Complex Disease Research Articles

Muscle Organoid and Assembloid Systems.

Skeletal muscle is one of the most complex and largest tissues that perform important processes in the body, including performing voluntary movements and maintaining body temperature. Disruption of muscle homeostasis results in the development of several disorders, including diabetes and sarcopenia. To study the developmental and regenerative dynamics of skeletal muscle and the mechanism behind muscle diseases, it is important to model skeletal muscle and diseases in vitro. Since skeletal muscle has a complex structure and interaction with other tissues and cells that are required to perform their function, conventional 2D cultures are not sufficient to model the skeletal muscle with their interactions. Advances in the field of organoids and assembloids will enable the establishment of more complex and realistic tissue or disease models which cannot be fully recapitulated in conventional 2D culture systems for use in several areas, including disease research, regenerative, and tissue biology. To overcome these limitations, 3D organoid systems and assembloid systems are promising because of their success in recapitulating the complex structural organization, function, and cellular interactions of skeletal muscle.

Exploring the evidence for mitochondrial dysfunction and genetic abnormalities in the etiopathogenesis of tropical ataxic neuropathy.

Tropical ataxic neuropathy (TAN) is characterised by ataxic polyneuropathy, degeneration of the posterior columns and pyramidal tracts, optic atrophy, and sensorineural hearing loss. It has been attributed to nutritional/toxic etiologies, but evidence for the same has been equivocal. TAN shares common clinical features with inherited neuropathies and mitochondrial disorders, it may be hypothesised that genetic abnormalities may underlie the pathophysiology of TAN. This study aimed to establish evidence for mitochondrial dysfunction by adopting an integrated biochemical and multipronged genetic analysis. Patients (n = 65) with chronic progressive ataxic neuropathy with involvement of visual and/or auditory pathways underwent deep phenotyping, genetic studies including mitochondrial DNA (mtDNA) deletion analysis, mtDNA and clinical exome sequencing (CES), and respiratory chain complex (RCC) assay. The phenotypic characteristics included dysfunction of visual (n = 14), auditory (n = 12) and visual + auditory pathways (n = 29). Reduced RCC activity was present in 13 patients. Mitochondrial DNA deletions were noted in five patients. Sequencing of mtDNA (n = 45) identified a homoplasmic variant (MT-ND6) and a heteroplasmic variant (MT-COI) in one patient each. CES (n = 45) revealed 55 variants in nuclear genes that are associated with neuropathy (n = 27), deafness (n = 7), ataxia (n = 4), and mitochondrial phenotypes (n = 5) in 36 patients. This study provides preliminary evidence that TAN is associated with a spectrum of genetic abnormalities, including those associated with mitochondrial dysfunction, which is in contradistinction from the prevailing hypothesis that TAN is related to dietary toxins. Analysing the functional relevance of these genetic variants may improve the understanding of the pathogenesis of TAN.

Sex contribution to average age at onset of Huntington's disease depends on the number of (CAG)n repeats.

Huntington's disease (HD) is a hereditary neurodegenerative disorder caused by the extension of the CAG repeats in exon 1 of the HTT gene and is transmitted in a dominant manner. The present study aimed to assess whether patients' sex, in the context of mutated and normal allele length, contributes to age on onset (AO) of HD. The study population comprised a large cohort of 3723 HD patients from the European Huntington's Disease Network's REGISTRY database collected at 160 sites across 17 European countries and in one location outside Europe. The data were analyzed using regression models and factorial analysis of variance (ANOVA) considering both mutated allele length and sex as predictors of patients' AO. AO, as described by the rater's estimate, was found to be later in affected women than in men across the whole population. This difference was most pronounced in a subgroup of 1273 patients with relatively short variants of the mutated allele (40-45 CAG repeats) and normal alleles in a higher half of length distribution-namely, more than 17 CAG repeats; however, it was also observed in each group. Our results presented in this observational study point to sex-related differences in AO, most pronounced in the presence of the short mutated and long normal allele, which may add to understanding the dynamics of AO in Huntington's Disease.Trial registration: ClinicalTrials.gov identifier NCT01590589.

IL-27 Gene Therapy Ameliorates IPEX Syndrome Caused by Germline Mutation of Foxp3 Gene: A Major Role for Induction of IL-10.

