> (when two karyotypically different cell populations coexist in the same embryo).<br>However, it is important that the detection of low and high levels of mosaicism (e.g. 20 and 80%, respectively) should be interpreted with extreme caution, as it is quite difficult to distinguish biological findings from the technical features of sequencing that particular sample at these values of mosaicism. This point is extremely important, especially for patients with a limited number of embryos.<\/p>\n\n\n\n<div style=\"height:28px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>In addition, some diagnostic platforms can also test for chromosomal aberrations and single gene mutations simultaneously.<\/p>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-3\">\n<h2 class=\"wp-block-heading\">Quantitative or real-time PCR<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"wp-block-column\" style=\"flex-basis:20%\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"864\" height=\"1024\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-pcr-image-864x1024.png\" alt=\"\" class=\"wp-image-1821\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-pcr-image-864x1024.png 864w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-pcr-image-253x300.png 253w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-pcr-image-768x911.png 768w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-spec-pcr-image.png 980w\" sizes=\"(max-width: 864px) 100vw, 864px\" \/><\/figure>\n<\/div>\n\n\n\n<div class=\"col col-main\">\n<p class=\" translation-block\">Quantitative PCR (qPCR) or real-time PCR (PCR-RV) <strong>is a polymerase chain reaction<\/strong> that can identify aneuploidy of an entire chromosome by determining the copy number of each chromosome analysed.<br>This is achieved by comparing three or four locus-specific amplicons along each chromosome with a reference gene localised on the same chromosome.<\/p>\n\n\n\n<p><br>This analysis can identify aneuploidy for all 23 chromosome pairs in a short time (4-12 hours; depending on the number of samples analysed), and due to the labour-intensive nature of the process in the absence of automation, there is a high risk of error due to human error.<\/p>\n\n\n\n<p><br>qPCR cannot identify structural chromosomal aberrations but can identify triploidy.<\/p>\n\n\n\n<p><br>As qPCR does not detect genotype, it cannot identify uniparental dysosomes. A separate experiment plan can be devised to determine the number of mitochondrial copies.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-4\">\n<p>There are two main types of microarray available for genetic testing. These are single nucleotide polymorphism arrays and comparative genomic hybridisation.<\/p>\n\n\n\n<p><br>For both microarray platforms, trophectoderm cells must be lysed and amplified using some type of DNA amplification protocol that ensures that the entire genome is covered. As with any genetic test, the quality of the diagnostic result begins with the quality of the amplified DNA sample.<\/p>\n\n\n\n<p> <\/p>\n\n\n\n<p> <\/p>\n\n\n\n<h2 class=\"wp-block-heading\">SNP microarrays<\/h2>\n\n\n\n<p>SNPs (single nucleotide polymorphisms) are pairs of single nucleotides (A, T, C or G) in genomic DNA that vary widely within a given species. In the context of PGT-A, the SNPs assessed are usually in non-coding parts of the genome.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<p>After WGA, the embryonic DNA is fragmented and hybridised with an SNP microarray, which contains probes for more than 300,000 different SNP sites across the genome.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<p>After hybridisation, a chain lengthening and staining step is performed. A\/T nucleotides at the SNP site are labelled with red fluorochrome, and G\/C nucleotides at the SNP site are labelled with green fluorochrome.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p>By measuring the fluorescence intensity from red to green at each SNP site in the array, it is possible to simultaneously determine the genotype of more than 300,000 SNPs in each sample and compare the results with the reference human genome map.