Monogenic Disorders Research Articles

Extreme founder effect associated with hyperglycemia and hyperlipidemia on the island of NIAS/Indonesia

The island of Nias/Indonesia shows an extremely reduced genetic diversity indicating a strong founder effect. As a consequence, the prevalence of some disease genes should significantly differ among populations depending on the gene pool passed on to the founder population and their successive expansion as it has already been documented for several monogenic diseases. Results of the current study based on routine laboratory blood examination give rise to the notion that this might also hold true for polygenic disorders. We observed very high prevalence of hyperglycemia (non-fasting glucose above 200 mg/dL in 14 % Nias population compared to 1.5 % in the population of the neighboring island of Sumatra) accompanied by hypertriglyceridemia, high non-HDL-cholesterol, and low HDL-cholesterol levels. These findings suggest that the Nias population may be disproportionally affected by prediabetes and type 2 diabetes mellitus. By contrast, laboratory parameters potentially indicative of other polygenic disorders such as total plasma cholesterol, electrolytes, creatinine, urea, and uric acid were comparable between the inhabitants of Nias and Sumatra islands. To our knowledge this is the first study suggesting that the extremely strong genetic bottleneck seen in the Nias population translates into the widespread metabolic disease with potentially deleterious influence on public health.

Mutation Analysis of Exon 1 in the Hemoglobin Subunit Beta (HBB) Gene in Beta-Thalassemia.

Introduction Thalassemia is a widely prevalent monogenic hematological disorder found worldwide. It exists in two forms: alpha- and beta-thalassemia. Alterations in the hemoglobin subunit beta (HBB) gene cause beta-thalassemia, with missense and point mutations affecting beta-globin synthesis. Consequently, genetic screening for beta-thalassemia is essential for genetic counseling, carrier screening, and prenatal diagnosis. Aim and objective This study aims to examine and identify mutations in the exon 1 region of the HBB gene in beta-thalassemia patients from the Vijayapura region. Methods This study involved 47 clinically diagnosed children with beta-thalassemia from a hospital in Vijayapura, India. Detailed clinical histories of all patients were recorded. Genomic DNA was extracted from the blood samples of these patients and subjected to polymerase chain reaction (PCR) using exon-specific primers for the HBB gene. The PCR products were then sequenced using the capillary-based Sanger sequencing method to identify mutations in the HBB gene. Results A total of 47 clinically diagnosed beta-thalassemia patients were included in the study, comprising 30 males and 17 females, aged between one and 20 years. Sequencing analysis of exon 1 in the beta-globin gene identified 17 beta-thalassemia variants. The most common mutation observed was T>G, G>C, C>A, and C>T in the exon 1 region of the HBB gene. Conclusion This study identifies the pattern of beta-thalassemia mutations, aiding in the prevention of the disorder through prenatal diagnosis and genetic counseling. Mutations can alter codon sequences, affecting protein production. Research highlights the importance of a primary prevention program to analyze mutations and sequence variations at the molecular level, thereby helping to address numerous genetic disorders.

Quetiapine, Clozapine, and Pimavanserin Treatment Response in Monogenic Parkinson's Disease Psychosis: A Systematic Review.

Psychotic symptoms frequently occur in idiopathic Parkinson's disease (PD) and often require treatment with antipsychotic therapy. Most antipsychotics have the potential to worsen the motor symptoms of PD; quetiapine, clozapine, and pimavanserin are commonly used for the treatment of idiopathic PD because these medications tend to be comparatively well tolerated. Although psychotic symptoms may also occur in monogenic forms of PD, no reviews have focused on the use of antipsychotic medications in this context. The objective of the present systematic review was to characterize the effectiveness and tolerability of quetiapine, clozapine, and pimavanserin in monogenic PD-associated psychosis. A literature search was performed with PubMed, Scopus, and Embase. The search yielded 24 eligible articles describing 30 individuals, although treatment response with respect to psychotic symptoms was described in only 11 cases; of these, six individuals experienced symptomatic improvement or remission (four with clozapine and two with quetiapine), two exhibited a poor therapeutic response (one to clozapine and one to quetiapine), and the other three responded initially to antipsychotic therapy before experiencing a recurrence of symptoms. The use of quetiapine and clozapine in GBA variant-associated PD is briefly reviewed separately. Notably, no reports of pimavanserin therapy were identified. In keeping with the idiopathic PD literature, relatively low doses of medication were used in most cases. Lastly, side effects were rarely reported. Although quetiapine and particularly clozapine may be effective and well tolerated in the treatment of monogenic PD psychosis, this review highlights the paucity of available evidence to guide clinical decision making in this context.

