Preimplantation Genetic Diagnosis Research Articles

Politics of reproduction: a view from Israel on the Dobbs decision

BackgroundThis opinion piece looks at the recent decision of the United States Supreme Court in Dobbs v. Jackson Women's Health Organization and then compares the law on abortion in the USA to the law in Israel on reproductive medicine in general.The Dobbs decision validated a Mississippi state law that restricted access to abortion, while overruling the landmark precedent of Roe v. Wade on women's constitutional right to safe abortion. It declared that the US constitution does not confer upon women any right to abortion, whether pre- or post-viability, sending shockwaves throughout the world. It also had an immediate effect on women's reproductive health in the US.Main bodyWomen's right to reproductive freedom and to make decisions about their lives and their bodies is key to their hard-won equality. Still, abortion remains in ongoing controversy worldwide with legal barriers that impact upon the most vulnerable. In Israel, abortion is relatively available, accessible, affordable, and acceptable, in both law and practice. This is because of the lenient and nuanced stance of rabbinical authorities in the Jewish law tradition. This stance, together with Israel's post-Holocaust biblical culture of "be fruitful and multiply", also underlies its high rates of medically assisted reproduction for the treatment of infertility, including preimplantation genetic diagnosis of fertilized eggs. Women's bodies mediate all these repro-genetic technologies, in most cases for the benefit of others, not because of their own health needs. There is also concern about global practices and market forces that objectify women's bodies, exploit women and are harmful to their health, wellbeing, and dignity, carrying on outdated patriarchal patterns.ConclusionReproductive health policy ought to be based on an ethic of care and responsibility first and foremost for the women, as well as the children they choose to bring to life, in the spirit of the Jewish tradition that her life is of greater value than the fetus'. Women deserve control of their bodies and their lives and respect for the choices they make to the best of their judgment, which when it comes to abortion are mostly hard ones. They have a right to reproductive choice, freedom, autonomy, and dignity.The views expressed in this perspective are those of the author.

Identification of a Novel Frameshift Variant of ARR3 Related to X-Linked Female-Limited Early-Onset High Myopia and Study on the Effect of X Chromosome Inactivation on the Myopia Severity.

X-linked myopia 26 (Myopia 26, MIM #301010), which is caused by the variants of ARR3 (MIM *301770), is characterized by female-limited early-onset high myopia (eo-HM). Clinical characteristics include a tigroid appearance in the fundus and a temporal crescent of the optic nerve head. At present, the limited literature on eo-HM caused by ARR3 mutations shows that its inheritance mode is complex, which brings certain difficulties to pre-pregnancy genetic counseling, pre-implantation genetic diagnosis, and prenatal diagnosis. Here, we investigated the genetic underpinning of a Chinese family with eo-HM. Whole exome sequencing of the proband revealed a novel frameshift mutation in ARR3 (NM_004312, exon10, c.666delC, p. Asn222LysfsTer22). Although the mode of inheritance of the eo-HM family fits the X-linked pattern of ARR3, the phenotypes of three patients deviate from the typical early-onset high myopia. Through X-chromosome inactivation experiments, the patient's different phenotypes can be precisely explained. In addition, this study not only enhanced the correlation between ARR3 and early-onset high myopia but also provided explanations for different phenotypes, which may inspire follow-up studies. Our results enrich the knowledge of the variant spectrum in ARR3 and provide critical information for preimplantation and prenatal genetic testing, diagnosis, and counseling.

Obstetric, neonatal, and child health outcomes following embryo biopsy for preimplantation genetic testing.