Inactivating mutations of Foxp3, the master regulator of regulatory T cell development and function, lead to immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome in mice and humans. IPEX is a fatal autoimmune disease, with allogeneic stem cell transplant being the only available therapy. In this study, we report that a single dose of adeno-associated virus (AAV)-IL-27 to young mice with naturally occurring Foxp3 mutation (Scurfy mice) substantially ameliorates clinical symptoms, including growth retardation and early fatality. Correspondingly, AAV-IL-27 gene therapy significantly prevented naive T cell activation, as manifested by downregulation of CD62L and upregulation of CD44, and immunopathology typical of IPEX. Because IL-27 is known to induce IL-10, a key effector molecule of regulatory T cells, we evaluated the contribution of IL-10 induction by crossing IL-10-null allele to Scurfy mice. Although IL-10 deficiency does not affect the survival of Scurfy mice, it largely abrogated the therapeutic effect of AAV-IL-27. Our study revealed a major role for IL-10 in AAV-IL-27 gene therapy and demonstrated that IPEX is amenable to gene therapy.

A single gene mutation underpins metabolic adaptation and acquisition of filamentous competence in the emerging fungal pathogen Candida auris.

Filamentous cell growth is a vital property of fungal pathogens. The mechanisms of filamentation in the emerging multidrug-resistant fungal pathogen Candida auris are poorly understood. Here, we show that exposure of C. auris to glycerol triggers a rod-like filamentation-competent (RL-FC) phenotype, which forms elongated filamentous cells after a prolonged culture period. Whole-genome sequencing analysis reveals that all RL-FC isolates harbor a mutation in the C2H2 zinc finger transcription factor-encoding gene GFC1 (Gfc1 variants). Deletion of GFC1 leads to an RL-FC phenotype similar to that observed in Gfc1 variants. We further demonstrate that GFC1 mutation causes enhanced fatty acid β-oxidation metabolism and thereby promotes RL-FC/filamentous growth. This regulation is achieved through a Multiple Carbon source Utilizer (Mcu1)-dependent mechanism. Interestingly, both the evolved RL-FC isolates and the gfc1Δ mutant exhibit an enhanced ability to colonize the skin. Our results reveal that glycerol-mediated GFC1 mutations are beneficial during C. auris skin colonization and infection.

Comparison of Demographics: National Amyotrophic Lateral Sclerosis Registry and Clinical Trials Data.

To characterize the participant demographics in the Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) database compared with the web-portal National Amyotrophic Lateral Sclerosis (ALS) Registry (the Registry). Demographics and ALS symptom information were compared between the self-reported registrant data in the Registry web portal (2010-2021) and the latest available PRO-ACT data (updated August 2022), which is a collection of clinical trials data. Greater percentages of younger (≤ 59years old) but smaller percentages of older (60 + years old) participants were represented in PRO-ACT compared to Registry. Enrollment for minority race groups was greater in the Registry portal data, but race information was largely missing/unknown in PRO-ACT database. Median age at the time of diagnosis and age at the time of symptom onset were significantly higher for Registry enrollees compared to the participants of PRO-ACT. Symptom onset sites were similarly reported, but duration between self-noted symptom onset and diagnosis was slight, but significantly longer for the Registry enrollees (11 vs. 9months). Hispanic were as likely as non-Hispanic to participate in research studies, based on the Registry data. There was a notable difference in the age distribution and minority representation of enrollees between the PRO-ACT and Registry study populations. Age distribution in the PRO-ACT database skewed to a younger and less diverse cohort. Despite the clinical heterogeneity and complex disease mechanism of ALS, identifying the underrepresented demographic niche in the PRO-ACT and Registry study populations can help improve patient participation and criteria for patient selection to enhance generalizability.

Mesenchymal stem cells and their derived exosomes in multiple sclerosis disease: from paper to practice.