Haploinsufficiency in PTPN2 leads to early-onset systemic autoimmunity from Evans syndrome to lupus.

An exome sequencing strategy employed to identify pathogenic variants in patients with pediatric-onset systemic lupus or Evans syndrome resulted in the discovery of six novel monoallelic mutations in PTPN2. PTPN2 is a phosphatase that acts as an essential negative regulator of the JAK/STAT pathways. All mutations led to a loss of PTPN2 regulatory function as evidenced by in vitro assays and by hyperproliferation of patients' T cells. Furthermore, patients exhibited high serum levels of inflammatory cytokines, mimicking the profile observed in individuals with gain-of-function mutations in STAT factors. Flow cytometry analysis of patients' blood cells revealed typical alterations associated with autoimmunity and all patients presented with autoantibodies. These findings further supported the notion that a loss of function in negative regulators of cytokine pathways can lead to a broad spectrum of autoimmune manifestations and that PTPN2 along with SOCS1 haploinsufficiency constitute a new group of monogenic autoimmune diseases that can benefit from targeted therapy.

Application of multiple mosaic callers improves post-zygotic mutation detection from exome sequencing data

PurposeThe gold standard for identification of post-zygotic variants (PZVs) is droplet digital polymerase chain reaction or high-depth sequencing across multiple tissues types. These approaches are yet to be systematically implemented for monogenic disorders. We developed PZV detection pipelines for correct classification of de novo variants. MethodOur pipelines detect PZV in parents (gonosomal mosaicism [pGoM]) and children (somatic mosaicism, “M3”). We applied them to research exome sequencing (ES) data from the Australian Cerebral Palsy Biobank (n = 145 trios) and Simons Simplex Collection (n = 405 families). Candidate mosaic variants were validated using deep amplicon sequencing or droplet digital polymerase chain reaction. Results69.2% (M3trio), 63.9% (M3single), and 92.7% (pGoM) of detected variants were validated, with 48.6%, 56.7%, and 26.2% of variants, respectively, meeting strict criteria for mosaicism. In the Australian Cerebral Palsy Biobank, 16.6% of probands and 20.7% of parents had at least 1 true-positive somatic or pGoM variant, respectively. A large proportion of PZVs detected in Simons Simplex Collection parents (79.8%) and child (94.5%) were not previously reported. We reclassified 3.7% to 8.0% of germline de novo variants as mosaic. ConclusionMany PZVs were incorrectly classified as germline variants or missed by previous approaches. Systematic application of our pipelines could increase genetic diagnostic rate, improve estimates of recurrence risk in families, and benefit novel disease gene identification.

WES-based screening of 7,000 newborns: A pilot study in Russia

The effective implementation of whole-exome sequencing- and whole-genome sequencing-based diagnostics in the management of children affected with genetic diseases and the rapid decrease in the cost of next-generation sequencing (NGS) enables the expansion of this method to newborn genetic screening programs. Such NGS-based screening greatly increases the number of diseases that can be detected compared to conventional newborn screening, as the latter is aimed at early detection of a limited number of inborn diseases. Moreover, genetic testing provides new possibilities for family members of the proband, as many variants responsible for adult-onset conditions are inherited from the parents. However, the idea of NGS-based screening in healthy children raises issues of medical and ethical integrity as well as technical questions, including interpretation of the observed variants. Pilot studies have shown that both parents and medical professionals have moved forward and are enthused about these new possibilities. However, either the number of participants or the number of genes studied in previous investigations thus far has been limited to a few hundred, restricting the scope of potential findings. Our current study (NCT05325749) includes 7,000 apparently healthy infants born at our center between February 2021 and May 2023, who were screened for pathogenic variants in 2,350 genes. Clinically significant variants associated with early-onset diseases that can be treated, prevented, or where symptoms can be alleviated with timely introduced symptomatic therapy, were observed in 0.9% of phenotypically normal infants, 2.1% of the screened newborns were found to carry variants associated with reduced penetrance or monogenic diseases of adult-onset and/or variable expressivity, and 0.3% had chromosomal abnormalities. Here, we report our results and address questions regarding the interpretation of variants in newborns who were presumed to be healthy.