Preimplantation genetic testing (PGT) of embryos developed in vitro requires a biopsy for obtaining cellular samples for the analysis. Signs of cell injury have been described in association with this procedure. Thus, the consequences of the biopsy on obstetric and neonatal outcomes have been the subject of some quantitative analyses, although the reliability of data pooling may be limited by important issues in the various reports. The present review identifies evidence for whether pregnancies conceived after embryo biopsy are associated with a higher risk of adverse obstetric, neonatal, and long-term outcomes. Available evidence has been summarized considering manipulation at various stages of embryo development. We used the scoping review methodology. Searches of article databases were performed with keywords pertaining to the embryo biopsy technique and obstetric, neonatal, and postnatal outcomes. Studies in which embryos were biopsied at different stages (i.e. both at the cleavage and blastocyst stages) were excluded. We included data on fresh and frozen embryo transfers. The final sample of 31 documents was subjected to qualitative thematic analysis. Sound evidence is lacking to fully address the issues on the potential obstetric, neonatal or long-term consequences of embryo biopsy. For polar body biopsy, the literature is too scant to draw any conclusion. Some data, although limited and controversial, suggest a possible association of embryo biopsy at the cleavage stage with an increased risk of low birthweight and small for gestational age neonates compared to babies derived from non-biopsied embryos. An increase in preterm deliveries and birth defects in cases of trophectoderm biopsy was suggested. For both biopsy methods (at the cleavage and blastocyst stages), an increased risk for hypertensive disorders of pregnancy was found. However, these findings may be explained by confounders such as other embryo manipulation procedures or by intrinsic patient or population characteristics. Since there is inadequate evidence to assess obstetric, neonatal, and long-term health outcomes following embryo biopsy, an invasive PGT strategy should be developed with a cautious approach. A non-invasive approach, based on the analysis of embryo cell-free DNA, needs to be pursued to overcome the potential limitations of embryo biopsy.

Parental experience with an ocular genetic counseling services in Saudi Arabia.

This study reports parental attitudes towards preimplantation genetic diagnosis (PGD) and their satisfaction with genetic counseling services offered by a territory eye care hospital in Saudi Arabia. This was a cross-sectional study of 30 parents (either father or mother) of children affected by recessive genetic ocular disorders. Their basic knowledge of recessive genetic disorders, attitude toward PGD, and satisfaction with counseling services were assessed using structured telephonic interviews. Eighty percent of the participants understood the concept of recessive inheritance patterns and the effect of consanguineous marriages on raising the likelihood of giving birth to a child with genetic disorders. Forty-seven percent of parents understood the risk of having an affected future offspring. Sixty-seven percent of them mentioned that they would consider using preventive measures when conceiving next time. Seventy-three percent of participants stated that they would share the genetic test results with family members. Ninety percent of the parents were satisfied with the genetic counselor's ability to listen to them and the way the counselor explained the genetic information. There was a statistically significant association between parental willingness to share genetic test results with relatives and being given the opportunity to share information with their genetic counselor (P = 0.01). There was no association between the parental's knowledge and their willingness to consider using preventative measures in the next pregnancy. Most parents had a basic understanding of recessive disease. However, they often struggled to comprehend the science and mathematical probabilities determining the recurrence risk in future pregnancies. This complexity makes it difficult for them to recall the information. Attitude toward PGD did not seem to be related with parent knowledge. A significant proportion of the parents expressed willingness to share their genetic test results with relatives, but some were hesitant due to fears of stigma. Most parents were satisfied with genetic counseling services.

Embryo quality and chromosomal abnormality in embryos from couples undergoing assisted reproductive technology using preimplantation genetic screening

Objective: To detect common chromosomal aneuploidy variations in embryos from couples undergoing assisted reproductive technology and preimplantation genetic screening and their possible associations with embryo quality. Methods: In this study, 359 embryos from 62 couples were screened for chromosomes 13, 21, 18, X, and Y by fluorescence insitu hybridization. For biopsy of blastomere, a laser was used to remove a significantly smaller portion of the zona pellucida. One blastomere was gently biopsied by an aspiration pipette through the hole. After biopsy, the embryo was immediately returned to the embryo scope until transfer. Embryo integrity and blastocyst formation were assessed on day 5. Results: Totally, 282 embryos from 62 couples were evaluated. The chromosomes were normal in 199 (70.57%) embryos and abnormal in 83 (29.43%) embryos. There was no significant association between the quality of embryos and numerical chromosomal abnormality (P=0.67). Conclusions: Embryo quality is not significantly correlated with its genetic status. Hence, the quality of embryos determined by morphological parameters is not an appropriate method for choosing embryos without these abnormalities.

