Parental Origin Research Articles

Maternally expressed OsFERTILIZATION INDEPENDENT ENDOSPERM1 regulates seed dormancy and aleurone development in rice.

Seed dormancy, an essential trait for plant adaptation, is determined by the embryo itself and the surrounding tissues. Here, we found that rice (Oryza sativa) FERTILIZATION INDEPENDENT ENDOSPERM1 (OsFIE1) regulates endosperm-imposed dormancy and the dorsal aleurone thickness in a manner dependent on the parent of origin. Maternally expressed OsFIE1 suppresses gibberellin (GA) biosynthesis in the endosperm by depositing trimethylation of lysine 27 on histone H3 (H3K27me3) marks on GA biosynthesis-related genes, thus inhibiting germination and aleurone differentiation. Knockout of rice GA 20-oxidase1 (OsGA20ox1) alleviated the phenotypic defects in osfie1. The aleurone-positive determinant Crinkly 4 (OsCR4) is another target of the OsFIE1-containing Polycomb repressive complex 2 (PRC2). We found that OsFIE1 plays an important role in genomic imprinting in the endosperm of germinating seeds, particularly for paternally expressed genes associated with H3K27me3. The increased aleurone thickness of osfie1 substantially improved grain nutritional quality, indicating that the osfie1 gene may be utilized for breeding nutrient-enriched rice. The findings provide insights into the essential roles of PRC2-mediated H3K27me3 methylation in the acquisition of seed dormancy and endosperm cell differentiation in rice.

Changes of hemoglobin resulted by distant hybridization contributed to increased hypoxia tolerance of allotriploid crucian carp

Hypoxia tolerance, one of the important goals of fish breeding, is beneficial for aquaculture and the transporting of fish. Based on the bisexual fertile allotetraploid crucian carp hybrid lineage obtained by distant hybridization, we successfully developed the allotriploid crucian carp via interploidy crossing with diploid red crucian carp. This allotriploid fish exhibited obvious hypoxia tolerance with lower values of dissolved oxygen at Pcrit (critical oxygen press) and 50 % ASR (aquatic surface respiration) than its original parents. Hemoglobin is the main vector of oxygen in vivo. This study examined the changes in amino acid sequences and natural protein conformation of hemoglobin, and found that the Hbα sequences of allotriploid crucian carp displayed obvious hybridity, including recombination and variation, when compared with its original parents. Moreover, the expression of hbα gene is higher in the liver and blood of allotriploid crucian carp than in its original parents. After acute anoxia treatment, the expression of gata1 gene, which served as the general switch for erythroid development, decreased in the blood of all the three kinds of fish. However, only in the allotriploid crucian carp hbα gene expression significantly decreased, coupled with the erythrocytes displaying an increased ratio of nuclei/cytoplasm. Taken together, this study suggested that changes in hemoglobin coupled with the erythrocyte morphological alterations under hypoxia increased the hypoxia tolerance ability of allotriploid crucian carp, which would provide a new perspective to guide fish breeding to obtain high-quality fish species with increased hypoxia tolerance.

Increasing inequalities in mortality among individuals with a foreign background in Sweden

Abstract Background Previous research indicates that migrants in high-income destination countries not only experience a mortality advantage but also demonstrate lower or absent socioeconomic inequalities in mortality compared to the general native population. Yet the extent to which an income mortality gradient may also be evident among the descendants of migrants has been largely unexamined. Existing evidence has revealed that descendants of migrants face mortality risks higher than both migrants and their native-born peers. Methods This study utilizes longitudinal population registries covering the entire registered population of Sweden from 2004 to 2016. The study population comprises individuals aged 25 to 64, employing an open cohort design. Using Poisson regression, we examine the relationship between income rank position and cause-specific mortality among native-origin Swedes and eight nativity groups based on individuals’ country/region of birth, age of migration or parental origin. Results While foreign-born individuals who migrated as adults exhibited lower inequalities in all-cause mortality compared to native-origin Swedes, descendants of immigrants, particularly those with non-European backgrounds, show larger inequalities. Examination of specific causes of mortality revealed that external causes, notably accidents and assaults, account for increased disparities among non-European foreign-born men who migrated during childhood and male descendants of immigrants with non-European backgrounds. Conclusions Income-related inequalities in mortality are less pronounced among migrants compared to the native-born majority population in Sweden and tend to be higher among descendants of migrants, depending on gender and parental origin. The analysis highlights the role of external causes of mortality in shaping these inequalities, indicating that income disadvantages, augmented by a migrant background during upbringing, amplify specific health risks within these groups. Key messages • The study reveals lower mortality inequalities among migrant adults but a higher magnitude of inequalities among male descendants of immigrants, especially with non-European backgrounds. • Income disparities, combined with migrant backgrounds, amplify health risks among descendants of migrants in Sweden, underscoring the need for tackling social inequalities.

Chromosomal analysis of progenies between Lilium intersectional hybrids and wild species using ND-FISH and GISH.