Infantile and Very Early Onset Inflammatory Bowel Disease: A Multicenter Study.

This study described disease characteristics and long-term outcomes in patients diagnosed with very early onset inflammatory bowel disease (VEOIBD) (diagnosed before 6 years of age) and infantile-IBD (before 2 years). Cases from 21 centers worldwide diagnosed with VEOIBD (2008-2018), with minimum 2 years of follow-up, were retrospectively reviewed. The cohort included 243 patients (52% males, median follow-up of 5.8 [range 2-18] years, including 69 [28%]) with infantile-IBD. IBD subtypes included Crohn's disease (CD), ulcerative colitis (UC), or IBD-unclassified (IBDU) in 30%, 59%, and 11%, respectively. Among patients with CD, 94% had colonic involvement, and among patients with UC/IBDU, 75% had pancolitis. Patients with infantile-IBD presented with higher rates of IBDU, lower hemoglobin and albumin levels, and higher C-reactive protein, and had lower response rates to first-induction therapy and corticosteroids therapy (P < .05 for all). Colectomy and diversion surgeries were performed in 11% and 4%, respectively, with no significant differences between age groups. Corticosteroid-free remission rates were 74% and 78% after 3 and 5 years, respectively, and 86% at end of follow-up. Genetic testing was performed in 96 (40%) patients. Among tested population, 15 (16%) were identified with monogenic disease. This group demonstrated lower response rates to induction therapies, higher rates of surgical intervention, and higher rates of major infections (P < .05 for all). Patients with VEOIBD, including infantile-IBD, exhibit low rate of complications and surgical interventions at the long term. Patients with monogenic IBD are at risk for more severe disease course.

In Utero Gene Therapy and its Application in Genetic Hearing Loss.

For monogenic genetic diseases, in utero gene therapy (IUGT) shows the potential for early prevention against irreversible and lethal pathological changes. Moreover, animal models have also demonstrated the effectiveness of IUGT in the treatment of coagulation disorders, hemoglobinopathies, neurogenetic disorders, and metabolic and pulmonary diseases. For major alpha thalassemia and severe osteogenesis imperfecta, in utero stem cell transplantation has entered the phase I clinical trial stage. Within the realm of the inner ear, genetic hearing loss significantly hampers speech, cognitive, and intellectual development in children. Nowadays, gene therapies offer substantial promise for deafness, with the success of clinical trials in autosomal recessive deafness 9 using AAV-OTOF gene therapy. However, the majority of genetic mutations that cause deafness affect the development of cochlear structures before the birth of fetuses. Thus, gene therapy before alterations in cochlear structure leading to hearing loss has promising applications. In this review, addressing advances in various fields of IUGT, the progress, and application of IUGT in the treatment of genetic hearing loss are focused, in particular its implementation methods and unique advantages.

Polyglutamine (PolyQ) Diseases: Navigating the Landscape of Neurodegeneration.

Polyglutamine (polyQ) diseases are a group of inherited neurodegenerative disorders caused by expanded cytosine-adenine-guanine (CAG) repeats encoding proteins with abnormally expanded polyglutamine tract. A total of nine polyQ disorders have been identified, including Huntington's disease, six spinocerebellar ataxias, dentatorubral pallidoluysian atrophy (DRPLA), and spinal and bulbar muscular atrophy (SBMA). The diseases of this class are each considered rare, yet polyQ diseases constitute the largest group of monogenic neurodegenerative disorders. While each subtype of polyQ diseases has its own causative gene, certain pathologic molecular attributes have been implicated in virtually all of the polyQ diseases, including protein aggregation, proteolytic cleavage, neuronal dysfunction, transcription dysregulation, autophagy impairment, and mitochondrial dysfunction. Although animal models of polyQ disease are available helping to understand their pathogenesis and access disease-modifying therapies, there is neither a cure nor prevention for these diseases, with only symptomatic treatments available. In this paper, we analyze data from the CAS Content Collection to summarize the research progress in the class of polyQ diseases. We examine the publication landscape in the area in effort to provide insights into current knowledge advances and developments. We review the most discussed concepts and assess the strategies to combat these diseases. Finally, we inspect clinical applications of products against polyQ diseases with their development pipelines. The objective of this review is to provide a broad overview of the evolving landscape of current knowledge regarding the class of polyQ diseases, to outline challenges, and evaluate growth opportunities to further efforts in combating the diseases.