<\/p>\n\n\n\n<p><br>The data arrays can identify whole chromosome aneuploidy and can also identify approximately 250 common structural chromosomal aberrations across the genome.&nbsp;<\/p>\n\n\n\n<p><br>However, there are hundreds of other chromosome structural abnormalities below the resolution of the 300 000 SNP arrays used for PGT-A, which may play an important role in implantation, miscarriage or the birth of a child with a serious genetic syndrome. As genotype information is provided, these SNP arrays have limited ability to identify triploidy, but can identify uniparental dysomy.&nbsp;<br><\/p>\n\n\n\n<p>SNP microarrays can also identify mosaicism if a sufficient number of trophectoderm cells have been analysed. One limitation of SNP microarrays used for PGT-A is the inability of their algorithm to identify the number of copies when the husband and wife are blood relatives.&nbsp;<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-4\"><\/div>\n\n\n\n<div class=\"col col-6\">\n<p><\/p>\n<\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\">\"CGH microarrays\"<\/h2>\n\n\n\n<p>CGH (aCGH) microarrays are less dense than SNP microarrays. The aCGH chips used for PGT-A have approximately 4000 markers (which are run in a double) located throughout the genome.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-6\">\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"931\" height=\"560\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-365.png\" alt=\"\" class=\"wp-image-1634\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-365.png 931w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-365-300x180.png 300w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-365-768x462.png 768w\" sizes=\"(max-width: 931px) 100vw, 931px\" \/><\/figure>\n\n\n\n<p><\/p>\n<\/div>\n\n\n\n<div class=\"col col-4\">\n<p class=\"has-14-font-size\">aCGH is a protocol for identifying the copy number ratios of a clinical sample to a female or male reference genome. The assay can be performed in a shorter time compared to SNPs (in 12-15 hours).<\/p>\n<\/div>\n<\/div>\n\n\n\n<p>This is a significant advantage over the SNP microarray analysis, which takes around 30-40 hours to complete. Genotypes that are identified in SNPs are not detected in this type of analysis, which means that aCGH cannot distinguish karyotype 46, XX from 69,XXX or 46, XY from 69,XXY. In addition, aCGH cannot detect uniparental dysomy. aCGH, which is used for PGT-A in all commercial laboratories, can only identify whole chromosome aneuploidy and is not designed or validated to identify structural chromosomal aberrations. Even if aCGH microarray is validated for mosaic samples, it should be understood that the ability to detect mosaicism in trophectoderm samples is still limited.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-6\">\n<p>According to some reports, the error rate for aCGH is approximately 15-30%*.<br><br><\/p>\n<\/div>\n\n\n\n<div class=\"col col-4\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">*Capalbo A, Treff NR, Cimadomo D, et al. Comparison of array comparative genomic hybridization and quantitative real-time PCR-based aneuploidy screening of blastocyst biopsies. Eur J Hum Genet: EJHG. 2015;23:901\u20136. doi: 10.1038\/ejhg.2014.222<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-6\">\n<p>In other validation studies, when comparing NGS and CGH, the concordance rate is as high as 99%**.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-4\">\n<p class=\"has-12-font-size\"><span class=\"has-color has-mb-400-color\">** data by Paul R. Brezina, on 400 samples<\/span><\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-5\">\n<h2 class=\"wp-block-heading\">Next generation sequencing (NGS) in PGT-A<\/h2>\n\n\n\n<div class=\"row\">\n<div class=\"col col-main\">\n<p>Next Generation Sequencing (NGS) is a technology that requires very \"careful\" DNA amplification to reduce the likelihood of artefacts during the amplification process.