Clinical outcomes following preimplantation genetic testing for monogenic conditions, a systematic review of observational studies.

OBJECTIVE: We aimed to report a summary of clinical outcomes following preimplantation genetic testing for monogenic conditions, by performing a systematic review of published literature on clinical pregnancy and live birth rates following preimplantation genetic testing due to a monogenic indication. Additionally, we aimed to undertake a subgroup analysis of clinical outcomes of concurrent monogenic and aneuploidy screening. DATA SOURCES (INCLUDING YEARS SEARCHED): Three electronic databases (MEDLINE, EMBASE and PubMed) were searched from inception to May 2024. STUDY ELIGIBILITY CRITERIA (STUDY DESIGN, POPULATIONS, AND INTERVENTIONS [IF APPLICABLE]): Quantitative data audits, observational studies and case series reporting clinical outcomes for individuals undergoing preimplantation genetic testing for a monogenic indication were included. Only studies using blastocyst biopsies with polymerase chain reaction-based or genome-wide haplotyping methods for molecular analysis were eligible to reflect current laboratory practice. STUDY APPRAISAL AND SYNTHESIS METHODS: Quality assessment was performed following data extraction using an adaptation of the Joanna Briggs critical appraisal tool for case series. Results were extracted, and pooled mean clinical pregnancy rates and birth rates were calculated with 95% confidence intervals. We compared outcomes between those with and without concurrent PGT-A. RESULTS: Our search identified 1372 publications; 51 were eligible for inclusion. Pooled data on 5305 cycles and 5229 embryo transfers yielded 1806 clinical pregnancies and 1577 births. This translated to clinical pregnancy and birth rates of 34.0% [95%CI: 32.8-35.3%] and 29.7% [95%CI: 28.5-31.0%] per cycle and 24.8% [95%CI: 23.6-26.0%] and 21.7% [95%CI: 20.8-23.1%] per embryo transfer. In studies with concurrent aneuploidy screening, clinical pregnancy and birth rates were 43.3% [95%CI: 40.2-46.5%] and 37.6% [95%CI: 34.6-40.8%] per cycle and 37.0% [95%CI: 33.9-40.3%] and 31.8% [95%CI: 28.8-35.0%] per embryo transfer. Studies without aneuploidy screening reported clinical pregnancy and birth rates of 32.5% [95%CI: 31.0-34.1%] and 28.1% [95%CI: 26.6-29.7%] per cycle and 21.2% [95%CI: 19.8-22.6%] and 18.6% [95%CI: 17.3-20.0%] per embryo transfer. CONCLUSIONS: This systematic review reveals promising clinical outcome figures for this indication group. Additionally, synthesizing the published scientific literature on clinical outcomes from preimplantation genetic testing for monogenic conditions provides a rigorous, non-commercial evidence base for counselling.

The preimplantation genetic testing for monogenic disorders strategy for blocking the transmission of hereditary cancers through haplotype linkage analysis by karyomapping.

PURPOSE: Providing feasible preimplantation genetic testing strategies for monogenic disorders (PGT-M) for prevention and control of genetic cancers. METHODS: Inclusion of families with a specific pathogenic mutation or a clear family history of genetic cancers. Identification of the distribution of hereditary cancer-related mutations in families through genetic testing. After a series of assisted reproductive measures such as down-regulation, stimulation, egg retrieval, and in vitro fertilization, a biopsy of trophectoderm cells from a blastocyst was performed for single-cell level whole-genome amplification (WGA). Then, the detection of chromosomal aneuploidies was performed by karyomapping. Construction of a haplotype-based linkage analysis to determine whether the embryo carries the mutation. Meanwhile, we performed CNV testing. Finally, embryos can be selected for transfer, and the results will be verified in 18-22 weeks after pregnancy. RESULTS: Six couples with a total of 7 cycles were included in our study. Except for cycle 1 of case 5 which did not result in a transferable embryo, the remaining 6 cycles produced transferable embryos and had a successful pregnancy. Four couples have had amniotic fluid tests to confirm that the fetus does not carry the mutation, while 1 couple was not tested due to insufficient pregnancy weeks. And the remaining couples had to induce labor due to fetal megacystis during pregnancy. CONCLUSION: Our strategy has been proven to be feasible. It can effectively prevent transmission of hereditary cancer-related mutations to offspring during the prenatal stage.

Identification of carrier status of Xp22.31 microdeletions associated with X-linked ichthyosis at the single-cell level using haplotype linkage analysis by karyomapping.