Multiple sclerosis (MS) is a chronic neurodegenerative, inflammatory, and demyelinating disease of the central nervous system (CNS). Current medicines are not sufficient to control the inflammation and progressive damage to the CNS that is known in MS. These drawbacks highlight the need for novel treatment options. Cell therapy can now be used to treat complex diseases when conventional therapies are ineffective. Mesenchymal stem cells (MSCs) are a diverse group of multipotential non-hematopoietic stromal cells which have immunomodulatory, neurogenesis, and remyelinating capacity. Their advantageous effects mainly rely on paracrine, cell-cell communication and differentiation properties which introduced them as excellent candidates for MS therapy. Exosomes, as one of the MSCs secretomes, have unique properties that make them highly promising candidates for innovative approach in regenerative medicine. This review discusses the therapeutic potential of MSCs and their derived exosomes as a novel treatment for MS, highlighting the differences between these two approaches.

Temporal stratification of amyotrophic lateral sclerosis patients using disease progression patterns.

Identifying groups of patients with similar disease progression patterns is key to understand disease heterogeneity, guide clinical decisions and improve patient care. In this paper, we propose a data-driven temporal stratification approach, ClusTric, combining triclustering and hierarchical clustering. The proposed approach enables the discovery of complex disease progression patterns not found by univariate temporal analyses. As a case study, we use Amyotrophic Lateral Sclerosis (ALS), a neurodegenerative disease with a non-linear and heterogeneous disease progression. In this context, we applied ClusTric to stratify a hospital-based population (Lisbon ALS Clinic dataset) and validate it in a clinical trial population. The results unravelled four clinically relevant disease progression groups: slow progressors, moderate bulbar and spinal progressors, and fast progressors. We compared ClusTric with a state-of-the-art method, showing its effectiveness in capturing the heterogeneity of ALS disease progression in a lower number of clinically relevant progression groups.

Epigenetic control of skeletal muscle atrophy.

Skeletal muscular atrophy is a complex disease involving a large number of gene expression regulatory networks and various biological processes. Despite extensive research on this topic, its underlying mechanisms remain elusive, and effective therapeutic approaches are yet to be established. Recent studies have shown that epigenetics play an important role in regulating skeletal muscle atrophy, influencing the expression of numerous genes associated with this condition through the addition or removal of certain chemical modifications at the molecular level. This review article comprehensively summarizes the different types of modifications to DNA, histones, RNA, and their known regulators. We also discuss how epigenetic modifications change during the process of skeletal muscle atrophy, the molecular mechanisms by which epigenetic regulatory proteins control skeletal muscle atrophy, and assess their translational potential. The role of epigenetics on muscle stem cells is also highlighted. In addition, we propose that alternative splicing interacts with epigenetic mechanisms to regulate skeletal muscle mass, offering a novel perspective that enhances our understanding of epigenetic inheritance's role and the regulatory network governing skeletal muscle atrophy. Collectively, advancements in the understanding of epigenetic mechanisms provide invaluable insights into the study of skeletal muscle atrophy. Moreover, this knowledge paves the way for identifying new avenues for the development of more effective therapeutic strategies and pharmaceutical interventions.

GRPa-PRS: A risk stratification method to identify genetically-regulated pathways in polygenic diseases.

Polygenic risk scores (PRS) are tools used to evaluate an individual's susceptibility to polygenic diseases based on their genetic profile. A considerable proportion of people carry a high genetic risk but evade the disease. On the other hand, some individuals with a low risk of eventually developing the disease. We hypothesized that unknown counterfactors might be involved in reversing the PRS prediction, which might provide new insights into the pathogenesis, prevention, and early intervention of diseases. We built a novel computational framework to identify genetically-regulated pathways (GRPas) using PRS-based stratification for each cohort. We curated two AD cohorts with genotyping data; the discovery (disc) and the replication (rep) datasets include 2722 and 2854 individuals, respectively. First, we calculated the optimized PRS model based on the three recent AD GWAS summary statistics for each cohort. Then, we stratified the individuals by their PRS and clinical diagnosis into six biologically meaningful PRS strata, such as AD cases with low/high risk and cognitively normal (CN) with low/high risk. Lastly, we imputed individual genetically-regulated expression (GReX) and identified differential GReX and GRPas between risk strata using gene-set enrichment and variational analyses in two models, with and without APOE effects. An orthogonality test was further conducted to verify those GRPas are independent of PRS risk. To verify the generalizability of other polygenic diseases, we further applied a default model of GRPa-PRS for schizophrenia (SCZ). For each stratum, we conducted the same procedures in both the disc and rep datasets for comparison. In AD, we identified several well-known AD-related pathways, including amyloid-beta clearance, tau protein binding, and astrocyte response to oxidative stress. Additionally, we discovered resilience-related GRPs that are orthogonal to AD PRS, such as the calcium signaling pathway and divalent inorganic cation homeostasis. In SCZ, pathways related to mitochondrial function and muscle development were highlighted. Finally, our GRPa-PRS method identified more consistent differential pathways compared to another variant-based pathway PRS method. We developed a framework, GRPa-PRS, to systematically explore the differential GReX and GRPas among individuals stratified by their estimated PRS. The GReX-level comparison among those strata unveiled new insights into the pathways associated with disease risk and resilience. Our framework is extendable to other polygenic complex diseases.