Intersectional hybrids in lilies possess significant breeding value, but the lack of complete lily genomes and complex genotypes pose challenges for early identification of lily hybrids. This study aimed to use intersectional hybrid cultivars as female parents and wild lilies as male parents to facilitate early identification of hybrid offsprings and enhance the efficiency and convenience of the process. We investigated the nature of cross combinations using Non-denaturing Fluorescence In Situ Hybridization (ND-FISH) and Genomic In Situ Hybridization (GISH) techniques. Three novel oligonucleotide probes-Oligo-pTa794, Oligo-pITS and Oligo-telo-were developed for lily chromosome research. Our results demonstrated successful hybridization between wild lilies and intersectional hybrid cultivars, producing a total of 130 hybrid progenies. The combination of ND-FISH and GISH analyses effectively revealed the genomic composition of the hybrid progeny and determined the parental origin of specific chromosomes. This research provides significant guidance for lily breeding practices and offers a valuable reference for the application of ND-FISH and GISH techniques in interspecific hybridization breeding and molecular cytogenetic research across various plant species. The methods developed enable more precise, efficient, and convenient identification of hybrid offsprings.

A method for determining potential parental contamination: linkage disequilibrium-based log-likelihood ratio analysis for IVF-PGT

BackgroundAt present, embryologists are attempting to use conventional in vitro fertilization (cIVF) as an alternative to intracytoplasmic sperm injection (ICSI) for preimplantation genetic testing (PGT). However, the potential parental contamination origin of sperm cells and cumulus cells is considered the main limiting factor in the inability of cIVF embryos to undergo PGT.MethodsIn this study, we established an IVF-PGTA assay for parental contamination tests with a contamination prediction model based on allele frequencies and linkage disequilibrium (LD) to compute the log-likelihood ratio (LLR) under competing ploidy hypotheses, and then verified its sensitivity and accuracy. Finally, comparisons of the effectiveness of SNP-based analysis and LLR-based IVF-PGTA among 40 cIVF embryos was performed, based on both statistical analysis of the parental contamination rate and chromosomal ploidy concordance rate between TE biopsy and ICM isolations.ResultsWith IVF-PGTA assay, biopsies with 10% maternal contamination could be detected accurately, and contamination caused by sperm cells could be eliminated completely. Utilizing LLR-based or single Nucleotide Polymorphism (SNP) -based analyses, our comprehensive examination of 40 clinically discarded fresh cIVF embryos revealed an absence of paternal contamination. Strikingly, the LLR-based analysis uniquely revealed a mere instance of 24% maternal contamination within the trophectoderm cell (TE) biopsy of 5* embryo. Furthermore, it was solely through this analysis that embryo (9-F) was identified as a triploid of paternal origin.ConclusionsIn this study, we developed a new bioinformatics analysis method for identifying parental contamination during IVF-PGT, especially for couples with nonmale factor infertility.

Prevalence of Autosomal Monosomy and Trisomy Estimated Using Single Nucleotide Polymorphism Genotype Intensity Chip Information in a Large Population of Juvenile Dairy and Beef Cattle.

Aneuploidy, a genetic condition characterised by the deletion (monosomy) or duplication (trisomy) of a chromosome, has been extensively studied in humans, particularly in the context of trisomy on chromosome 21, also known as Down syndrome. Research on autosomal aneuploidy in live-born cattle has been limited to case reports, resulting in a lack of prevalence estimates of aneuploidy in cattle. Furthermore, the viability or lethality of aneuploidy on specific autosomes in cattle has not been well documented. The objective of this study was to estimate the prevalence of autosomal aneuploidy in a large population of new-born and juvenile beef and dairy cattle using single nucleotide polymorphism (SNP) chip genotype intensity data. Of the population of 779,138 cattle genotyped when younger than 15 months of age, 139 cattle (i.e., 0.017%) were diagnosed with one case of autosomal trisomy. Trisomy in only 10 different autosomes were detected (BTA 4, 6, 12, 15, 20, 24, 26, 27, 28 and 29) albeit the one case of trisomy detected on Bos taurus autosome (BTA) 4 was in an additional population of 341,927 cattle that were genotyped at > 15 months of age and was therefore excluded from prevalence estimates to minimise bias. The prevalence of trisomy per chromosome was generally inversely related to the length of the chromosome. Although the number of affected individuals was few, there was no evidence of differences in prevalence by breed, inbreeding level or parental age. The parental origin of the detected cases of trisomy was maternal for 92% of the cases. No cases of monosomy were detected despite the large dataset, which included calves genotyped at birth, indicating the potential lethal nature of monosomy in cattle. Cytogenetic testing was used to verify three of the animals with detected autosomal trisomy who were still alive. Eighteen of the 139 animals identified with autosomal trisomy were recorded as being stillborn, resulting in a prevalence of autosomal aneuploidy in live-born cattle of 0.015%. Of the 121 live-born cattle with autosomal trisomy, a total of 68 died on farm at, on average (standard deviation), 6.8 (8.7) months of age. All animals with autosomal trisomy on BTA 6, 12, 15, 20 or 24 were either stillborn or died on farm within 15 days of birth. This study is the first report of trisomy on BTA 4, 6, 15, 20 and 27 in live-born cattle, as well as the first to document fertile cows with trisomy on BTA 4, 27 or 28. Given that genotype intensity SNP data from SNP-chips are readily available, identifying animals affected with autosomal aneuploidy as well as quantifying and monitoring the incidence can be easily undertaken.