Tlön, Uqbar, ChatGPT

This essay is based on a close reading of two poems written by ChatGPT. One is about preimplantation genetic testing; the other is about Down syndrome. Examining these AI-generated poems along with several human-composed texts, the author—the father of a young woman with Down syndrome—explores a number of related topics, including the difference between human- and machine-written poetry; ableist bias in large language models; the future of people with intellectual disabilities, in a world of machine intelligence; and the value of writing by people with disabilities. The author does not reject the use of ChatGPT or preimplantation genetic diagnosis, but argues that for them to be compatible with human flourishing, we need to consider the way they are sold to us, the need for regulation, and the assumptions they embed.

Consanguinity, Fertility and Reproductive Outcomes: An International Review

Consanguineous marriages have been common throughout human history, and remain so even today in many parts of the world. Many Arab countries display some of the highest rates of consanguinity and, specifically, first cousin marriages which may encompass 25 to 30 percent of all marriages. The effects of inbreeding on reproductive outcome have been extensively studied. It used to be generally believed that inbreeding contributed to increased mortality and morbidity with detrimental effects on reproductive outcome; however, some studies have shown only a moderate to slight impact. The fertility of consanguineous couples and infant and childhood morbidity and mortality in their progeny have also been extensively studied and numerous studies have concluded that consanguinity is not associated with either a significant positive or negative effect on fertility. The majority of studies found that first cousin couples produce more children. In many cases the mean number of live births to women in consanguineous marriages has been reported as being higher than that in non-consanguineous unions, although several studies found that mean fertility rates may be lower in consanguineous couples. In general, higher total fertility rates have been reported in consanguineous marriages. Reports regarding the association of consanguinity and fetal wastage are conflicting, with some reporting that the total prenatal losses were essentially the same for consanguineous and non-consanguineous. Congenital malformations have long been established to be higher in consanguineous couples about the background rate (4.5% vs 1%). Due to the principle of the existence of a common ancestor. Consanguinity is most commonly associated with inborn errors of metabolism, most of which are autosomal recessive. Consanguinity also increases the incidence of multi-factorial disorders such as diabetes, cardiovascular disorders, obesity and certain types of cancers, which may in turn affect reproductive outcomes. Pregnancy outcomes, such as increased pregnancy wastage and preterm labor have been reported with consanguineous marriages. The most significant effects on reproductive outcomes are mostly due to autosomal recessive inherited conditions and inborn errors in metabolism. In the future, with completion of the study of the whole human Genome and current advances in pre-implantation diagnosis and screening it may be possible to mitigate some of the adverse reproductive outcomes associated with consanguinity.

Preimplantation genetic testing for aneuploidy and chromosomal structural rearrangement: A summary of a nationwide study by the Japan Society of Obstetrics and Gynecology.

The Japan Society of Obstetrics and Gynecology conducted a nationwide clinical study to evaluate the pregnancy outcomes of preimplantation genetic testing for aneuploidy or chromosomal structural rearrangement (PGT-A/SR). Patients that had experienced recurrent implantation failure, recurrent pregnancy loss, or chromosomal structural rearrangement were recruited from 200 fertility centers in Japan. For patients in whom one or more blastocysts were classified as euploid or euploid with suspected mosaicism, a frozen-thawed single embryo transfer (ET) was performed. A total of 10 602 cycles, maternal age 28-50 years, were enrolled in this study. 42 529 blastocysts were biopsied, and 25.5%, 11.7%, and 61.7% of embryos exhibited euploidy, mosaicism, and aneuploidy, respectively. At least one euploid blastocyst was obtained in 38.3% of egg retrieval cycles with embryo biopsy. A total of 6080 ETs were carried out, and the clinical pregnancy rate per ET, ongoing pregnancy rate per ET, and miscarriage rate per pregnancy were 68.8%, 56.3%, and 10.4%, respectively. The rates of clinical pregnancy and miscarriage remained relatively constant across all maternal ages. Preimplantation genetic testing for aneuploidy or chromosomal structural rearrangement may improve the pregnancy rate per ET and reduce the miscarriage rate per pregnancy, especially in patients of advanced maternal age.