Molecular and clinical characterization of a founder mutation causing G6PC3 deficiency.

G6PC3 deficiency is a monogenic immunometabolic disorder that causes syndromic congenital neutropenia. Patients display heterogeneous extra-hematological manifestations, contributing to delayed diagnosis. Here, we investigated the origin and functional consequence of the G6PC3 c.210delC variant found in patients of Mexican origin. Based on the shared haplotypes amongst carriers of the c.210delC mutation, we estimated that this variant originated from a founder effect in a common ancestor. Furthermore, by ancestry analysis, we concluded that it originated in the indigenous Mexican population. At the protein level, we showed that this frameshift mutation leads to an aberrant protein expression in overexpression and patient-derived cells. G6PC3 pathology is driven by the intracellular accumulation of the metabolite 1,5-anhydroglucitol-6-phosphate (1,5-AG6P) that inhibits glycolysis. We characterized how the variant c.210delC impacts glycolysis by performing extracellular flux assays on patient-derived cells. When treated with 1,5-anhydroglucitol (1,5-AG), the precursor to 1,5-AG6P, patient-derived cells exhibited markedly reduced engagement of glycolysis. Finally, we compared the clinical presentation of patients with the mutation c.210delC and all other G6PC3 deficient patients reported in the literature to date, and we found that c.210delC carriers display all prominent clinical features observed in prior G6PC3 deficient patients. In conclusion, G6PC3 c.210delC is a loss-of-function mutation that arose from a founder effect in the indigenous Mexican population. These findings may facilitate the diagnosis of additional patients in this geographical area. Moreover, the in vitro 1,5-AG-dependent functional assay used in our study could be employed to assess the pathogenicity of additional G6PC3 variants.

A Rare Coincidence of Three Inherited Diseases in a Family with Cardiomyopathy and Multiple Extracardiac Abnormalities.

A genetic diagnosis of primary cardiomyopathies can be a long-unmet need in patients with complex phenotypes. We investigated a three-generation family with cardiomyopathy and various extracardiac abnormalities that had long sought a precise diagnosis. The 41-year-old proband had hypertrophic cardiomyopathy (HCM), left ventricular noncompaction, myocardial fibrosis, arrhythmias, and a short stature. His sister showed HCM, myocardial hypertrabeculation and fibrosis, sensorineural deafness, and congenital genitourinary malformations. Their father had left ventricular hypertrophy (LVH). The proband's eldest daughter demonstrated developmental delay and seizures. We performed a clinical examination and whole-exome sequencing for all available family members. All patients with HCM/LVH shared a c.4411-2A>C variant in ALPK3, a recently known HCM-causative gene. Functional studies confirmed that this variant alters ALPK3 canonical splicing. Due to extracardiac symptoms in the female patients, we continued the search and found two additional single-gene disorders. The proband's sister had a p.Trp329Gly missense in GATA3, linked to hypoparathyroidism, sensorineural deafness, and renal dysplasia; his daughter had a p.Ser251del in WDR45, associated with beta-propeller protein-associated neurodegeneration. This unique case of three monogenic disorders in one family shows how a comprehensive approach with thorough phenotyping and extensive genetic testing of all symptomatic individuals provides precise diagnoses and appropriate follow-up, embodying the concept of personalized medicine. We also present the first example of a splicing functional study for ALPK3 and describe the genotype-phenotype correlations in cardiomyopathy.

Sex differences in treatment of familial hypercholesterolaemia: a meta-analysis.