Disparities in overall and site-specific cancer mortality among immigrant generations in Sweden: A nationwide follow-up study over three decades.

We examined the overall and site-specific cancer mortality disparities among first-generation - separately in adults (G1) and children (G1.5) at immigration - and second-generation (G2) immigrants and their countries of origin using population-based registries in Sweden, encompassing over 8.5 million individuals aged 20 and above residing in Sweden since 1990, with follow-up until December 31, 2023. Cox proportional hazard models were fitted, stratified by gender, to estimate hazard ratios and 95% confidence intervals compared to natives. Mortality rates for most cancers transitioned from lower in G1 towards the rate of natives in G2. However, elevated mortality rates were sustained across generations for liver cancer in males and stomach cancer in females. Among G2, mortality from lymphohematopoietic cancers in males, and lung and cervix uteri cancers in females were elevated - by 10%, 9%, and 17% respectively compared to natives. Country of origin analyses revealed substantial disparities. For instance, G2 females with Nordic parental origin had a 13% higher risk of death from lung cancer, while those with non-Western parental origin had a 54% lower risk as compared to natives. These findings suggest a generational and arrival-age dynamics of cancer mortality and highlight target groups for cancer prevention and control among immigrants.

Impacts of paternal latitudinal origin on herbivore response strategies in Lythrum salicaria

Plants have evolved different strategies to withstand and respond to herbivore stress. The two main strategies plants employ under herbivore stress are known as tolerance and induced resistance. Tolerance is the ability to maintain high fitness despite experiencing high levels of herbivore damage. While induced resistance typically involves changing the concentrations of internal secondary metabolites as a response to initial herbivory and to prevent further damage. These strategies can lead to fitness differences between populations that vary by latitudinal origin. Previous studies have focused on the occurrence of herbivore response in general, whereas this study will make a direct comparison between response types and their fitness implications. Our study investigates whether eastern North American populations of Lythrum salicaria respond differently to herbivore stress. F1 crosses between L. salicaria individuals with different parental latitudinal ranges were grown in a common garden under two experimental herbivory treatments (pesticide sprayed vs. no pesticide) at the Queen’s University Biological Station. To identify differences in herbivore tolerance, we measured plant growth and development over 13 weeks and quantified herbivore damage, caused by the biocontrol beetle Galerucella calmariensis. A 48-hour feeding assay was then conducted to identify differences in herbivore resistance between populations. This assay provided beetles with a choice between young and old L. salicaria leaves from each experimental treatment. Our preliminary analysis of the feeding assay showed differences in leaf damage between parental lines. The initial analysis also showed that older leaves generally experienced more damage than younger leaves over the course of the 48-hour period. These results indicate population differences in herbivory stress response and differences in stress response effectiveness that varies with plant age. This experiment showed that L. salicaria individuals have varying degrees of herbivore stress response and effectiveness. However, further analysis that includes reproductive outputs and developmental differences will be completed to clearly identify the type of strategies L. salicaria populations with different parental latitudinal origins employ in response to herbivore damage.

Deep Screening for X Chromosome Parent-of-Origin Effects on Neurobehavioral and Neuroanatomical Phenotypes in 47,XXY Klinefelter Syndrome

BackgroundX chromosome parent of origin (POX) has been proposed as a source of phenotypic variation within sex chromosome aneuploidies such as Klinefelter syndrome (XXY/KS) and between XX and XY individuals. However, previous studies have yielded conflicting results regarding the presence and nature of POX effects, which we sought to clarify in an expanded sample with deeper neurobehavioral phenotyping. MethodsA cohort of 58 individuals with XXY/KS underwent duo or trio genome sequencing with parents (n = 151), measurement of 66 neurobehavioral phenotypes by standardized research assessments, and measurement of over 1000 anatomical phenotypes by structural magnetic resonance imaging. We developed a novel algorithm, the uniparental disomy visualization for variant call format files, to determine proband POX and then systematically tested for POX associations with all neurobehavioral and neuroanatomical outcomes. ResultsThe uniparental disomy visualization for variant call format files algorithm showed maternal POX in 35 of 58 cases (60.3%). There were no statistically significant POX effects on any of the 66 subscale measures of cognition, psychopathology, or behavior. Neuroimaging analysis identified 2 regions in the right hemisphere with significantly higher surface area (mean effect size = 1.20) among individuals with paternal versus maternal POX (q = .021). ConclusionsUsing deeper phenotyping in an expanded sample, we did not find evidence for substantial POX effects on neurobehavioral variability, except for localized unilateral modulations of surface area in the absence of co-occurring behavioral associations. These findings help to clarify previous inconsistencies in POX research and direct attention toward other sources of clinical variability in sex chromosome aneuploidies.