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-aside\">\n<p class=\"has-12-font-size\">However, after DNA amplification, in most cases artefacts can be identified and removed by bioinformatics analysis.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p>   <\/p>\n\n\n\n<h4 class=\"wp-block-heading\">Two main platforms are used for PGT-A<\/h4>\n\n\n\n<p class=\" translation-block\">There are currently two main platforms used for PGT-A. These are Illumina's MiSeq and Thermo-Fisher Scientific's S5. S5 is an improved version of its predecessor PGM.<br>After DNA amplification, approximately 50 ng of each DNA sample is enzymatically cleaved into millions of fragments and combined to prepare a library. Library preparation is the process by which all the DNA fragments are 'cross-linked' with an adapter and a unique identifier, the barcode.<br>A well-prepared library creates a representative objective representation of nucleic acids and is crucial for accurate molecular analysis.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<p class=\"has-14-font-size\">After library preparation, either a bridging PCR step is performed. For MiSeq, sequencing takes place by synthesis based on fluorescence detection, which is recorded using an optical camera.<\/p>\n\n\n\n<p class=\"has-14-font-size\"><br>The platform allows up to 24 samples to be analysed simultaneously.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<p class=\"has-14-font-size\">Once the library has been prepared, either the emulsion PCR step is performed. S5 uses an ion-sensitive field effect in which a signal is detected as the hydrogen ion is released, which occurs whenever a nucleotide triphosphate is incorporated by DNA polymerase during sequencing. <\/p>\n\n\n\n<p class=\"has-14-font-size translation-block\">The release of a proton causes a slight shift in pH, which is recorded by a sensitive sensor.<br>\nThe platform is scalable and can analyse 16, 24 or 96 samples simultaneously.<\/p>\n<\/div>\n<\/div>\n\n\n\n<p class=\" translation-block\">Both MiSeq and S5 sequence the whole genome and compare the sequencing data with the reference human genome.<br>\nBoth platforms allow to perform the analysis (from DNA amplification to final report) in 12-16 hours.<br>\nAfter sequence analysis, significant differences arise between MiSeq data analysis and S5 data analysis.<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-1.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1000\" height=\"305\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-1.png\" alt=\"\" class=\"wp-image-1809\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-1.png 1000w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-1-300x92.png 300w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-1-768x234.png 768w\" sizes=\"(max-width: 1000px) 100vw, 1000px\" \/><\/a><\/figure>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-2.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1000\" height=\"192\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-2.png\" alt=\"\" class=\"wp-image-1810\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-2.png 1000w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-2-300x58.png 300w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/pgt-graf-2-768x147.png 768w\" sizes=\"(max-width: 1000px) 100vw, 1000px\" \/><\/a><\/figure>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<p>MiSeq DNA passes the first round of quality assurance indicators, followed by analysis using <strong>BlueFuse software<\/strong>.<\/p>\n\n\n<p><span class=\"factoid\"><span>MiSeq<\/span>from Illumina <\/span><\/p>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<p class=\" translation-block\">Analysis on S5 passes the first round of quality assurance indicators using the <strong>Torrent Browser<\/strong>, followed by detailed analysis using <strong>the Ion Reporter software<\/strong>.