Genomic autopsy to identify underlying causes of pregnancy loss and perinatal death

Pregnancy loss and perinatal death are devastating events for families. We assessed ‘genomic autopsy’ as an adjunct to standard autopsy for 200 families who had experienced fetal or newborn death, providing a definitive or candidate genetic diagnosis in 105 families. Our cohort provides evidence of severe atypical in utero presentations of known genetic disorders and identifies novel phenotypes and disease genes. Inheritance of 42% of definitive diagnoses were either autosomal recessive (30.8%), X-linked recessive (3.8%) or autosomal dominant (excluding de novos, 7.7%), with risk of recurrence in future pregnancies. We report that at least ten families (5%) used their diagnosis for preimplantation (5) or prenatal diagnosis (5) of 12 pregnancies. We emphasize the clinical importance of genomic investigations of pregnancy loss and perinatal death, with short turnaround times for diagnostic reporting and followed by systematic research follow-up investigations. This approach has the potential to enable accurate counseling for future pregnancies.

The embryo non-invasive pre-implantation diagnosis era: how far are we?

Advancements in assisted reproduction (AR) methodologies have allowed significant improvements in live birth rates of women who otherwise would not be able to conceive. One of the tools that allowed this improvement is the possibility of embryo selection based on genetic status, performed via preimplantation genetic testing (PGT). Even though the widespread use of PGT from TE biopsy helped to decrease the interval from the beginning of the AR intervention to pregnancy, especially in older patients, in AR, there are still many concerns about the application of this invasive methodology in all cycles. Therefore, recently, researchers started to study the use of cell free DNA (cfDNA) released by the blastocyst in its culture medium to perform PGT, in a method called non-invasive PGT (niPGT). The development of a niPGT would bring the diagnostics power of conventional PGT, but with the advantage of being potentially less harmful to the embryo. Its implementation in clinical practice, however, is under heavy discussion since there are many unknowns about the technique, such as the origin of the cfDNA or if this genetic material is a true representative of the actual ploidy status of the embryo. Available data indicates that there is high correspondence between results observed in TE biopsies and the ones observed from cfDNA, but these results are still contradictory and highly debatable. In the present review, the advantages and disadvantages of niPGT are presented and discussed in relation to tradition TE biopsy-based PGT. Furthermore, there are also presented some other possible non-invasive tools that could be applied in the selection of the best embryo, such as quantification of other molecules as quality biomarkers, or the use artificial intelligence (AI) to identify the best embryos based on morphological and/or morphokitetic parameters.

Production of light-coloured, low heat-absorbing Holstein Friesian cattle by precise embryo-mediated genome editing

Context Genome editing enables the introduction of beneficial sequence variants into the genomes of animals with high genetic merit in a single generation. This can be achieved by introducing variants into primary cells followed by producing a live animal from these cells by somatic cell nuclear transfer cloning. The latter step is associated with low efficiencies and developmental problems due to incorrect reprogramming of the donor cells, causing animal welfare concerns. Direct editing of fertilised one-cell embryos could circumvent this issue and might better integrate with genetic improvement strategies implemented by the industry. Methods In vitro fertilised zygotes were injected with TALEN editors and repair template to introduce a known coat colour dilution mutation in the PMEL gene. Embryo biopsies of injected embryos were screened by polymerase chain reaction and sequencing for intended biallelic edits before transferring verified embryos into recipients for development to term. Calves were genotyped and their coats scanned with visible and hyperspectral cameras to assess thermal energy absorption. Key results Multiple non-mosaic calves with precision edited genotypes were produced, including calves from high genetic merit parents. Compared to controls, the edited calves showed a strong coat colour dilution which was associated with lower thermal energy absorbance. Conclusions Although biopsy screening was not absolutely accurate, non-mosaic, precisely edited calves can be readily produced by embryo-mediated editing. The lighter coat colouring caused by the PMEL mutation can lower radiative heat gain which might help to reduce heat stress. Implications The study validates putative causative sequence variants to rapidly adapt grazing cattle to changing environmental conditions.

