Linkage Analysis Research Articles

Mapping and Functional Dissection of the Rumpless Trait in Piao Chicken Identifies a Causal Loss of Function Mutation in the Novel Gene Rum.

Rumpless chickens exhibit an abnormality in their tail development. The genetics and biology of this trait has been studied for decades to illustrate a broad variation in both the types of inheritance and the severity in the developmental defects of the tail. In this study, we created a backcross pedigree by intercrossing Piao (rumpless) with Xianju (normal) to investigate the genetic mechanisms and molecular basis of the rumpless trait in Piao chicken. Through genome-wide association and linkage analyses, the candidate region was fine-mapped to 798.5 kb (chromosome 2: 86.9 to 87.7 Mb). Whole-genome sequencing analyses identified a single variant, a 4.2 kb deletion, which was completely associated with the rumpless phenotype. Explorations of the expression data identified a novel causative gene, Rum, that produced a long, intronless transcript across the deletion. The expression of Rum is embryo-specific, and it regulates the expression of MSGN1, a key factor in regulating T-box transcription factors required for mesoderm formation and differentiation. These results provide genetic and molecular experimental evidence for a novel mechanism regulating tail development in chicken and report the likely causal mutation for the tail abnormity in the Piao chicken. The novel regulatory gene, Rum, will, due to its role in fundamental embryo development, be of interest for further explorations of a potential role in tail and skeletal development also in other vertebrates.

Linkage analysis of factors influencing the sustainability of Lake Singkarak in West Sumatra Province, Indonesia

Lake Singkarak, located in the West Sumatra Province, resulted from a tectonic process affected by the Great Sumatran Fault. The lake has a total area of 107 km2 and is used for fisheries, tourism, hydroelectric power plant, etc. However, this lake is facing an array of issues and is even considered in a critical condition. Population growth, land use changes, agriculture development, and climate change are suspected to be the causes. It was also aggravated by the COVID-19 pandemic, wherein lake maintenance was neglected. The lake is a system, therefore maintenance of the lake cannot be performed partially and sporadically but must be integrated and comprehensive. This research analyses factors affecting the lake’s sustainability and the linkage between those factors. This research employed a system thinking approach. There are direct and indirect links between social, economic, and environmental factors, as illustrated in a Causal Loop Diagram. This diagram depicts how economic activities are constrained by available potential, which, at certain thresholds, may result in a drop in lake quality if managed in an unsustainable manner. Additionally, lake management appears to be an important factor in overcoming existing issues and establishing a sustainable lake.

Prenatal diagnosis of 1408 foetuses at risk of DMD/BMD by MLPA and Sanger sequencing combined with STR linkage analysis

ObjectiveThis study is a retrospective analysis of the prenatal genetic diagnosis results of 1408 foetuses at high risk of DMD/BMD to provide information for clinical genetic counselling.BackgroundDuchenne muscular dystrophy (DMD) is a severe neuromuscular disorder characterized by skeletal and cardiac muscle weakness. With the deepening of disease research, some treatments have been applied in clinics. Therefore, early and accurate prenatal diagnosis can inform pregnancy choices for high-risk families.MethodsA total of 1316 unrelated DMD/BMD families with confirmed genetic diagnoses were recruited from the Genetic and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University. Prenatal diagnosis of 1408 high-risk foetuses was performed by MLPA and Sanger sequencing combined with STR linkage analysis for all families.ResultsAmong the 1316 families, large deletions, duplications, and small variants of the DMD gene accounted for 70.4% (927/1316), 8.2% (108/1316), and 21.4% (281/1316), respectively. Among 1316 mothers, 863 (65.6%) were carriers, and 453 (34.4%) were not carriers. The rate of de novo variants was 34.4% (453/1316) in our study. In addition, gonadal mosaicism was observed in 11 pregnant females. Prenatal diagnosis was provided for 1408 high-risk foetuses; 282 foetuses were identified as male patients, 219 foetuses were female carriers, and the remainder had normal genetics. The results of prenatal diagnosis were consistent with the results of follow-up.ConclusionsAccurate and rapid prenatal diagnosis can be achieved using MLPA, Sanger sequencing, and STR linkage analysis. Furthermore, germline mosaicism in DMD should not be ignored; considering this, a prenatal diagnosis for all pregnant women with a family history of DMD/BMD regardless of whether they carried disease-causing variants is proposed. Genetic counselling and targeted prenatal diagnosis will continue to be a cornerstone of DMD/BMD family management in the future.