Familial hypercholesterolaemia (FH) is a highly prevalent monogenic disorder characterized by elevated LDL cholesterol (LDL-C) levels and premature atherosclerotic cardiovascular disease. Sex disparities in diagnosis, lipid-lowering therapy, and achieved lipid levels have emerged worldwide, resulting in barriers to care in FH. A systematic review was performed to investigate sex-related disparities in treatment, response, and lipid target achievement in FH (PROSPERO, CRD42022353297). MEDLINE, Embase, The Cochrane library, PubMed, Scopus, PsycInfo, and grey literature databases were searched from inception to 26 April 2023. Records were eligible if they described sex differences in the treatment of adults with FH. Of 4432 publications reviewed, 133 met our eligibility criteria. In 16 interventional clinical trials (eight randomized and eight non-randomized; 1840 participants, 49.4% females), there were no differences between males and females in response to fixed doses of lipid-lowering therapy, suggesting that sex was not a determinant of response. Meta-analysis of 25 real-world observational studies (129 441 participants, 53.4% females) found that females were less likely to be on lipid-lowering therapy compared with males (odds ratio .74, 95% confidence interval .66-.85). Importantly, females were less likely to reach an LDL-C < 2.5 mmol/L (odds ratio .85, 95% confidence interval .74-.97). Similarly, treated LDL-C levels were higher in females. Despite this, male sex was associated with a two-fold greater relative risk of major adverse cardiovascular events including myocardial infarction, atherosclerotic cardiovascular disease, and cardiovascular mortality. Females with FH were less likely to be treated intensively and to reach guideline-recommended LDL-C targets. This sex bias represents a surmountable barrier to clinical care.

A New Case Series Suggests That SCA48 (ATX/STUB1) Is Primarily a Monogenic Disorder.

Monoallelic, pathogenic STUB1 variants cause autosomal dominant cerebellar ataxia (ATX-STUB1/SCA48). Recently, a genetic interaction between STUB1 variants and intermediate or high-normal CAG/CAA repeats in TBP was suggested, indicating digenic inheritance or a disease-modifying role for TBP expansions. To determine the presence and impact of intermediate or high-normal TBP expansions in ataxic patients with heterozygous STUB1 variants. We describe 21 patients with ataxia carrying a heterozygous STUB1 variant and determined TBP repeat length. A total of 15 of 21 patients (71%) carried a normal TBP<40 allele, 4 (19%) carried an intermediate TBP41-42 allele, and two carried a high-normal TBP40 allele (9.5%). Five of six carriers (83%) of both STUB1 variants and TBP40-42 alleles showed marked cognitive impairment. SCA48 is predominantly a monogenic disorder, because most patients carried an isolated, heterozygous STUB1 variant and presented with the typical combined phenotype of ataxia and cognitive dysfunction. Still, co-occurrence of TBP41-42 or high-normal TBP40 alleles was relatively frequent and associated with marked cognitive defects (28.5%), suggesting a modifying effect on clinical expression in some cases. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Kidney involvement in rare hereditary diseases

Various rare inherited disorders can be associated with kidney involvement, including glomerulopathies, tubulopathies, multiple cysts, congenital anomalies of the kidneys and urinary tract, urolithiasis, malignant and benign tumors. Genetic nephropathy should be always considered in children, adolescents and young patients with the kidneys or urinary tract disorders and/or patients with positive family anamnesis. Extrarenal manifestations can be a valuable clue for diagnosis of certain hereditary diseases, e.g. neurosensory deafness in Alport syndrome or photofobia in nephropathic cystinosis. Diagnosis of monogenic inherited diseases should be verified by genetic testing. Specific drugs are available for treatment of certain hereditary diseases involving kidney, e.g. Fabry disease, cystinosis, primary hyperoxaluria I type and atypical hemolytic uremic syndrome.

Utilizing adeno-associated virus as a vector in treating genetic disorders or human cancers.

Clinical data from over two decades, involving more than 3000 treated patients, demonstrate that adeno-associated virus (AAV) gene therapy is a safe, effective, and well-tolerated therapeutic method. Clinical trials using AAV-mediated gene delivery to accessible tissues have led to successful treatments for numerous monogenic disorders and advancements in tissue engineering. Although the US Food and Drug Administration (FDA) has approved AAV for clinical use, systemic administration remains a significant challenge. In this review, we delve into AAV biology, focusing on current manufacturing technologies and transgene engineering strategies. We examine the use of AAVs in ongoing clinical trials for ocular, neurological, and hematological disorders, as well as cancers. By discussing recent advancements and current challenges in the field, we aim to provide valuable insights for researchers and clinicians navigating the evolving landscape of AAV-based gene therapy.