MicroRNA and renal fibrosis in autosomal dominant polycystic kidney disease: a longitudinal study.

Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary kidney disorder that may progress to kidney failure, accounting for 5-10% of all patients with end-stage kidney disease (ESKD). Clinical data, as well as molecular genetics and advanced imaging techniques have provided surrogate prognostic biomarkers to predict rapid decline in kidney function, nonetheless enhanced tools for assessing prognosis for ADPKD are stillneeded. The aim of this study was to analyze specific microRNAs involved in the pathogenesis of ADPKD and in the development of renal fibrosis, evaluating their potential role as predictors of renal function loss. We evaluated kidney function by estimated glomerular filtration rate (eGFR) in 32 ADPKD patients in different stages of kidney disease at T0 and after a 24-month follow up (T1). Patients were divided into two groups: Rapid disease progression ([RP], n 15) and Non-rapid disease progression ([NRP], n 17), according to the Mayo Clinic classification criteria. At T0, ADPKD patients underwent plasma sampling for quantitative analysis of h-miR-17-5p, h-miR-21-5p and h-miR-199a-5p microRNA expression, using the quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) method and a 3T magnetic resonance imaging (MRI), using an advanced MRI imaging protocol, for the quantification of total kidney volume (TKV), total perfusion volume (TPV) and total fibrotic volume (TFV). The expression of h-miR17-5p was higher (p < 0.05) in ADPKD patients with rapid disease progression. h-miR-17-5p, h-miR-21-5p and h-mir-199-5p showed a positive and significant correlation with the eGFR slope (mL/min/1.73 m2/year) (p < 0.05) but not with the eGFR at both T0 and T1. Both total fibrotic volume (cm3) and height-adjusted total fibrotic volume (cm3/m) were positively and significantly correlated to h-miR 21-5p and h-miR 199-5p (p < 0.05), but not to total kidney volume (cm3) and height-adjusted total kidney volume (cm3/m). The microRNAs we studied were associated with fibrosis and renal damage, suggesting their possible role as biomarkers able to identify ADPKD patients at high risk of disease progression regardless of the degree of kidney function, and therefore suitable for medical therapy, and may help uncovering new molecular mechanisms underlying cystogenesis.

Genetic and genomic analysis of Belgian Blue’s susceptibility for psoroptic mange

BackgroundPsoroptic mange, caused by Psoroptes ovis mites, is affecting Belgian Blue cattle’s welfare and production potential. The Belgian Blue cattle—known for its high degree of muscling, low feed conversion ratio and high beef quality—is highly susceptible for this disease.ResultsIn this study, we phenotyped 1975 Belgian Blue cattle from more than 100 different groups on commercial beef farms for their psoroptic mange susceptibility. Substantial individual differences were observed within these management groups, with lesion extent differences up to ± 15%. Animal models showed that estimated heritabilities were low for lesion extent and severe lesion extent (0.07 and 0.09, respectively) and 0.12 for the number of mites. A genome wide association study for mange susceptibility revealed signals on BTA6, BTA11, BTA15 and BTA24. In these regions, candidate genes GBA3, RAG2, and TRAF6 were identified.ConclusionsDespite the challenges in phenotyping for psoroptic mange due to the timing of screening, the continuous evolution of lesions and different management conditions, we successfully conducted a study on the genetic susceptibility to psoroptic mange in Belgian Blue cattle. Our results clearly indicate that psoroptic mange is under polygenic control and the underlying candidate genes should be studied more thoroughly. This is the first study providing candidate genes for this complex disease. These results are already valuable for Belgian Blue breeding, however, further research is needed to unravel the architecture of this disease and to identify causal mutations.