The effect of trophectoderm biopsy for preimplantation genetic testing on fetal birth weight and preterm delivery.

Preimplantation genetic testing for aneuploidy (PGT-A) is used as part of in-vitro-fertilization (IVF) to assist in selection of euploid embryos, which involves performing trophectoderm biopsy. The effect of possible trauma caused by biopsy and the implication on pregnancy is unknown. Hence, the objective of the study was to determine if embryo biopsy for PGT-A affects birth weight or preterm birth rate. Using National Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) data, we identified 6352 cycles which had single embryo transfer (SET) and a singleton live birth following frozen embryo transfer (FET) between 2014 and 2015. From the initial cohort of 25,121 fresh stimulation cycles, 6352 cycles were included who had a singleton live birth following FET. A total of 3482 (54.8%) had PGT-A confirmed euploid embryos and 2870 (45.2%) had embryos selected based on morphology for transfer. No difference in birthweight (g) was noted when FET was performed using PGT-A confirmed euploid embryos as compared to non-tested morphologically selected embryos (3370.7 vs. 3354.5, adjusted regression coefficient 11.4; 95% CI: -12.6; 35.3). As compared to morphologically selected embryos, performance of PGT-A did not increase the risk of small for gestation age (SGA) (3.9% vs. 4.1%, OR: 1.13; 95% CI: 0.86-1.50), low birth weight (LBW) (<2500 g but ≥1500 g) (5.8% vs. 5.5%, OR: 0.90; 95% CI: 0.66-1.21), or very low birthweight (<1500 g) (1.3% vs. 1.0%, OR: 0.44; 95% CI: 0.44 (0.18-1.10). There was no increased risk of preterm birth (PTB) associated with pregnancy resulting from PGT-A embryos vs. non PGT-A embryos (15.8% vs. 16.4%, OR: 0.94; 95% CI: 0.81-1.09). In our study, trophectoderm biopsy for PGT-A did not increase the risk of SGA, LBW or PTB in IVF pregnancies.

Embryo biopsies for genomic selection in tropical dairy cattle.

Genomic selection has transformed the livestock industry, enabling early-life selection of animals. Biopsy sampling of pre-implantation embryos has been described since 1968. However, it was only after 2010, with the advancement of molecular biology techniques such as whole genomic amplification and SNP Chips, that next-generation sequencing became commercially available for bovine embryos. It is now possible to make decisions about which embryos to transfer not only based on recipients' availability or embryo morphology but also on genomic estimates. This technology can be implemented for a wide spectrum of applications in livestock. In this review, we discuss the use of embryo biopsy for genomic selection and share our experience with Gir and Girolando Brazilian breeding programs, as well as future goals for implementing it in Brazilian bovine in vitro embryo production practices.

Legal Regulation of Preimplantation Genetic Diagnosis: A Comparative Analysis of the Baltic Sea Region and the Nordic Countries

This paper examines the concept and regulation of some of the latest research in the field of fertility – preimplantation genetic diagnosis – in Lithuania, Poland, the Baltic States, and the Nordic countries. Preimplantation genetic diagnosis raises many legal and ethical questions regarding the protection of embryos, manipulation of the human genome, selection by sex, and the relation of this diagnosis to other similar studies. International legislation or guidelines define genetic testing, including pre-implantation genetic diagnosis, quite broadly, due to the scope of regulation and nuances, leaving the right to decide to the discretion of each state. National regulation of preimplantation genetic diagnosis should be specific, clearly defining cases in which preimplantation genetic diagnosis is applied.