Monogenic interferon-mediated diseases: novel phenotype and genotype characteristics from a Saudi population.

IFN-mediated diseases are mendelian innate immunodysregulatory disorders that present early in life with fevers, sterile organ inflammation, and a high type-I IFN-response gene signature in peripheral blood cells. To date, monumental discoveries of novel genetic variants with various phenotypic features have been recognised. We aimed to describe the genotype and phenotype findings in Saudi children diagnosed with autoinflammatory interferonopathy and to report novel findings. This is a descriptive retrospective cohort study of children with genetically confirmed type I interferonopathies. Medical records were reviewed for demographic, family history, clinical and laboratory data. All patients underwent genetic testing. A total of 20 patients (11 females) were included in the study. Sixteen patients (80%) presented within the first 2 years. The median age of disease onset was 0.87 years (IQR: 0.5-2) and the median age of diagnosis was 4.5 years (IQR: 2-7.5). The rates of consanguinity and family history of affected members were high (88% and 47%, respectively). Among the cohort of patients, whole exome sequencing was conducted for 15 patients. Three patients underwent targeted gene tests, and 2 patients had a leukoencephalopathy genetic panel. Eight patients were diagnosed with Aicardi-Goutières syndrome, attributed to variants in the RNASEH2A, RNASEH2C, and IFIH1 genes. Additionally, 2 patients were identified with STING-associated vasculopathy with onset in infancy linked to the TMEM173 variant. One patient exhibited chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature due to PSMB8, and another patient had DNase II. Moreover, 8 patients presented with rare interferonopathy conditions, including three with ISG15, 3 with ZNFX1, 1 with the SOCS1 variant, and 1 the STAT1 variant. Of 12 variants, six (50%) found to have novel genetic variants. The most frequent features were fever (75%), neurology (70%), mucocutaneous (60%), gastrointestinal (50%), and pulmonary (50%). Hypogammaglobinaemia and recurrent infections were seen in (45%) and (20%), respectively. Fifteen patients (75%) had elevated inflammatory markers. The majority of patients received intensive treatment, including corticosteroids, JAK inhibitors, IVIG, and various immunosuppressive agents. Despite these interventions, a partial response to treatment was observed, and cumulative disease damage primarily manifested as growth failure and developmental delay. Our findings support the previous reports; early-onset fever, neurology, and respiratory features should raise the suspicion of interferonopathies. However, there is eminent evidence of phenotypic variability. Our data also expanded the spectrum of clinical findings in relation to novel genetic variants.

Human life within a narrow range: The lethal ups and downs of type I interferons.

The past 20 years have seen the definition of human monogenic disorders and their autoimmune phenocopies underlying either defective or enhanced type I interferon (IFN) activity. These disorders delineate the impact of type I IFNs in natural conditions and demonstrate that only a narrow window of type I IFN activity is beneficial. Insufficient type I IFN predisposes humans to life-threatening viral diseases (albeit unexpectedly few) with a central role in immunity to respiratory and cerebral viral infection. Excessive type I IFN, perhaps counterintuitively, appears to underlie a greater number of autoinflammatory and/or autoimmune conditions known as type I interferonopathies, whose study has revealed multiple molecular programs involved in the induction of type I IFN signaling. These observations suggest that the manipulation of type I IFN activity to within a physiological range may be clinically relevant for the prevention and treatment of viral and inflammatory diseases.

Clinical and genetic characteristics of congenital hyperinsulinism in Norway: A nationwide cohort study.