Risk Factors and 20-Year Time-Trend in Childhood Overweight and Obesity in Switzerland: A Repeated Cross-Sectional Study.

Background/Objective: Even though global childhood obesity rates keep increasing, stabilization has been shown over the past decade in several countries, including Switzerland. We aimed to investigate the trends in childhood overweight and obesity over the past 21 years in Switzerland and to identify the associated risk factors. Methods: Using cluster sampling, we recruited a national sample of 6-12-year-old children in Switzerland (n = 1245). We conducted anthropometric measurements and assessed risk factors using a self-administered questionnaire. We investigated the time trend by including data from four comparable previous surveys conducted since 2002. Results: We found a prevalence of overweight, including obesity, of 16.1 (14.1-18.2)%, with a significantly higher proportion in boys (18.6 (15.5-21.6)%) compared to girls (13.7 (11.0-16.4)%). We found a small but significant reduction in the prevalence of overweight including obesity over time (p = 0.005), but not of obesity alone (p = 0.099). The most important risk factors for obesity were parental education, parental origin, media consumption, as well as several dietary factors. Conclusions: Despite a slight decreasing trend in childhood overweight in Switzerland, it remains a public health concern. Prevention programs should focus on migrant families and those with low education and emphasize the risks of sedentary behavior and the importance of a healthy diet.

Isolation and comparative analysis of culturable bacterial communities associated with life stages, breeding and rearing substrates of Culicoides oxystoma Kieffer (Diptera: Ceratopogonidae) vector of bluetongue virus.

Culicoides oxystoma Kieffer (Diptera: Ceratopogonidae) has been vectoring several arboviruses, protozoa and nematodes, leading to mortality and morbidity of livestock and wild ruminants in the tropics and subtropics. Insight into the bacterial communities associated with the vector species must be worked out. This work tries to inventorize the bacterial communities associated with this important vector species. Acquisition of gut microbiota may be the parental origin, while some are obtained through feeding during larval stages. Culicoides oxystoma possesses semi-aquatic life cycle strategies for egg-laying and larval survival. The bacteria associated with C. oxystoma were compared throughout (i) life stages: egg, larval instars, pupa, adult: male and female obtained from laboratory colony; (ii) field-collected adult: male and age-graded females; and (iii) natural breeding substrate and artificial rearing substrate. The culture-dependent bacteria were identified by Sanger sequencing of 16S rRNA, and haemolytic bacteria were screened on blood agar. Results show that Firmicutes and Proteobacteria are the predominant Phyla, of which Bacillus spp. was the most abundant across the life stages. Across the life history, Bacillus cereus, Bacillus pumilus, Bacillus tropicus, Lysinibacillus sp. and Paenibacillus sp. were retrieved routinely. Bacillus cereus and Alcaligenes faecalis were detected in the lab-reared specimens and shared between the natural breeding site and rearing medium. From the adults trapped across two locations, B. cereus, Bacillus flexus, A. faecalis, Enterococcus faecium and Pseudomonas sp. were isolated. The bacterial species associated with this vector may influence various physiological traits, such as vectorial capacity, digestion and larval development, which need further investigation.

Uniparental maternal tetrasomy X co-occurrence with paternal nondisjunction: investigation of the origin of 48,XXXX

Tetrasomy X or 48,XXXX is a rare sex chromosome aneuploidy. The parental origin of tetrasomy X in a female patient with developmental delay was analyzed; all four X chromosomes were derived from the mother, and there were no paternally derived sex chromosomes. This finding indicates a rare incidental co-occurrence of maternal and paternal nondisjunction or polysomy rescue. The mechanism of 48,XXYY, which is related to developmental delay in males, was analyzed for comparison.

Genetic associations and parent-of-origin effects of PVRL1 in non-syndromic cleft lip with or without cleft palate across multiple ethnic populations.