FMRI and gene therapy in adults with CNGB3 mutation

Achromatopsia is an inherited retinal disease that affects 1 in 30,000 to 50,000 individuals and is characterised by an absence of functioning cone photoreceptors from birth. This results in severely reduced visual acuity, no colour vision, marked sensitivity to light and involuntary oscillations of the eyes (nystagmus).In most cases, a single gene mutation prevents normal development of cone photoreceptors, with mutations in the CNGB3 or CNGA3 gene being responsible for ~80% of all patients with achromatopsia. There are a growing number of studies investigating recovery of cone function after targeted gene therapy. These studies have provided some promise for patients with the CNGA3 mutation, but thus far have found limited or no recovery for patients with the CNGB3 mutation.Here, we developed colour-calibrated visual stimuli designed to isolate cone photoreceptor responses. We combined these with adapted fMRI techniques and pRF mapping to identify if cortical responses to cone-driven signals could be detected in 9 adult patients with the CNGB3 mutation after receiving gene therapy.We did not detect any change in brain activity after gene therapy when the 9 patients were analysed as a group. However, on an individual basis, one patient self-reported a change in colour perception, corroborated by improved performance on a psychophysical task designed to selectively identify cone function. This suggests a level of cone sensitivity that was lacking pre-treatment, further supported by a subtle but reliable change in cortical activity within their primary visual cortex.

Rearrangements involving 11q23.3/KMT2A in adult AML: mutational landscape and prognostic implications - a HARMONY study.

Balanced rearrangements involving the KMT2A gene (KMT2Ar) are recurrent genetic abnormalities in acute myeloid leukemia (AML), but there is lack of consensus regarding the prognostic impact of different fusion partners. Moreover, prognostic implications of gene mutations co-occurring with KMT2Ar are not established. From the HARMONY AML database 205 KMT2Ar adult patients were selected, 185 of whom had mutational information by a panel-based next-generation sequencing analysis. Overall survival (OS) was similar across the different translocations, including t(9;11)(p21.3;q23.3)/KMT2A::MLLT3 (p = 0.756). However, independent prognostic factors for OS in intensively treated patients were age >60 years (HR 2.1, p = 0.001), secondary AML (HR 2.2, p = 0.043), DNMT3A-mut (HR 2.1, p = 0.047) and KRAS-mut (HR 2.0, p = 0.005). In the subset of patients with de novo AML < 60 years, KRAS and TP53 were the prognostically most relevant mutated genes, as patients with a mutation of any of those two genes had a lower complete remission rate (50% vs 86%, p < 0.001) and inferior OS (median 7 vs 30 months, p < 0.001). Allogeneic hematopoietic stem cell transplantation in first complete remission was able to improve OS (p = 0.003). Our study highlights the importance of the mutational patterns in adult KMT2Ar AML and provides new insights into more accurate prognostic stratification of these patients.

Implications of right aortic arch prenatal diagnosis: the multicentric nationwide ARCADE cohort

ObjectivesThis study aims to describe the various presentations of the prenatally diagnosed isolated right aortic arch (RAA), that is, without associated congenital heart defect and to evaluate the impact of...

Endoscopic Ultrasound-guided Jejunocolostomy for Management of Refractory Severe Obesity in a Post-gastric Bypass Patient.