PURPOSE: Currently, owing to the limitations of high-throughput sequencing depth and the allele dropout caused by the whole-genome amplification, detection of chromosomal variants in embryos with CNVs <5 Mb is unsatisfactory at the single-cell level using only conventional sequencing methods. Therefore, here we aimed to use a strategy of preimplantation genetic testing for monogenic (PGT-M) to compensate for the shortcomings of conventional sequencing methods. The purpose of this study is to report the effectiveness of haplotype linkage analysis by karyomapping for preimplantation diagnosis microdeletion diseases. METHODS: Six couples carrying chromosomal microdeletions associated with X-linked ichthyosis were recruited, and all couples entered the PGT process. Multiple displacement amplification (MDA) method was used to amplify the whole-genome DNA of trophectoderm cells. Then karyomapping based on single nucleotide polymorphism (SNP) was used for haplotype linkage analysis to detect alleles carrying microdeletions, and CNVs of embryos were identified to determine euploid identity. Amniotic fluid tests were performed in the second trimester to verify the PGT-M results. RESULTS: All couples were tested for chromosomal microdeletions, with deletion fragments ranging in size from 1.60 to 1.73 Mb, and one partner in each couple did not carry the microdeletion. Three couples successfully underwent PGT-M assisted conception and obtained healthy live births. CONCLUSION: This study shows that haplotype linkage analysis by karyomapping could effectively detect the carrier status of embryos with microdeletions at the single-cell level. This approach may be applied to the preimplantation diagnosis of various chromosomal microvariation diseases.

The successful strategy of comprehensive pre-implantation genetic testing for beta-thalassaemia-haemoglobin E disease and chromosome balance using karyomapping.

Thalassaemia is the commonest monogenic disease and causes a health and economic burden worldwide. Karyomapping can be used for pre-implantation genetic testing of monogenic disorders (PGT-M). This study applied karyomapping in two PGT-M cycles and made a comparison to polymerase chain reaction (PCR). Two families at risk of having beta-thalassaemia-haemoglobin E disease offspring decided to join the project and informed consent was obtained. Karyomapping results of family A (beta-thalassaemia (c.41_42delTCTT)-Hb E (c.26G>A) disease) revealed four normal, two beta-thalassaemia traits, one Hb E trait and six affected. Three embryos exhibited unbalanced chromosomes. One normal male embryo was transferred. Karyomapping results of family B (beta-thalassaemia (c.17A>T)-Hb E (c.26G>A) disease) revealed six Hb E traits and three affected. Three embryos were chromosomally unbalanced. One Hb E trait embryo was transferred. Two successful karyomapping PGT-M were performed, including deletion and single-base mutations. Karyomapping provides accuracy as regards the protocol and copy number variation which is common in pre-implantation embryos. Impact StatementWhat is already known on this subject? Thalassaemia syndrome is the commonest monogenic disease and causes a health and economic burden worldwide. Modern haplotyping using SNP array (aSNP) and karyomapping algorithms can be used for pre-implantation genetic testing of monogenic disorders (PGT-M). However, few clinical karyomapping PGT-M cycles have been done and validated so far.What do the results of this study add? Two successful clinical PGT-M cycles for beta-thalassaemia (c.41_42delTCTT and c.17A>T mutations)-haemoglobin E (c.26G>A) disease were performed using karyomapping. The outcome was two healthy babies. Multiplex fluorescent polymerase chain reaction (PCR) with mini-sequencing was also used for confirmation mutation analysis results. PCR confirmed haplotyping results in all embryos. Six embryos from both PGT-M cycles exhibited unbalanced chromosomes evidenced by aSNP.What are the implications of these findings for clinical practice and/or further research? Karyomapping provides accurate information quickly and the outcomes of the study will save time as regards protocol development, provide a usable universal PGT-M protocol and add additional copy number variation (CNV) information, chromosome number variation being a common issue in pre-implantation embryos.

Aneuploidy and recombination in the human preimplantation embryo. Copy number variation analysis and genome-wide polymorphism genotyping.