ApoE variant associated with cognitive resilience alters AD associated hyperexcitability in dentate granule neurons

AbstractBackgroundCognitive decline in Alzheimer’s disease (AD) differs based on background genetics even with similar pathology. Using genetic linkage analysis, we identified a coding variant in the receptor binding domain of ApoE that leads to changes in cognitive performance across a genetically diverse population harboring familial (FAD) mutations known as the AD‐BXDs (Neuner et al., 2019). Using CRISPR‐based gene editing, we developed a C57BL/6J (B6) mouse carrying the ApoE allele from the DBA/2J (D2) strain (ApoEE163D) and determined that ApoEE163D mice with 5XFAD transgene (ApoEE163D‐5XFAD) are susceptible to cognitive decline compared to B6‐5XFAD mice (Kaczorowski, et al., 2022).Analysis of hippocampal RNA sequencing profiles from the hippocampus indicates robust transcriptomic changes in dentate gyrus (DG) granule cells associated with cognitive resilience to FAD mutations in the presence of the B6 ApoE genotype. Here we aim to evaluate the functional implications.MethodWe adapted the Patch‐Seq method (Cadwell et al., 2017) to investigate transcriptional and electrophysiological changes within the DG associated with both FAD mutations and ApoE genotype. Whole‐cell patch clamp was used to evaluate intrinsic excitability of granule cells from 14month old B6 mice carrying FAD mutations and ApoEE163D, compared to age matched controls. The cellular contents, including the nucleus, were collected after each recording to characterize the transcriptome, and the cells were filled and stained for downstream analysis of neuronal morphology.ResultWe observed a significant interaction of the 5XFAD and ApoE genotypes on DG granule cell excitability. Specifically, cells from ApoEE163D‐5XFAD required less current stimulus to both elicit a single action potential, and to fire in response to a current ramp (rheobase). Although input resistance was comparable across all 4 groups, the sag ratio of ApoEE163D‐5XFAD was also reduced.ConclusionEnhancement of DG excitability of ApoEE163D‐5XFAD mice may underlie increased seizure susceptibility that has been reported previously in FAD animal models on D2 genetic background and associated with increased risk of seizures in AD patients. Ongoing work will integrate DG excitability with single‐cell RNAseq, morphology, and behavior to dissect mechanisms underlying the modifier effect of ApoE genotype on susceptibility and resilience to cognitive deficits in FAD mutation carriers.

#152 : Exploring the Limitations of Linkage-Only PGT-M

Background and Aims: Although PGT-M cases can be conducted using linkage only, the inclusion of a direct test targeting the relevant genetic variants should be fundamental to best practise. We present four cases illustrating the limitations of linkage only PGT-M. Methods: Three cases used STRs for linkage analysis and the fourth Illumina Infinium Karyomapping. Direct variant detection encompassed Sanger sequencing, STRs and/or fragment PCR. Results: Case 1 Osteoporosis-pseudoglioma syndrome Sanger sequencing for LRP5c.3107G[Formula: see text]A and LRP5c.4487C[Formula: see text]A were critical for identifying a recombination in the familial control and subsequent correct assignment of STR phasing. Case 2 Osteogenesis imperfecta type I SNP-based linkage identified a recombinant embryo. Sanger sequencing for COL1A1c.2461G[Formula: see text]A resolved an unknown status to affected. Case 3 Neurofibromatosis type II Variant detection in this de novo mosaic case used two STRs within the NF2 exon2-11del to establish low- and high-risk linkage patterns. Two tumour samples with different second hit mutations exhibited reduced signal intensity for one allele. This was consistent with the presence of a weaker deleted allele due to sample contamination with non-tumour cells. Four of nine embryos contained two alleles within the minimum deletion and were first choice for transfer, resulting in an NAD prenatal confirmation and healthy liveborn. Case 4 Neurofibromatosis type I A de novo mosaic case required reverse linkage by means of a direct assay for the NF1c.1445_1446insCC variant. Affected embryos were subsequently used to phase flanking STRs and obtain linkage, resulting in one liveborn and one ongoing pregnancy. Conclusions: When a direct test is not included in PGT-M, a family may not be able to be offered a test, or misdiagnosis risk may increase. For de novo, mosaic and cases with suspected recombination in a reference sample, analysis of multiple cycles and/or the inclusion of non-clinical embryos to increase sample numbers improves accuracy of testing.