Obesity is a complex disease process, which often requires multifactorial, patient-tailored strategies for effective management. Treatment options include lifestyle optimization, pharmacotherapy, endobariatrics, and bariatric metabolic endoscopy. Obesity-based interventions can be challenging in patient populations with severe obesity, particularly post-gastric bypass. We report the case of a non-surgical patient with a failed remote open gastric bypass, who underwent an endoscopic small bowel diversion procedure, resulting in partial caloric diversion, via the creation of an EUS-guided jejunocolostomy (EUS-JC). The procedure is an extension of prior reported EUS-guided and magnet-based small bowel bypass procedures, in this case, for the purposes of weight loss (Kahaleh et al., 1; Jonica et al. Gastrointest Endosc. 97(5):927-933, 2; Machytka et al. Gastrointest Endosc. 86(5):904-912, 3;). The procedure was performed without peri-procedural complications, with effective weight loss during follow-up. Endoscopic bariatric interventions that target the small bowel, such as EUS-JC, offer promising tools for obesity management and should be studied further. Numerous factors including lifestyle, psychosocial, genetic, behavioral, and secondary disease processes contribute to obesity. Severe obesity (defined as a BMI > 50kg/m2) is associated with increased morbidity and mortality with a significantly reduced response to treatment (Flegal et al. JAMA. 309(1):71-82, 4;). Weight regain can be noted in up to 50% of patients post-RYGB. In populations with severe obesity, there is an associated 5-year surgical failure rate of 18% (Magro et al. Obesity Surg. 18(6):648-51, 5;). These patients may not be surgical candidates for revision or can develop post-revision chronic protein-caloric malnutrition (Shin et al. Obes Surg. 29(3):811-818, 6;). Lifestyle, modification, pharmacotherapy, or endoscopic transoral reduction (TORe) can be effective generally; however, in patients with severe obesity, the total desired excess body weight loss may not likely be accomplished solely by these strategies. An endoscopic small bowel intervention that diverts a portion of caloric intake from small bowel absorption can potentially promote weight loss similar to a surgical lengthening of the Roux limb (Shah et al. Obes Surg. 33(1):293-302, 7; Hamed et al. Annal Surg. 274(2):271-280, 8;), in the sense that there is a reduction in the total small bowel surface area for absorption. Roux limb distalization can be effective for weight regain for post bypass patients. The EUS-JC technique aims to work similarly by reducing the total small bowel surface area utilized for absorption. Since this patient was deemed a non-surgical candidate, an EUS-guided jejunocolostomy was offered. Prior to the procedure, the patient established longitudinal care with our bariatric nutritionist and obesity medicine services. Extensive pre-bariatric labs were screened to rule out confounders for recurrent severe obesity. Intra-procedure, the patient received one dose of 500mg intravenous levofloxacin. Post-procedure, loperamide was prescribed every 8h as needed for post-procedure diarrhea. Within 2weeks, the patient was no longer taking anti-diarrheals. The post-procedure diet consisted of a liquid diet for 2days before advancement to a low-residue diet for 1month, and then a regular diet.

O-233 The current landscape for carrier screening in donor conception; a game of chance for donors and recipients?

Abstract Study question How do international regulatory and commercial factors influence donor carrier screening and pose dilemmas for donors, clinics, and recipients. Summary answer Inconsistencies in international carrier screening guidelines and practice for donor conception create a two-tier system for donors and recipients. What is known already Carrier screening is used to identify those who are at risk to have a child with an autosomal recessive or X-linked genetic disorder. Donor banks adopt a commercially viable approach for carrier screening for their market and export, which creates inequalities in donor recruitment and reproductive risk for recipients. For example, UK guidelines require donors to be screened only for cystic fibrosis, with non-European donors screened for conditions known to be more common by ancestry. Real-world pan-ethnic approaches, however, are taken in varying degrees in other countries via extended carrier screening, posing dilemmas for donors, recipients, and clinics. Study design, size, duration Using current available public information, 14 UK, European, and US donor banks were surveyed to understand the screening level for recessive conditions and how this was conveyed to the patient or clinic client. Separately, expanded carrier screening (ECS) results (283 - 502 genes) from 1742 prospective donors from a &amp;gt; 6 year period at a US sperm bank were analysed to calculate acceptance rates if minimal screening and exclusion criteria were applied. Participants/materials, setting, methods UK, European, and US donor gamete banks were identified and surveyed using public information (2023). Separately, internal data from a US sperm bank related to ECS results from 2017 – 2023 was extracted, collated, and evaluated against the UK donor sperm genetic screening guidelines. Main results and the role of chance All donor banks surveyed state donors are genetically screened. For recessive conditions, UK and European banks screened for a small panel of between 3-20 genes, published on a general screening page on the donor bank website, and exclude donors that are carriers. Some offer an additional paid ECS genetic matching service without revealing what the donor or recipient may be carriers for. US banks who perform ECS include these results with a donor profile; some banks exclude carriers of more common recessive disease, while others accept all donors regardless of carrier status. Results from the US sperm bank indicated that of 1742 prospective donors who had ECS, only 117 (6.7%) of carriers would have been reported if screening under minimal guidelines. 665 of the 782 US positive carrier donors would not have been identified as carriers if tested according to UK guidelines. This, together with the observed varying regulation and commercial ECS panels used by donor banks internationally, demonstrate a tiered system of information availability and sharing for reproductive risk knowledge for donors and recipients; recipients are not consistently informed of the limitations of screening of a selected donor, and acceptance of donors to programs is inconsistent. Limitations, reasons for caution The panel composition and number of genes are variable by commercial ECS provider and donor banks may vary their carrier screening policy or commercial ECS options over time. Additionally, other European countries may have differing recommendations in regards to carrier screening practices. Wider implications of the findings As donor sperm imports from within and outside Europe increase, registered donors within countries will present differing genetic risk. Review and implementation of current carrier screening guidelines are required to ensure consistency of methodology and availability of transparent information for donors, recipients, and clinics to consider the wider implications. Trial registration number not applicable