This study investigated the associations of PVRL1 gene variants with non-syndromic cleft lip with or without cleft palate (NSCL/P) by evaluating transmission distortion and parent-of-origin (POO) effects in multiple ethnic populations. We conducted allelic and genotypic transmission disequilibrium tests (TDT) on 10 single-nucleotide variants (SNVs) in PVRL1 using data from 142 Korean families with an affected child. POO effects were analyzed using the POO likelihood ratio test, comparing transmission rates of maternally and paternally inherited alleles. To assess generalizability and ethnic heterogeneity, we compared results from Korean families with data from the Center for Craniofacial and Dental Genetics, which included 2,226 individuals from 497 European and 245 Asian trios. TDT analysis identified significant over-transmission of the rs7940667 (G361V) C allele in Korean families (p=0.007), a finding replicated in both Asian (p=6.5×10-7) and European families (p=1.6×10-10). Eight SNVs showed strong TDT evidence in larger Asian and European datasets after multiple comparison corrections (p<0.0073). Of these, 4 SNVs (rs7940667, rs7103685, rs7129848, and rs4409845) showed particularly robust association (p<5×10-8). POO analysis revealed significant maternal over-transmission of the rs10790330-A allele in Korean families (p=0.044). This finding was replicated in European families (p=9.0×10-4). Additionally, 3 other SNVs, rs7129848 (p=0.001) and the linked SNVs rs3935406 and rs10892434 (p=0.025), exhibited maternal over-transmission in the validation datasets. Our findings provide robust evidence supporting the associations of PVRL1 variants with NSCL/P susceptibility. Further research is necessary to explore the potential clinical applications of these findings.

Identification of Two Novel HIV-1 Unique Recombinant Forms (CRF01_AE/CRF07_BC) and Genomic Characterization in Tongzhou District of Beijing, China.

Continuous recombination and variation during replication could lead to rapid evolution and genetic diversity of HIV-1. Some studies had identified that it was easy to develop new recombinant strains of HIV-1 among the populations of men who have sex with men (MSM). Surveillance of genetic variants of HIV-1 in key populations was crucial for comprehending the development of regional HIV-1 epidemics. The finding was reported the identification of two new unique recombinant forms (URF 20110561 and 21110743) from individuals infected with HIV-1 in Tongzhou, Beijing in 2020-2022. Sequences of near full-length genome (NFLG) were amplified, then identification of amplification products used phylogenetic analyses. The result showed that CRF01_AE was the main backbone of 20110561 and 21110743. In the gag region of the virus, 20110561 was inserted two fragments from CRF07_BC, while in the pol and tat regions of the virus, 21110743 was inserted four fragments from CRF07_BC. The CRF01_AE parental origin in the genomes of the two URFs was derived from the CRF01_AE Cluster 4. In the phylogenetic tree, the CRF07_BC parental origin of 20110561 clustered with 07BC_N and the CRF07_BC parental origin of 21110743 clustered with 07BC_O. In summary, the prevalence of novel second-generation URFs of HIV-1 was monitored in Tongzhou, Beijing. The emergence of the novel CRF01_AE/CRF07_BC recombination demonstrated that there was a great significance of continuous monitoring of new URFs in MSM populations to prevent and control the spreading of new HIV-1 URFs.

Genomic imprinting and random monoallelic expression

In this review we consider mechanisms of monoallelic expression: genomic imprinting, in which gene transcription depends on the parental origin of the allele, and random monoallelic transcription. We summarize evidence for the regulation of activity in imprinted regions. Particular attention is paid to areas that control imprinting. Factors that may influence the variability of the imprintome are considered. The perspectives behind monoallelic expression studies are also discussed.

Modeling QTL-by-environment interactions for multi-parent populations.

Multi-parent populations (MPPs) are attractive for genetic and breeding studies because they combine genetic diversity with an easy-to-control population structure. Most methods for mapping QTLs in MPPs focus on the detection of QTLs in single environments. Little attention has been given to mapping QTLs in multienvironment trials (METs) and to detecting and modeling QTL-by-environment interactions (QEIs). We present mixed model approaches for the detection and modeling of consistent versus environment-dependent QTLs, i.e., QTL-by-environment interaction (QEI). QTL effects are assumed to be normally distributed with variances expressing consistency or dependence on environments and families. The entries of the corresponding design matrices are functions of identity-by-descent (IBD) probabilities between parents and offspring and follow from the parental origin of offspring DNA. A polygenic effect is added to the models to account for background genetic variation. We illustrate the wide applicability of our method by analyzing several public MPP datasets with observations from METs. The examples include diallel, nested association mapping (NAM), and multi-parent advanced inter-cross (MAGIC) populations. The results of our approach compare favorably with those of previous studies that used tailored methods.

O-066 Parental inheritance of monopronuclear blastocysts from ICSI cycles and its association with specific morphokinetic traits: a retrospective observational study