RELATIONSHIP OF THE MINING SECTOR TO THE ELECTRICITY AND GAS PROCUREMENT SECTOR IN WEST PAPUA PROVINCE USING INPUT OUTPUT ANALYSIS

Linkage analysis is a method used to understand the economic structure of a region. This analysis can also be used to figure out how much influence a sector has on other sectors based on the input and output tables for each sector. This research was conducted to analyze the forward and backward linkages of the mining and quarrying sector to the electricity and gas procurement sector in West Papua Province, both directly and indirectly. The data used in this research is sourced from the West Papua Province Input Output Table Domestic Transactions Based on Producer Prices 2016 Updated 2021. The method used in this research is a descriptive quantitative method. From the results of this research, it was found that the value of backward linkages in the mining and quarrying sector was more significant than the value of forward linkages, both directly and indirectly, to the electricity and gas procurement sector. Thus, the mining and quarrying sector requires more output from the electricity and gas procurement sector as input, compared to the electricity and gas procurement sector's need for the output of the mining and quarrying sector.

농업용 저수지 조기경보시스템 현황 분석 및 개선방안

Of the 17,160 agricultural reservoirs nationwide, 96% are aged more than 30 years after construction. Aging reservoirs are at risk of deterioration and potential collapse. The torrential rains between July and August 2020 caused 26 collapse and loss filure across the country. Preemptive and comprehensive response plan is needed to prevent damage to life and property caused by such a reservoir collapse, and this study analyzes the early warning system of agricultural reservoirs as part of a preemptive and comprehensive countermeasure plan to diagnose the current situation and come up with improvement measures. Using bathymetric data, real-time water level change through water level-rainfall linkage analysis and early warning standard setting according to rainfall were proposed. Using bathymetric and aerial survey data, a three-dimensional reservoir collapse simulation was used to predict the arrival time and submerged range of the collapsed flow, suggesting early warning standards and positioning methods.

Quantitative Trait Loci Mapping Identified Candidate Genes Involved in Plant Height Regulation in Rice

Rice plant height is an agricultural trait closely related to biomass, lodging tolerance, and yield. Identifying quantitative trait loci (QTL) regions related to plant height regulation and developing strategies to screen potential candidate genes can improve agricultural traits in rice. In this study, a double haploid population (CNDH), derived by crossing ‘Cheongcheong’ and ‘Nagdong’ individuals, was used, and a genetic map was constructed with 222 single-sequence repeat markers. In the RM3482-RM212 region on chromosome 1, qPh1, qPh1-1, qPh1-3, qPh1-5, and qPh1-6 were identified for five consecutive years. The phenotypic variance explained ranged from 9.3% to 13.1%, and the LOD score ranged between 3.6 and 17.6. OsPHq1, a candidate gene related to plant height regulation, was screened in RM3482-RM212. OsPHq1 is an ortholog of gibberellin 20 oxidase 2, and its haplotype was distinguished by nine SNPs. Plants were divided into two groups based on their height, and tall and short plants were distinguished and clustered according to the expression level of OsPHq1. QTLs and candidate genes related to plant height regulation, and thus, biomass regulation, were screened and identified in this study, but the molecular mechanism of the regulation remains poorly known. The information obtained in this study will help develop molecular markers for marker-assisted selection and breeding through rice plant height control.