RESEARCH QUESTION: What are the incidence and patterns of meiotic trisomies and recombination separately and in relation to each other at the blastocyst stage via single nucleotide polymorphism genotyping combined with array comparative genomic hybridization. DESIGN: Single nucleotide polymorphism microarrays were carried out on a total of 1442 blastocyst stage embryos derived from 268 fertile couples undergoing preimplantation genetic diagnosis for the purposes of avoiding transmittance of known single gene disorders to their offspring; 24-chromosome aneuploidy screening via array comparative genomic hybridization was carried out in parallel. RESULTS: One hundred per cent of meiotic trisomies identified in these embryos were of maternal origin and their incidence increased significantly with advancing maternal age (P < 0.0001). A total of 55.8% of meiotic trisomies were meiosis I-type and 44.2% were meiosis II-type. Certain chromosomes were affected more by meiosis I-type errors, whereas others experienced more meiosis II-type errors. A detailed recombination analysis was carried out for 11,476 chromosomes and 17,763 recombination events were recorded. The average number of recombination sites was 24.0 ± 0.3 for male meiosis and 41.2 ± 0.6 for female meiosis (autosomes only). Sex-specific differences were observed in the locations of recombination sites. Comparative analysis conducted between 190 euploid embryos and 69 embryos presenting maternal meiotic trisomies showed similar recombination rates (P = 0.425) and non-recombinant chromatid rates (P = 0.435) between the two categories; differences, however, were observed when analysing embryos affected with specific maternal meiotic trisomies. CONCLUSIONS: This study yielded unique data concerning recombination and the origin of aneuploidies observed during the first few days of life and provides a novel insight into these important biological processes.

Live births following preimplantation genetic testing for dynamic mutation diseases by karyomapping: a report of three cases.

PURPOSE: The preimplantation genetic testing for monogenic defects (PGT-M) is a beneficial strategy for the patients suffering from a Mendelian disease, which could protect their offspring from inheriting the disease. The purpose of this study is to report the effectiveness of PGT-M based on karyomapping for three cases of dynamic mutation diseases with trinucleotide repeat expansion. METHODS: PGT-M was carried out on three couples, whose family members were diagnosed with Huntington's disease or spinocerebellar ataxias 2 or 12. The whole genome amplification was obtained using the multiple displacement amplification (MDA) method. Then, karyomapping was performed to detect the allele that is carrying the trinucleotide repeat expansion using single nucleotide polymorphism (SNP) linkage analyses, and the copy number variations (CNVs) of the embryos were also identified. Prenatal diagnosis was performed to validate the accuracy of PGT-M. RESULTS: PGT-M was successfully performed on the three couples, and they accepted the transfers of euploid blastocysts without the relevant pathogenic allele. The clinical pregnancies were acquired and the prenatal diagnosis of the three families confirmed the effectiveness of karyomapping. The three born babies were healthy and free of the pathogenic alleles HTT, ATXN2, or PPP2R2B corresponding to Huntington's disease, spinocerebellar ataxias 2 or 12, respectively. CONCLUSION: This study shows that karyomapping is a highly powerful and efficient approach for dynamic mutation detection in preimplantation embryos. In this work, we first report the birth of healthy babies that are free of the pathogenic gene for dynamic mutation diseases in patients receiving PGT-M by karyomapping.

Incidence and origin of meiotic whole and segmental chromosomal aneuploidies detected by karyomapping.

RESEARCH QUESTION: What is the incidence and origin of meiotic whole and segmental aneuploidies detected by karyomapping at a blastocyst stage in human-derived IVF embryos? What is the distribution of various types of errors, including rare chromosomal abnormalities? DESIGN: The incidence of chromosomal aneuploidies was assessed in 967 trophectoderm biopsies from 180 couples who underwent 215 cycles of IVF with preimplantation genetic testing for monogenetic disease with a known causal mutation with a mean maternal age of 32.7 years. DNA from both parents and a reference sample was genotyped together with the analysed trophectoderm samples by karyomapping (single-nucleotide-polymorphism-based array). RESULTS: Chromosomal abnormalities were detected in 31% of the analysed samples. At least one whole chromosomal aneuploidy was detected in 27.1% of the trophectoderm biopsies, whereas a segmental aneuploidy was detected in 5.1% of the trophectoderm biopsies. Our results reveal that segmental aneuploidies predominantly affect paternally derived chromosomes (70.4%; P < 0.01) compared with whole chromosomal aneuploidies that more frequently affect maternally derived chromosomes (90.1%; P < 0.0001). Also, the frequency of meiosis I (MI) and meiosis II (MII) errors was established in meiotic trisomies; MI errors were observed to be more frequent (n = 102/147 [69.4%]) than MII errors (n = 45/147 [30.6%]). CONCLUSIONS: Karyomapping is a robust method that is suitable for preimplantation genetic testing for monogenetic disease and for detecting meiotic aneuploidies, including meiotic segmental aneuploidies, and provides complex information about their parental origin. Our results revealed that segmental aneuploidy more frequently affects paternal chromosomes compared with whole chromosomal aneuploidy in human IVF embryos at the blastocyst stage.