Abstract Study question Are monopronuclear-originated blastocysts from ICSI prone to have uniparental genome and does it correlate with specific morphokinetic parameters? Summary answer Extended compaction was notably observed in parthenogenetic monopronuclear blastocysts, suggesting a potential correlation between morphokinetic traits and parental origin. What is known already Previous studies indicated monopronuclear embryos with larger pronucleus exhibit a propensity to develop into blastocysts as normal fertilized embryos, which was considered as evidence supporting the presence of a diploid genome enclosed within a singular pronucleus.However, diploid blastocysts may also arise from haploid spontaneous diploidization following parthenogenetic or androgenetic activation, particularly in ICSI-derived blastocysts. Although certain characteristics were discerned in prior morphokinetic studies on monopronuclear blastocysts, these embryos were not proceeded to comprehensive chromosomal analysis to authenticate the association with parental inheritance, which requires further clarification and investigation. Study design, size, duration This retrospective cohort study, conducted in a university-affiliated reproductive medical center, focused on ICSI-derived monopronuclear blastocysts (n = 151) obtained from 145 PGT cycles spanning January 2013 to December 2022. Among these, nineteen were subject to morphokinetic analysis within a time-lapse system, while 35 bipronuclear-originated sibling blastocysts from the same cycles comprised the control group. Notably, the morphokinetic analysis incorporated 10 uniparental monopronuclear blastocysts, with 7 originating from parthenogenesis and the remaining from androgenesis. Participants/materials, setting, methods The data was collected from patients who had at least one biopsied ICSI-derived monopronuclear blastocyst between 2013 and 2022 at the reproductive center. The genetic analysis of blastocysts were performed using SNP array or NGS. Morphokinetic recordings were obtained from blastocysts cultured in time-lapse system along with euploid bipronuclear sibling blastocysts in the same cycles. All annotations underwent manual scrutiny and standardization by the same embryologist to ensure consistency. Main results and the role of chance This study explored links between genetic origin and morphokinetics in ICSI-derived monopronuclear blastocyst through combine analysis. Among 151 blastocysts, 53 (35.1%) were biparental euploidies, while 20% demonstrated uniparental patterns, with 18 confirmed as parthenogenetic and 7 as androgenetic. The ratio of parthenogenesis to androgenesis was 2.6:1, aligning with reported figures. Pronuclear metrics revealed that pronuclei area of monopronuclear blastocysts were notably larger (91∼171 μm2) than that of maternal-origin pronuclei but equivalent to paternal-origin pronuclei from bipronuclear blastocysts.Kinetic analysis indicated that pronuclei of monopronuclear blastocysts vanished 1.9 hours earlier than those of bipronuclear blastocysts, and furtherly biparental monopronuclear blastocysts had a 2.74-hour shorter visible duration compared to bipronuclear blastocysts, whereas uniparental monopronulcei showed no significant difference. Following pronucleus disappearance, the compaction period of monopronuclear blastocysts lasted 2.85 hours longer than bipronuclear blastocysts. Notably, in parthenogenetic uniparental monopronuclear blastocysts, this gap expanded to 10.92 hours. Additionally, there was a significantly higher proportion of asymmetrical halo and dysmorphism in monopronuclear blastocysts (78.95%, 63.16%) compared to bipronuclear blastocysts (40.00%, 34.29%), but neither differences was related to parental origins. The study corroborated a high incidence of uniparental diploidy and identified the discrepancies in pronuclear parameters and compaction before blastulation of monopronuclear blastocysts with different parental origins. Limitations, reasons for caution The scarcity of ICSI-derived monopronuclear blastocysts undergoing PGT and time-lapse culture posed challenges in discerning additional morphokinetic distinctions related to parental inheritance and conducting in-depth analyses for androgenetic blastocysts. It is noted that parental ploidy results from NGS were deduced from targeted chromosome, which may not represent the whole genome. Wider implications of the findings Our results confirmed the high risk of uniparental diploidy in ICSI-derived monopronuclear blastocysts, suggesting the necessity of comprehensive screening. We pinpointed morphokinetic features in monopronuclear embryos associated with parental origin. While it remains unreliable to gauge parental compositions through morphokinetics, these distinctions could serve as supplementary indicators evaluating monopronuclear embryos. Trial registration number not applicable

O-153 Clinical utility of preimplantation genetic testing for aneuploidy origin (PGT-AO) to enhance embryo selection for monogenic disorders: a retrospective pan-country integrative genomic and clinical study