Congenital hyperinsulinism (CHI) is a rare, monogenic disease characterized by excessive insulin secretion. We aimed to evaluate all probands with suspected CHI in Norway registered over the past two decades. The study included 98 probands. Clinical data were cumulated from medical records. All probands were screened for variants in the genes ABCC8 and KCNJ11. Other CHI-related genes were Sanger-sequenced as indicated by the patients' phenotype (N=75) or analyzed by next-generation sequencing employing a panel of 30 CHI-related genes (N=23). Twenty-one probands (21%) received a diagnosis other than CHI, the most common being idiopathic ketotic hypoglycemia (9%) or syndromic hyperinsulinism (4%). In the final cohort of 77 CHI probands, genetic findings were revealed in 46 (60%). ABCC8 variants were most common (N=40) and five novel variants were identified. One proband harbored both the pathogenic GCK variant p.(Ala456Val) and the ABCC8 variant p.(Gly505Cys). Although most ABCC8 variants caused immediate disease onset with severe hypoglycemia and were diazoxide-unresponsive, eight probands had a heterozygous, apparently dominant variant with milder phenotype. Two probands had pathogenic variants in GLUD1, whereas variants in HADH, HNF4A, KCNJ11, and HK1 were identified in one proband each, the latter being non-coding. Neurologic sequelae were reported in 53% of the CHI probands. Of non-surgically treated probands, 43% had spontaneous resolution. The minimum birth prevalence of CHI in Norway is 1:19,400 live births. Individuals with disease-causing ABCC8 variants dominated our cohort. Patients with known genetic etiology had earlier and more severe disease-onset than genetically unsolved patients.

P-540 Strategic implementation of PGT-M for multiple genes post qhole exome sequencing in couples with familial history: a comprehensive study

Abstract Study question What advantages does Whole Exome Sequencing offer to couples with a familial history of hereditary disorders? Summary answer WES offers a comprehensive risk assessment, facilitating the development of an effective PGT-M for Multiple Genes in the prevention of severe diseases in their offspring What is known already PGT-M enables the transfer of unaffected embryos to couples at risk of transmitting monogenic disorders. With the advancements in technologies like Whole Exome Sequencing (WES) and Whole Genome Sequencing (WGS) identifying causal mutations, there is a growing demand for PGT-M applications that concurrently assess multiple genetic disorders. This is particularly crucial, as families initially referred for one condition may later be discovered to be at risk for additional monogenic disorders due to the common carriership status of the couples. Study design, size, duration This is a retrospective study including couples with previous familial history of genetic disorders referred to a single genetic unit between years 2020-2024. Either WES-DUO or WES-TRIO analysis were performed in the absence or presence of an affected child, respectively. Participants/materials, setting, methods WES-DUO or WES-Trio analyses were performed on 94 couples with a familial history of genetic diseases encompassing diverse medical domains. Around 50% of the couples exhibited consanguinity. Utilizing the Novaseq 6000 next-generation sequencing platform, exonic regions were sequenced with an average coverage of 100X. Bioinformatic analysis followed the manufacturer’s recommended workflow, and variant analysis adhered to ACMG criteria, ClinVar, and HGMD. Segregation analysis was conducted through Sanger sequencing using region-specific primers. Main results and the role of chance WES, followed by segregation analysis, pinpointed reportable pathogenic or likely pathogenic variants in 46 out of 94 families as the root cause of the referral condition. Interestingly, 42 of these families exhibited at least one additional common gene mutation in both partners. Notably, among the 27 families with confirmed diagnoses, in vitro fertilization (IVF) and preimplantation genetic testing for monogenic disorders (PGT-M) were undertaken. Within this cohort, PGT-M for multiple genes was successfully conducted in 22 families, 96 embryos were found to be transferable resulting in the birth of healthy infants. Limitations, reasons for caution The overall diagnostic confirmation rate of WES analysis reached 48.9%. A quite high diagnostic yield achieved in this study is notably influenced by the substantial prevalence of consanguineous cases. Wider implications of the findings This study highlights the need for implementing PGT-M for multiple genes. Failure to undergo such testing would potentially lead to the birth of children affected by other conditions.This study also underscores the efficiency of encompassing WES, mutation confirmation, segregation analysis, bioinformatic processing and PGT applications in a single genetic unit. Trial registration number none

P-710 Comparison of cumulative delivery rates per aspiration cycle in patients fulfilling Bologna and POSEIDON criteria