Karyomapping in preimplantation genetic testing for ß-thalassemia combined with HLA matching: a systematic summary.

PURPOSE: To investigate the validity, accuracy, and clinical outcomes of Karyomapping in preimplantation genetic testing (PGT) for ß-thalassemia combined with human leukocyte antigen (HLA) matching. METHODS: A total of 128 cycles from January 2014 to December 2017 were identified, and 1205 embryos were biopsied. The case group included 88 cycles using Karyomapping for PGT-HLA, compared with 40 cycles using polymerase chain reaction-short tandem repeat (PCR-STR) as the control group. RESULTS: There were significant differences in the HLA matching rate (21.34 vs. 14.37%), the matched transferable embryo rate (9.79 vs. 14.07%), the clinical pregnancy rate (65.08 vs. 41.86%), and the spontaneous miscarriage rate (2.44 vs. 22.22%) between the case and control groups. In the case group, nearly 1/3 (33.37%) of the embryos showed aneuploidy. According to the results of single nucleotide polymorphism (SNP) haplotype analysis, the recombination rates of HBB (hemoglobin subunit beta) and HLA were 11.46% and 5.61% respectively. HLA gene recombination was mostly distributed between HLA-A and HLA-B and the downstream region of HLA-DQB1. In addition, STR analysis could be considered in the case of copy-neutral loss of heterozygosity (LOH) in the region where the HLA gene is located. CONCLUSION: Karyomapping contributes to accurate selection of matched embryos, along with aneuploidy screening. However, STRs assist identification in cases of LOH in the target region.

Preimplantation genetic testing using Karyomapping for a paternally inherited reciprocal translocation: a case study.

PURPOSE: Preimplantation genetic testing (PGT) using Karyomapping is used to screen embryos for single gene disorders prior to implantation. While Karyomapping is not designed to screen for abnormalities in chromosome copy number, this testing is based upon a genome-wide analysis of single nucleotide polymorphisms (SNP) and, as such, some chromosome abnormalities are detected. The aim of this study was to validate whether Karyomapping could provide reliable and accurate PGT for a paternal 46,XY,t(10;19)(p15;p13.3) reciprocal translocation. METHODS: Feasibility/validation for PGT was performed using DNA from the couple, as well as DNA from the paternal parents and from a previous unbalanced pregnancy. Karyomapping was performed using Illumina's HumanKaryomap-12 BeadChip microarray technology. SNP analysis was performed using BlueFuse Multi software (Illumina). Transmission of the translocation was assessed through the analysis of SNP markers on the chromosome regions of interest. RESULTS: PGT-SR was determined to be feasible as chromosomal SNP analysis could reliably distinguish normal/balanced outcomes from all unbalanced outcomes. The couple transferred a normal/balanced embryo in an elective single embryo transfer procedure following 2 IVF/PGT-SR cycles. A clinical pregnancy was achieved. CONCLUSION: This is the first report of PGT-SR test validation using Karyomapping for a 46,XY,t(10;19)(p15;p13.3) reciprocal translocation. Karyomapping may offer a means of detecting unbalanced forms of chromosome rearrangements when other PGT platforms fail.

Karyomapping: a single centre's experience from application of methodology to ongoing pregnancy and live-birth rates.

This study aimed to determine whether karyomapping can be applied to couples requiring preimplantation genetic diagnosis (PGD) for single gene disorder (SGD) and/or chromosomal rearrangement. 75/82 (91.5%) and 6/82 (7.3%) couples were referred for autosomal SGD and X-linked disease, respectively. One couple (1.2%) was referred for SGD and chromosomal rearrangement. Of 608 embryos, 146 (24%, 95% CI 21-28) day-3 and 462 (76%, 95% CI 72-79) blastocyst biopsies were performed. A total of 81 embryo transfers were performed; 16/81 (20%) were following day-3 embryo biopsy, 65/81 (80%) were following blastocyst biopsy and cryopreserved embryo transfer. Of 81 embryo transfers with known pregnancy outcome, 51 (63%, 95% CI 52-73) were on-going pregnancies, 6/81 (7%, 95% CI 3-15) resulted in first trimester miscarriages and 24/81 (30%, 95% CI 21-40) were failed implantations. Of the 51 on-going pregnancies, 15 (29%, 95% CI 19-43) couples had a singleton live birth at the time of write up. There have been no reports of abnormal prenatal, genetic testing or diagnosis of phenotype at birth. Karyomapping is reliable, efficient and accurate for couples requiring PGD for SGD and/or chromosomal rearrangement. Additionally, it provides aneuploidy screening, minimising risks of miscarriage and implantation failure.