Abstract Study question What is PGT-AO’s impact on implantation and pregnancy rate per embryo transfer, by determining the prevalence and effect of (mosaic) aneuploidies and their segregational origin? Summary answer PGT-AO potentially enhances the efficiency of PGT and increases the pregnancy rate per embryo transfer by minimizing transfers with poor outcomes and improving implantation rates. What is known already Demographic factors such as advanced parental age increases risk of aneuploid offspring, driving demand for advanced PGT. Randomized controlled trials revealed that PGT-A does not increase live birth rates after IVF. PGT-A, the most frequent form of PGT, overlooks the mosaic nature and segregational origin of aneuploidies in IVF embryos. This possibly leads to avoiding the transfer of mosaic embryos and reduces the pregnancy rate per cycle. Prompting this study, five embryos transferred based on PGT-M, led to trisomic pregnancies terminated following invasive prenatal diagnosis. Subsequent genome haplarithmisis revealed that these embryos carried (meiotic) trisomies not previously detected by PGT-M. Study design, size, duration In this retrospective study, we included 1944 embryos (816 PGT-M embryos, 323 couples, 224 indications). Currently, 284 have been processed by genome haplarithmisis-based PGT-AO and analyzed to assess if (mosaic) aneuploidies and segregational origin would have altered transfer decisions and subsequent clinical outcomes. We evaluated our novel PGT- A approach, termed PGT-AO, providing a nuanced understanding of early embryonic development in clinical practice and more responsible PGT-A, potentially leading to viable mosaic embryo transfer. Participants/materials, setting, methods The couples were counseled by clinical geneticists at Dutch University Medical Centers (UMCs), in Maastricht, Amsterdam, Utrecht, and Groningen, and enrolled in the diagnostic PGT-M procedure after signing an informed consent form. Embryos (n = 816) eligible for transfer based on absence of the monogenic aberration of interest by PGT-M were analyzed by haplarithmisis-based PGT-AO including parental information. This information allows for the detection of (mosaic) chromosomal abnormalities and their parental and segregational origin. Main results and the role of chance Of 816 included embryos (323 couples, 224 indications), 284 were found to be suitable for transfer by PGT-M and were analyzed by PGT-AO. Of these, 183 were transferred. Of the transferred embryos, 65 (35.5%) had a positive HCG and 48 (26.3%) resulted in a liveborn. 14.6% (7/48) carried abnormalities following our PGT-AO approach. These abnormalities consisted of mitotic mosaic trisomies, mosaic monosomies, and mosaic duplications and a deletion. Of the transferred embryos, 132 (72.1%) did not result in a liveborn and 115 (62.8%) had negative HCG tests. Of the transferred embryos with negative HCG, 38.3% (44/115) contained a total of 90 abnormalities, consisting of 37 monosomies, 35 trisomies, 12 deletions, 2 duplications, 2 UPD and 1 ring chromosome. The 35 trisomies occurred in 20 embryos, of which 9 were of meiotic origin and 5 of mitotic origin, 1 of both meiotic and mitotic, and 5 could not be determined. Based on these preliminary results, PGT-AO can avoid the transfer of embryos with aneuploidy of meiotic origin and non-mosaic status. In contrast, embryos with aneuploidy of mitotic origin are often mosaic and the abnormality may not be uniformly distributed throughout the blastocyst and could potentially be considered for transfer. Limitations, reasons for caution Haplarithmisis relies on the inclusion of parental DNA to phase the embryonic genome and thus determine the segregational origin of aberrations. Additionally, mitosis and meiosis II trisomies cannot be discerned where a crossover event is absent for a chromosome with trisomy. Wider implications of the findings Implementation of PGT-AO will re-define the current embryo selection system. This enhances PGT by increasing pregnancy rate per embryo transfer and minimizing transfers with poor outcomes, disposal of potentially viable embryos, spontaneous pregnancy losses, and termination of aneuploid pregnancies. This reduces the emotional and financial burdens on families and healthcare. Trial registration number Not applicable

P-560 Characterization of ploidy level and parental genome inheritance abnormalities in preimplantation human embryos

Abstract Study question Can preimplantation genetic testing (PGT) platforms with integrated genotyping aid the characterization of genome-wide chromosomal abnormalities in human embryos and factors contributing to their occurrence? Summary answer Signatures detected by genotype-criteria-based models in PGT pinpoint origin of haploidy, triploidy and genome-wide uniparental disomy (gwUPD), highlighting recombination deficiencies potentially underpinning these phenomena. What is known already While there is a growing body of knowledge on the frequency and origin of individual chromosome abnormalities, very little is known about genome-wide chromosomal abnormalities in human development. Indeed, genome-wide abnormalities are incompatible with normal human development, making the preimplantation stage the ideal time to characterize them. Novel PGT technologies provide the research and clinical opportunity to characterize both known ploidy-level abnormalities (triploid/haploid) and identify theoretical genome-wide abnormalities undetectable at later stages of development. Study design, size, duration PGT genotyping data from 96660 embryos were used to assess incidence of ploidy-level abnormalities and correlation with potential predisposing clinical factors. Parental origin of putative haploidy and triploidy was assessed on 14 and 41 embryos with parental genotypes available (trios), respectively. For the 41 triploid trios, meiotic origin and recombination rates were also evaluated. A novel genotype-criteria based model to detect theoretical gwUPD and meiotic origin was developed on a semi-contemporaneous 74009 female embryo dataset. Participants/materials, setting, methods PGT was performed with targeted next-generation sequencing, including 5000 genome-wide SNPs. Informative SNPs from trios were used to identify parental origin of haploidy/triploidy. Informative SNPs within 5cM of the centromere were used to evaluate meiotic origin and extended beyond 5cM to identify maternal recombination observing shifts between single (SPH) and biparental (BPH) homologs. gwUPD was predicted when low genome-wide heterozygosity, increased homozygosity in the centromeric region, and decreased similarity to sibling embryos were observed. Main results and the role of chance Genome wide ploidy abnormalities were detected in 1.1% (n = 1.063/96.660; CI 95%: 1-1,2%) of embryos. Haploidy was mainly of paternal origin (n = 12/14), whereas triploidy was exclusively maternal in origin (n = 41/41) and prominently due to meiosis II errors (n = 30/41; 73.2%; 95% CI:57.1-85.8%). Advanced maternal age was positively associated with an increased risk of triploid conceptions (OR = 1.059 per year; p &amp;lt; 0.001). Investigation of maternal recombination rates detected by three consecutive SNPs shifting between SPH and BPH (with a calculated genotyping error of 0.16%) in triploid embryos revealed an outlier group of 7 embryos with statistically lower (P &amp;lt; 0.001) identified crossover events (0-2 events genome-wide) compared to the average 23.7 detectable events genome-wide (SD:4.3). Recombinant gwUPD was predicted in 41 out of 74009 human embryos (0.05%; 95% CI:0.04-0.07%). These embryos showed a high homozygosity in pericentromeric regions, as a proof of each pair of chromosomes being the same parental homolog resulting from a faulty meiosis II, but with detectable heterozygosity regions throughout the rest of the genome, indicating that crossovers occurred between the two parental homologs during prophase I. Multifocal biopsies from the same embryos confirmed the reproducibility of identification of the number of recombination events in triploid embryos and the gwUPD prediction. Limitations, reasons for caution This assay genotypes only a portion of the genome and underestimation of recombination events is possible. Our current detection of gwUPD is limited to recombinant uniparental isodisomy of MII origin only. Therefore, the exact prevalence of these abnormal gwUPD configurations requires further understanding and analysis. Wider implications of the findings Genotyping in routine PGT can identify severe genome-wide abnormalities with associated gestational complications that would otherwise go undiagnosed. Comprehensive characterization of these abnormalities is not possible at later stages of development. Therefore, PGT offers a unique opportunity to delve into their biological origin and identify novel biomarkers for embryo competence. Trial registration number not applicable