<\/p>\n\n\n<p><span class=\"factoid\"><span>S5 \u0438 PGM<\/span> from Thermo-Fisher Scientific<\/span><\/p>\n<\/div>\n<\/div>\n\n\n\n<p>There are differences in the data analysis of the two platforms. The main point to note is that the bioinformatic data analysis algorithm in Ion Reporter is flexible, customisable to different tasks and available for detailed study. Detailed information can be found in the brochure:<\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<h3 class=\"has-20-font-size wp-block-heading\"><a href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/09\/pgt-a-metodom-ngs-\u2014-ot-chego-zavisit-razreshenie-metoda_.pdf\" target=\"_blank\" rel=\"noreferrer noopener\">PGT-A with the NGS method. What does the authorization of the method depend on? (ru)<\/a><\/h3>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<figure class=\"wp-block-image size-large\"><a href=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1.png\"><img loading=\"lazy\" decoding=\"async\" width=\"1572\" height=\"2224\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1.png\" alt=\"\" class=\"wp-image-1789\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1.png 1572w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1-212x300.png 212w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1-724x1024.png 724w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1-768x1087.png 768w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1-1086x1536.png 1086w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/bro-preview-1-1448x2048.png 1448w\" sizes=\"(max-width: 1572px) 100vw, 1572px\" \/><\/a><\/figure>\n<\/div>\n<\/div>\n<\/div>\n<\/div><\/div>\n<\/div><\/section><\/div><\/div>\n\n\n\n<div class=\"wp-block-genetics-row-with-tabs test__row\" id=\"pgt-tech\"><div class=\"test__col\"><section class=\"test__tabs\"><h2>Technical aspects of PGT<\/h2><div class=\"inner\">\n<div class=\"wp-block-genetics-tabs c-tabs\"><div class=\"c-tabs__nav\"><div class=\"tabs-wrapper swiper-wrapper\"><div data-tab=\"1\" class=\"tab-link swiper-slide current\" tabindex=\"0\">Data quality<\/div><div data-tab=\"2\" class=\"tab-link swiper-slide\" tabindex=\"0\">Solutions with NGS<\/div><div data-tab=\"3\" class=\"tab-link swiper-slide\" tabindex=\"0\">Advantages<\/div><div data-tab=\"4\" class=\"tab-link swiper-slide\" tabindex=\"0\">Conclusions<\/div><\/div><\/div><div class=\"tabs-arrow arrow-prev\">\u2190<\/div><div class=\"tabs-arrow arrow-next\">\u2192<\/div><div class=\"c-tabs__contents\">\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-1 current\">\n<h2 class=\"wp-block-heading\">Possible causes of noise in the graphs of the PGT sample data<\/h2>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"360\" src=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-390-1024x360.png\" alt=\"\" class=\"wp-image-1641\" srcset=\"https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-390-1024x360.png 1024w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-390-300x106.png 300w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-390-768x270.png 768w, https:\/\/f-genetics.com\/wp-content\/uploads\/2020\/10\/image-390.png 1524w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n\n\n<div class=\"row\">\n<div class=\"col col-5\">\n<p class=\" translation-block\">1. Poor sample quality and the emergence of amplification artefacts. Poor sample quality (e.g. degraded DNA) and problems in the DNA amplification step result in increased overall noise and peaks.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p>2. The quality of whole genome amplification can be affected by a number of factors:<\/p>\n\n\n\n<ol class=\"wp-block-genetics-list genetics-list has-12-font-size is-style-arrows\">\n<li>suboptimal embryo biopsy,<\/li>\n\n\n\n<li>\"damaged\" DNA,<\/li>\n\n\n\n<li>incomplete cell lysis,<\/li>\n\n\n\n<li>cells undergoing apoptosis,<\/li>\n\n\n\n<li>the presence of PCR inhibitors in the medium,<\/li>\n\n\n\n<li>deviations from biopsy and examination protocols.<\/li>\n<\/ol>\n\n\n\n<p class=\"has-12-font-size\">These factors tend to be more prominent in single-cell biopsy samples than in trophoectoderm biopsy samples, where more source material is available.<\/p>\n<\/div>\n\n\n\n<div class=\"col col-5\">\n<p>3. insufficient reads can also lead to a noisy profile and the assignment of a false number of copies.