O-156 Trophectoderm biopsy for pre-implantation genetic testing (PGT) does not increase rates of placental abnormalities among singleton pregnancies conceived with in-vitro fertilization (IVF)

Abstract Study question Does trophectoderm biopsy for PGT affect placental pathology? Summary answer Trophectoderm biopsy does not increase rates of placental abnormalities among singleton pregnancies conceived with in-vitro fertilization (IVF). What is known already PGT, routinely performed at the blastocyst stage, is used to screen embryos for aneuploidy, structural rearrangements, and single-gene disorders. The association of ART with abnormal placentation and adverse pregnancy outcomes is known. Whether, in a similar fashion, the disruption of the trophectoderm contributes to increased rates of abnormal placentation, remains unknown. Study design, size, duration Data from 987 singleton livebirths with available placental pathology, who conceived following IVF/±PGT at a single academic fertility center between 01/2004 and 12/2019, were retrospectively reviewed. Placental abnormalities were classified as anatomic, inflammatory, infectious, and vascular (any features of fetal or maternal vascular malperfusion), by one expert perinatal pathologist using the Amsterdam Workshop Consensus definitions. Placental pathology was compared between PGT (n = 76) and non-PGT (fresh and frozen, n = 911) cycles. Participants/materials, setting, methods Primary Outcome Measures: incidence of anatomic, vascular (maternal and fetal side), infectious, and inflammatory placental abnormalities. Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated using generalized estimating equations regression to adjust for multiple deliveries per patient and for potential confounders [maternal age, body mass index (BMI:kg/m2), race, parity, infertility diagnosis, gestational age, infant gender, hypertensive disorders of pregnancy, IVF and FET protocol]. Main results and the role of chance Patients undergoing PGT were older than the non-PGT group [36.2(3.5) vs. 34.9(3.8) years, p = 0.006] and did not otherwise differ in AMH, BMI, and race. Overall, adjusted (Adj) OR (95%CI) did not reveal any differences between groups in anatomic [0.92(0.82-1.03)], inflammatory [1.03 (0.94-1.14)]), infectious [1.02 (0.9-1.16)], or vascular abnormalities [1.02(0.88-1.18)]. When limiting analysis to blastocyst biopsies/FET cycles only, adjOR did not show any differences in inflammatory [1.01 (0.89-1.13)]), infectious [1.02 (0.88-1.17)], or vascular abnormalities [1.01 (0.84-1.2)] between the PGT and non-PGT group. Interestingly, adjOR (95%CI) revealed lower odds for anatomic abnormalities in the PGT group (0.86 (0.76-0.98), p = 0.021, non-PGT: ref). A sub-analysis of programmed FET cycles revealed persistently lower odds of anatomic abnormalities among the PGT group [adjOR (95%CI): 0.77 (0.67-0.89), p &amp;lt; 0.001, non-PGT: ref]. Among anatomic abnormalities studied in the programmed FET cycles, marginal cord insertion showed a difference between the groups [adjOR(95%CI): 0.83 (0.73-0.95), p:0.007, non-PGT: ref ]. AdjOR(95%CI) showed no differences in inflammatory [ 1.01 (0.87-1.17)], infectious [1.01 (0.86-1.2)], and vascular [0.9 (0.73-1.1)] abnormalities between groups. Limitations, reasons for caution This study is limited by its retrospective nature. Although a large number of IVF placentas was included, the number of patients in the PGT compared to the non-PGT group was smaller potentially limiting our ability to detect subtle differences between groups. Wider implications of the findings Trophectoderm biopsy for PGT does not appear to increase risk for placental abnormalities, a reassuring finding given the increased incidence of abnormal placentation and adverse perinatal outcomes among IVF pregnancies. Trial registration number not applicable