O-035 Euploidy’s hidden potential: emerging insights from abnormal fertilized embryos

Abstract Study question Can pregnancies be achieved from abnormally fertilized embryos? Summary answer After conducting parental origin PGTA testing to confirm ploidy status, achieving pregnancy and live births becomes feasible. What is known already A major limitation in IVF is the availability of viable embryos per cycle. Particularly relevant for patients with poor prognosis in response to controlled ovarian stimulation. In these couples, the limited number of oocytes results in a significant reduction of the chance to achieve a live birth. In IVF, zygotes displaying successful extrusion of the 2PB and 2PN are considered “normally fertilized” and cultured further to be used for treatment. In contrast, zygotes showing a single or more than 2PN are deemed abnormally fertilized. However, some can ultimately develop into normal embryos, which may lead to live birth. Study design, size, duration This is a single centre retrospective observational study of 125 blastocysts classified as abnormal through standard fertilization check post-IVF (50 embryos) and ICSI (75 embryos) Embryos were subjected to genetic testing utilizing a validated targeted next-generation sequencing-based PGT-A protocol. The protocol's proven efficacy lies in distinguishing between haploid, diploid and triploid samples, a distinction made possible by the parallel analysis of genotyping data and chromosome copy number variations. Participants/materials, setting, methods The participants in this study were couples who underwent IVF cycles using PGT-A between 2021-2024. Embryos were divided into two groups based on their fertilization method Group A involved blastocysts derived from In vitro fertilization (IVF) = 50. Classified 1PN, micro 3PN, 3PN, and 4PN. Group B blastocysts derived from Intracytoplasmic sperm injection Intracytoplasmic sperm injection (ICSI) =75 Classified 1PN, micro 3PN, 3PN, and 4PN. Main results and the role of chance Group A: Involved embryos resulting from IVF; 54% were diploid, with 15% being euploid from 3PN. From 1PN, 92% were diploid, and 54% were euploid. Micro PN had a 100% diploid rate, of which 33% were euploid. No diploid embryos were reported from 4PN fertilization. Group B: Involved embryos resulting from ICSI; 36% were diploid, and 14% were euploid from 3PN. From 1PN, 53% were diploid, and 40% were euploid. Micro PN had a 100% diploid rate, with 23% being euploid. 4PN had a 50% diploid rate and no euploid embryos. On the other hand, 0.4% (17/4822) of 2PN-classified embryos were reported as haploid, and 1.4% (68/4822) of the 2PN-classified embryos were reported as polyploid. Eighty-nine percent of haploidy and polyploidy in ICSI originated maternally, while 71% of polyploidy in IVF originated paternally and only one embryo was haploid resulted from IVF was maternally originated. Remarkably, three live births were reported: one from 1PN, one from Micro PN, and the third from 3PN. Limitations, reasons for caution The data are observational and were retrospectively analyzed, so unknown confounders could not be assessed. Wider implications of the findings To our knowledge, this is the most extensive cohort study analyzing embryos resulting from abnormal fertilization. It has implications for clinical practice and gives an extra chance for patients, particularly those with a low number of eggs, in response to controlled ovarian stimulation. Trial registration number n/a