<\/p>\n\n\n\n<p><\/p>\n\n\n\n<p>4. How time-consuming certain steps in some manufacturers' protocol are (e.g. washing each sample on magnetic particles can lead to over-drying and deterioration of the sample).<\/p>\n\n\n\n<p><br>It is very important when analysing multiple samples that the DNA concentrations of the samples in the pooled library are balanced.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-2\">\n<h2 class=\"wp-block-heading\">Technical problems in NGS and how to solve them<\/h2>\n\n\n\n<p>Amplification causes 'skewing' towards certain fragments \u2014 thus causing the problem of uneven coverage. The solution is:<\/p>\n\n\n\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>better polymerases<\/li>\n\n\n\n<li>reducing the number of PCR cycles<\/li>\n<\/ol>\n\n\n\n<p>Duplicated reads can over-represent the amplification artefact. The solution is:<\/p>\n\n\n\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>reducing the number of PCR cycles<\/li>\n\n\n\n<li>bioinformatic data processing \u2014 filtering<\/li>\n<\/ol>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-3\">\n<h2 class=\"wp-block-heading\">The benefits of PGT-A at First genetics is quality control at every stage of the test:<\/h2>\n\n\n\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li><strong>Pre-analytical<\/strong> <br>Conducting test biopsies, monitoring compliance with transport and storage regimes<\/li>\n\n\n\n<li><strong>Analytical<\/strong><br>\u2014 minimisation of errors through a more user-friendly protocol for merging and cleaning libraries, automation of sample preparation<br><br>\u2014 using software that automatically flags segmental irregularities \u2014 reducing the risk of missing an event<br><br>\u2014 performing the test on a registered test system<\/li>\n\n\n\n<li><strong>Post-analytical<\/strong><br>\u2014 independent interpretation and analysis of data by three specialists, minimising subjective decisions-developing and training a neural network.<br><br>\u2014 in-depth understanding of the data analysis algorithm and the possibility of flexible settings, depending on the quality of each sample and the indications for the PGT (translocation), continuous training with the software company<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"wp-block-genetics-tab tab-content genetics-tab-4\">\n<h3 class=\"wp-block-heading\">PGT-A is a powerful new tool for optimising assisted reproductive technology.<\/h3>\n\n\n\n<div class=\"row\">\n<div class=\"col col-6\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>Over the past decade, the technology for conducting PGT-A has improved dramatically.<\/li>\n\n\n\n<li class=\" translation-block\">Clinical evidence confirms that <strong>PGT-A increases (improves) the outcome of ART<\/strong> for many groups of patients.<\/li>\n\n\n\n<li class=\" translation-block\">Current recommendations support the use of technologies that assess the ploidy status of <strong>all 23 chromosome pairs<\/strong> at the blastocyst stage with a trophectoderm biopsy when performing PGS.<\/li>\n<\/ol>\n<\/div>\n\n\n\n<div class=\"col col-4\">\n<p class=\"has-12-font-size\">When processing the PGT-A results, laboratory technicians take into account the need to detect small segmental abnormalities.<\/p>\n\n\n\n<p class=\"has-12-font-size translation-block\">If <a href=\"https:\/\/f-genetics.com\/mozaiczizm\/\" target=\"_self\" rel=\"noreferrer noopener\">mosaicism<\/a> (for complete chromosomes or segmental abnormalities) is detected, specialists make a clear recommendation as to whether a particular embryo can be considered for transfer with the patient's informed consent.<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"col col-6\">\n<ol class=\"wp-block-genetics-list genetics-list has-16-font-size is-style-arrows\">\n<li>As indicators of mosaicism can be quantified by NGS, mosaic embryos on non-viable chromosomes can be considered for transfer when euploid embryos are not available.