O-117 Advances in PGT diagnostics - technologies beyond copy number

Abstract Genetic abnormalities are well recognised as the main factor contributing to the high rate of infertility, pregnancy loss and congenital abnormalities in humans. A prime example of this can be seen from recent studies showing that embryos identified as uniformly aneuploid following PGT-A have little to no reproductive potential. However, embryos shown to have no gross chromosomal abnormalities after PGT are not a guarantee of healthy pregnancy and many other undetected genetic issues are likely to influence embryo competence. Developments in both sample preparation and methods for DNA analysis are driving ever-increasing data yield from PGT platforms, permitting not only DNA quantitation, but also allowing qualitative evaluation of genotyping data in parallel. This opens the door to the possibility of overcoming some of the previous limitations of PGT, leading to a more comprehensive assessment of the genetic health and reproductive potential of embryos. How to use this increasing amount of information, and if it can tangibly improve test accuracy and clinical outcomes, remains open to debate. There is, for instance, no consensus on how to interrogate genotyping data for better distinction of clinically relevant aneuploidy as well as genome wide (ploidy) abnormalities and exogenous DNA contamination, which could impact the correct reporting of PGT results. There is also no consensus on the potential benefit of genotyping data to be used for the accurate distinction of meiotic recombination by linkage analysis, nor for fingerprinting of embryos to identify rare, but catastrophic, lab error events as a routine part of treatment. Finally, there is no clear path on how to utilise these improvements in embryo genotyping, to detect sub-chromosomal de novo genetic abnormalities that could impact embryo viability beyond the scope of current testing for chromosomal abnormalities alone. The aim of this presentation is therefore to focus on the current state of the ART and address the current and potential future uses of genotyping in PGT. Topics covered will include identification of biopsy sample contamination to determine the truth from the noise, through to how we can rescue embryos by utilising PGT as a molecular fertilisation check and how fingerprinting of embryo can be an invaluable tool in the clinic. The origin of aneuploidy will be explored and how genotyping is reshaping our understanding of aneuploidy landscape of the preimplantation embryo. From a more basic science perspective, the potential of genotyping to identify meiotic recombination will be discussed and how this fundamental element of human reproduction could be an important biomarker for reproductive competence. Lastly future perspectives on how the evolution of PGT technologies can bring us closer to the accurate detection of de novo genomic changes will be explored and how this is taking PGT-A beyond just aneuploidy detection. It is no secret that PGT for embryo selection continues to be a controversial area of reproductive medicine, and the field of PGT-A especially continues to show disquieting inconsistency in data analysis and reporting. This new era of genotyping brings with it information that can be used as a standardization tool helping to focus and facilitate improvements in the field of PGT for better and more consistent clinical reporting and outcomes.

Chronic mucocutaneous candidiasis due to signal transducer and activator of transcription 1 mutation in a Saudi patient: a case report

Chronic mucocutaneous candidiasis (CMC) is a primary immunodeficiency condition caused by a genetic abnormality that increases the risk of recurrent and persistent skin, nail and mucous membrane infections with Candida species, typically Candida albicans. Signal transducer and activator of transcription 1 (STAT 1) gene mutation is a genetic trigger that causes CMC, which increases the risk of infections, multisystem disorders and cancer susceptibility. We describe the first case of a Saudi female patient with clinical features of CMC with an underlying (STAT 1) gene mutation.