BHLHA9 homozygous duplication in a consanguineous family: A challenge for genetic counseling.

Split-hand/foot malformation (SHFM) with long-bone deficiency (SHFLD) is a rare condition characterized by SHFM associated with long-bone malformation usually involving the tibia. It includes three different types; SHFLD1 (MIM % 119,100), SHFLD2 (MIM % 610,685) and SHFLD3 (MIM # 612576). The latter was shown to be the most commonly reported with a duplication in the 17p13.1p13.3 locus that was narrowed down to the BHLHA9 gene. Here, we report a consanguineous Lebanese family with three members presenting with limb abnormalities including tibial hemimelia. One of these patients presented with additional bowing fibula and another with bilateral split hand. CGH array analysis followed by RQ-PCR allowed us to detect the first homozygous duplication on the short arm of chromosome 17p13.3 including the BHLHA9 gene and involved in SHFLD3. Interestingly, one patient with the homozygous duplicated region, carrying thus four BHLHA9 copies presented with long bone deficiency but no SHFM. The incomplete penetrance and the variable expressivity of the disease in this family as well as the presence of the BHLHA9 homozygous duplication rendered genetic counseling extremely challenging and preimplantation genetic diagnosis almost impossible.

Prenatal diagnosis and preimplantation genetic diagnosis for sickle cell disease in Africa

Sickle cell disease (SCD) is the most common genetic haematological disorder worldwide, and it is a major public health concern, especially in Sub-Saharan Africa. Prenatal diagnosis (PD) and preimplantation genetic diagnosis (PGD) are important reproductive options for the prevention of SCD. Despite the high prevalence of SCD in Nigeria and Sub-Saharan Africa, current trends in PD and PGD for the prevention of SCD are still slow compared to that in developed countries. Attitudes towards PD and PGD for the prevention of SCD in African are influenced by level of awareness, knowledge and educational status, and the main barriers to the uptake of PD and PGD for SCD in Africa are cost, religion, sociocultural, ethical and moral considerations. We reviewed available data on PD and PGD for SCD in Africa, using the PubMed, PubMed Central, Google Scholar and African Index Medicus search engines, through a combination of words and phrases relevant to the subject. This article reviewed the current trends in PD and PGD for the prevention of SCD and discussed the attitudes towards and the barriers to the uptake of PD and PGD for SCD in Africa.

First report of preimplantation genetic diagnosis of mucopolysaccharidoses IVA and HLA typing for hematopoietic stem cell transplantation

BackgroundMucopolysaccharidoses IVA is an autosomal recessive lysosomal storage disease resulting in skeletal and cartilage dysplasia. Hematopoietic stem cell transplantation is a good therapeutic option for MPS IV. Here we report the first application of PGD test for MPS IVA and HLA with the purpose of HSCT for the affected son in a family with consanguineous marriage. Haplotype analysis of linked STR markers in GALNS gene and HLA loci as well as variant detection by cycle sequencing were included in our PGD test.ResultsTwo out of nine embryos were transferrable. The second embryo transfer was successful and resulted in the pregnancy of one healthy and HLA matched girl.ConclusionsPreimplantation genetic diagnosis could be considered as a noninvasive clinical option for families with a mucopolysaccharidoses IVA patient to have a healthy child that is HLA-matched with the patient in need of hematopoietic stem cell transplantation. In lack of an appropriate hematopoietic stem cell donor the importance of preimplantation genetic diagnosis is much more significant too.