<\/li>\n\n\n\n<li class=\" translation-block\">The patient must be informed <a href=\"https:\/\/f-genetics.com\/ogranicheniya-metoda\/\" target=\"_self\" rel=\"noreferrer noopener\">about the limitations of the method<\/a>.<\/li>\n<\/ol>\n<\/div>\n\n\n\n<div class=\"col col-4\">\n<p class=\"has-12-font-size\">In this scenario, patients should consult their doctor about the consequences of such a transfer.<\/p>\n\n\n\n<p class=\"has-12-font-size\"><br>Separate and special attention is required when considering the possibility of non-lethal aneuploidy transfer (along sex chromosomes 47,XXX, 47XXY, 47XYY).<\/p>\n<\/div>\n<\/div>\n\n\n\n<div class=\"row\">\n<div class=\"wp-block-column\"><\/div>\n<\/div>\n<\/div>\n<\/div><\/div>\n<\/div><\/section><\/div><\/div>\n\n\n\n<div class=\"wp-block-genetics-row test__row\" id=\"pgt-lk\"><div class=\"test__col\"><section class=\"test__tabs\"><h2>\u041b\u0438\u0447\u043d\u044b\u0439 \u043a\u0430\u0431\u0438\u043d\u0435\u0442 \u041f\u0413\u0422-\u0410<\/h2><div class=\"inner\"><div class=\"c-tabs\"><div class=\"c-tabs__nav no-tabs\"><\/div><div class=\"c-tabs__contents\"><div class=\"tab-content current\">\n<p><div class=\"embed-container\"><iframe loading=\"lazy\" title=\"\u041b\u0438\u0447\u043d\u044b\u0439 \u043a\u0430\u0431\u0438\u043d\u0435\u0442 \u041f\u0413\u0422-\u0410 \u043e\u0442 First Genetics\" width=\"787\" height=\"443\" src=\"https:\/\/www.youtube.com\/embed\/pf8nnRxvSHw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" allowfullscreen><\/iframe><\/div><\/p>\n\n\n\n<p>\u0421\u043e\u0431\u0441\u0442\u0432\u0435\u043d\u043d\u043e\u0435 IT&nbsp;\u0440\u0435\u0448\u0435\u043d\u0438\u0435 \u00ab\u041b\u0438\u0447\u043d\u044b\u0439 \u043a\u0430\u0431\u0438\u043d\u0435\u0442\u00bb&nbsp;\u2014 \u0435\u0449\u0435 \u043e\u0434\u043d\u043e \u043f\u0440\u0435\u0438\u043c\u0443\u0449\u0435\u0441\u0442\u0432\u043e \u0441\u043e\u0442\u0440\u0443\u0434\u043d\u0438\u0447\u0435\u0441\u0442\u0432\u0430 \u0441&nbsp;First Genetics.<\/p>\n\n\n\n<p>\u0414\u043b\u044f \u0432\u0440\u0430\u0447\u0435\u0439 \u043a\u043b\u0438\u043d\u0438\u043a-\u043f\u0430\u0440\u0442\u043d\u0435\u0440\u043e\u0432 \u043f\u0440\u0435\u0434\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442\u0441\u044f \u0434\u043e\u0441\u0442\u0443\u043f \u0432&nbsp;\u043b\u0438\u0447\u043d\u044b\u0439 \u043a\u0430\u0431\u0438\u043d\u0435\u0442, \u043a\u043e\u0442\u043e\u0440\u044b\u0439 \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u0435\u0442 \u043e\u0442\u0441\u043b\u0435\u0436\u0438\u0432\u0430\u0442\u044c \u043a\u0430\u0436\u0434\u044b\u0439 \u044d\u0442\u0430\u043f \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u043d\u0438\u044f.<\/p>\n\n\n\n<p>\u0420\u0435\u0448\u0435\u043d\u0438\u0435 \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0430\u043d\u043e \u043f\u0440\u0438 \u043f\u043e\u043c\u043e\u0449\u0438: <\/p>\n\n\n\n<div class=\"row\">\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>Golang 1.18<\/li>\n\n\n\n<li>Vue v2<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>PostgreSQL 14<\/li>\n\n\n\n<li>Redis<\/li>\n<\/ul>\n<\/div>\n\n\n\n<div class=\"col col-3\">\n<ul class=\"wp-block-genetics-list genetics-list has-16-font-size\">\n<li>Docker<\/li>\n\n\n\n<li>k3s<\/li>\n<\/ul>\n<\/div>\n<\/div>\n\n\n\n<p>\u041e\u0437\u043d\u0430\u043a\u043e\u043c\u0438\u0442\u0441\u044f \u0441&nbsp;\u0444\u0443\u043d\u043a\u0446\u0438\u043e\u043d\u0430\u043b\u043e\u043c \u0440\u0435\u0448\u0435\u043d\u0438\u044f \u043c\u043e\u0436\u043d\u043e \u0432&nbsp;\u0432\u0438\u0434\u0435\u043e \u0438\u043d\u0441\u0442\u0440\u0443\u043a\u0446\u0438\u0438.<\/p>\n<\/div><\/div><\/div><\/div><\/section><\/div><\/div>","protected":false},"template":"templates\/test-for-specialists.php","class_list":["post-822","test","type-test","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v23.8 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>\u041f\u0413\u0422-\u0410 - First Genetics<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/f-genetics.com\/en\/pgt-2\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" 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