Abstract Study question Do cumulative delivery rates (CDRs) per aspiration cycle differ in low-prognosis patients according to the Bologna and POSEIDON (Patient-Oriented-Strategies-Encompassing IndividualizeD-Oocyte-Number) classification criteria? Summary answer The CDR was 8.7% in Bologna and 22.7% in POSEIDON. The odds of achieving live-birth were ∼3-fold higher in POSEIDON than in the Bologna group. What is known already Bologna criteria were generated to address the heterogeneity in the definition of the Poor Ovarian Response (POR). However, patients meeting these criteria may not be homogeneous in terms of the number of oocytes retrieved and live birth rate. Subsequently, as a more inclusive classification, the POSEIDON criteria were proposed to stratify low-prognosis patients according to female age and suboptimal response to ovarian stimulation. To our knowledge, there is a paucity of data comparing CDRs between the POSEIDON and Bologna groups. Study design, size, duration Retrospective cohort study including 1250 patients undergoing their first ovarian egg retrieval cycle at Hacettepe University IVF Center in Ankara between 2017 and 2023. Exclusion criteria were female age &amp;gt;45 years old, body mass index &amp;gt;35 kg/m2, azoospermia, pre-implantation genetic testing (PGT) for structural rearrangement or monogenic disorders, fertility preservation cycles, dual-stimulation cycles, premature ovarian insufficiency, and hypogonadotropic hypogonadism. The primary outcome measured was CDR defined by ICMART (International Committee for Monitoring Assisted Reproductive Technologies). Participants/materials, setting, methods The Bologna patients have at least two of the following three features; female-age ≥40 or prior ovarian surgery, AMH&amp;lt;1.1ng/ml or antral-follicle-count (AFC)&amp;lt;5-7, and obtaining ≤3 oocytes in prior conventional stimulation. POSEIDON patients were categorized into four groups; younger(&amp;lt;35) and older(≥35) women with AMH≥1.2/AFC≥5 experiencing an unexpected poor(&amp;lt;4 oocytes-retrieved) or suboptimal(4–9 oocytes-retrieved) response, along with respective younger and older counterparts with AMH&amp;lt;1.1/AFC&amp;lt;5. Non-POSEIDON patients were those with AMH≥1.2/AFC≥5 and &amp;gt;9 oocytes-retrieved. General-Estimated-Equation(GEE) analysis was employed. Main results and the role of chance Out of 1250 patients, 79.6% were classified as POSEIDON, with sub-groups as follows: 5.28% Group 1a, 23.4% Group 1b, 3.6% Group 2a, 10.1% Group 2b, 14.64% Group 3, and 22.48% Group 4. The number of patients meeting Bologna criteria was 17.4% (218). For POSEIDON patients, median[IQR] values were: age 34 [30-38], AMH 1.33 [0.65-2.69], oocytes retrieved 4 [2-6], and embryo transfers 1 [1-2]. For non-POSEIDON patients: age 30 [27-33], AMH 4.63 [2.93-7.07], oocytes retrieved 13 [11-15], and embryo transfers 2 [1-3]. In Bologna patients: age 40 [36-42], AMH 0.46 [0.20-0.76], oocytes retrieved 2 [1-3], and embryo transfers 1 [0-1]. For non-Bologna patients: age 31 [28-36], AMH 2.30 [1.17-4.29], oocytes retrieved 6 [3-9], and embryo transfers 1 [1-2]. CDR for non-POSEIDON: 49.8%; Group 1a, 24.2%; Group 1b, 34.1%; Group 2a, 15.6%; Group 2b, 27.6%; Group 3, 20.8%; Group 4, 10.7%. In clustered-GEE analysis, using non-POSEIDON as reference, odds ratios (ORs) for live birth were: Group 1a OR 0.32 [0.18 - 0.60]; Group 1b OR 0.52 [0.37-0.74]; Group 2a OR 0.19 [0.08-0.43]; Group 2b OR 0.38 [0.24-0.61]; Group 3 OR 0.26 [0.17-0.41]; Group 4 OR 0.12 [0.08-0.19]. CDR for the Bologna group: 8.7% (OR: 0.10, 0.06-0.16); non-Bologna patients: 32.4% [OR: 0.48, 0.39-0.60]. Limitations, reasons for caution The limitations of the study encompass its retrospective cohort design and the variability introduced by different individuals conducting antral follicle counts using 2D ultrasonography. Wider implications of the findings Significant CDR differences exist between Bologna and Poseidon groups. POSEIDON patients show ∼2-fold lower CDR than normal responders, and Bologna patients exhibit ∼4-fold lower CDR than non-Bologna patients. Poseidon criteria cover a broader range of low-prognosis patients, while meeting Bologna criteria indicates a narrower, more specific group with poorer outcomes. Trial registration number N/A