Feminist Surveillance Studies and the Institutionalization of Interphobia

Though sex, gender, and sexuality have been subject to ongoing forms of state scrutiny and, therefore, concern surveillance studies scholars—one can think of McCarthy and the policing of homosexuality and the current forms of homophobia and cisgenderism structuring bathroom, sport, and “Don’t Say Gay” laws in the US—there is a glaring lack of attention paid to the violent (colonial) state, legal, and medical projects that surveil intersex people’s body-minds with the (eugenic) goal of eradicating intersex variations to make sex, gender, and sexuality “legible,” dyadic. There is a lack of attention paid to intersex issues in mainstream media as well as from surveillance studies scholars. As a result, as scholars reflect backward over the decades of scholarship in surveillance studies in this anniversary issue of Surveillance &amp; Society, we posit that it is time to use the refined tools surveillance studies offers in service of opposing the often-ignored ongoing surveillance—and killing project—of intersex people’s unique sex traits. In doing so, we focus our attention on surgical interventions, medical photography, and the reproductive technology preimplantation genetic diagnosis. These three case studies offer a sampling of the various ways intersex variations are surveilled and eradicated, and, therefore, signal the importance of integrating intersex issues into feminist surveillance studies. To conclude, we address how intersex activists find each other and propel their activism—activism that combats the surveiling and regulating nature of state and medical-sanctioned interphobia—into the mainstream via information and communication technologies. And yet, there remains so much work to be done. We end on the cautionary note that the ways that intersex activists’ work is routinely stymied and undermined by state and medical forces must be considered.

Identification of Important Factors Causing Developmental Arrest in Cloned Pig Embryos by Embryo Biopsy Combined with Microproteomics.

The technique of pig cloning holds great promise for the livestock industry, life science, and biomedicine. However, the prenatal death rate of cloned pig embryos is extremely high, resulting in a very low cloning efficiency. This limits the development and application of pig cloning. In this study, we utilized embryo biopsy combined with microproteomics to identify potential factors causing the developmental arrest in cloned pig embryos. We verified the roles of two potential regulators, PDCD6 and PLK1, in cloned pig embryo development. We found that siRNA-mediated knockdown of PDCD6 reduced mRNA and protein expression levels of the pro-apoptotic gene, CASP3, in cloned pig embryos. PDCD6 knockdown also increased the cleavage rate and blastocyst rate of cloned porcine embryos. Overexpression of PLK1 via mRNA microinjection also improved the cleavage rate of cloned pig embryos. This study provided a new strategy to identify key factors responsible for the developmental defects in cloned pig embryos. It also helped establish new methods to improve pig cloning efficiency, specifically by correcting the expression pattern of PDCD6 and PLK1 in cloned pig embryos.

Fetal akinesia deformation sequence syndrome associated with recessive TTN variants.

Arthrogryposis multiplex congenita (AMC) [also known as multiple joints contracture or Fetal Akinesia Deformation Sequence (FADS)] is etiologically a heterogeneous condition with an estimated incidence of approximately 1 in 3000 live births and much higher incidence when prenatally diagnosed cases are included. The condition can be acquired or secondary to fetal exposures and can also be caused by a variety of single-gene disorders affecting the brain, spinal cord, peripheral nerves, neuromuscular junction, muscle, and a variety of disorders affecting the connective tissues (Niles et al., Prenatal Diagnosis, 2019; 39:720-731). The introduction of next-generation gene sequencing uncovered many genes and causative variants of AMC but also identified genes that cause both dominant and recessive inherited conditions with the variability of clinical manifestations depending on the genes and variants. Molecular diagnosis in these cases is not only important for prognostication but also for the determination of recurrence risk and for providing reproductive options including preimplantation and prenatal diagnosis. TTN, the largest known gene in the human genome, has been known to be associated with autosomal dominant dilated cardiomyopathy. However, homozygote and compound heterozygote pathogenic variants with recessive inheritance have rarely been reported. We report the effect of recessive variants located within the fetal IC and/or N2BA isoforms in association with severe FADS in three families. All parents were healthy obligate carriers and none of them had cardiac or skeletal muscle abnormalities. This report solidifies FADS as an alternative phenotypic presentation associated with homozygote/compound heterozygous pathogenic variants in the TTN.