Integrating Communication Science and Computational Methods to Study Content-Based Social Media Effects

ABSTRACT A pressing societal and scientific question is how social media use affects our cognitions, emotions, and behaviors. To answer this question, fine-grained insight into the content of individuals’ social media use is needed. It is difficult to study content-based social media effects with traditional survey methods because such methods are incapable of capturing the extreme volume and variety of social media content that is shared and received. Therefore, this special issue aims to illustrate how content-based social media effects could be examined by integrating communication sciences and computational methods. We describe a three-step method to investigate content-based media effects, which involves (a) collecting digital trace data, (b) performing automated textual and visual content analysis, and (c) conducting linkage analysis. This Special Issue zooms in on these steps and describes the strengths and weaknesses of different computational methods. We conclude with some challenges that need to be addressed in future research.

Soybean Variety Saedanbaek Confers a New Resistance Allele to Phytophthora sojae

Phytophthora root and stem rot (PRSR) disease results in substantial losses in soybean production worldwide. The occurrence of PRSR caused by Phytophthora sojae Kaufmann & Gerdemann has become increasingly important for soybean production in the Republic of Korea, but domestic soybean–P. sojae interaction has been less studied. The disease has been managed by developing varieties harboring resistance to the Phytophthora sojae (Rps) gene. The present study aimed to identify a major gene locus conferring resistance to new P. sojae isolate 2858 in the recombinant inbred line population derived from a cross between parental lines ‘Daepung’ (susceptible) and ‘Saedanbaek’ (resistant). Seventy-three recombination inbred lines (RILs) were evaluated for resistance to P. sojae isolate 2858. A resistance locus was identified in the approximate 3.3–4.3 megabase pair region on chromosome 3 using both single-marker and linkage analyses. The Rps of Saedanbaek (RpsSDB) was located on the well-known Rps gene/allele cluster region, which also partially overlapped with a locus previously identified in the Korean soybean variety, ‘Daewon’, resistant to another P. sojae isolate 2457 (RpsDW). Approximately 402 kilobase pairs of the interval region overlapped, including six nucleotide-binding site-leucine-rich repeat (NBS-LRR)-coding genes. Additional phenotypic assays revealed that Saedanbaek was susceptible to isolate 2457 and that Daewon was susceptible to isolate 2858, indicating that RpsSDB and RpsDW are different genes or alleles that confer race-specific resistance to the two P. sojae isolates. These results provide information that will be helpful for breeders developing P. sojae-resistant cultivars.

A 1-bp deletion in the MC04g1399 is highly associated with failure to produce fruit wart in bitter gourd (Momordica charantia L.)

Fruit wart is an important appearance trait influencing consumer preferences of bitter gourd. The molecular genetic mechanisms underlying fruit wart formation in bitter gourd are largely unknown. In this study, genetic analysis based on four generations showed that fruit wart formation in bitter gourd was controlled by a single dominant locus named as Fwa. The Fwa locus was initially mapped into a 4.82 Mb region on pseudochromosome 4 by BSA-seq analysis and subsequently narrowed down to a 286.30 kb region by linkage analysis. A large F2 population consisting of 2 360 individuals was used to screen recombinants, and the Fwa locus was finally fine mapped into a 22.70 kb region harboring four protein-coding genes through recombination analysis. MC04g1399, encoding an epidermal patterning factor 2-like protein, was proposed as the best candidate gene for Fwa via sequence variation and expression analysis. In addition, a 1-bp insertion and deletion (InDel) variation within MC04g1399 was converted to a cleaved amplified polymorphic sequence (CAPS) marker that could precisely distinguish between the warty and non-warty types with an accuracy rate of 100 % among a wide panel of 126 bitter gourd germplasm resources. Our results not only provide a scientific basis for deciphering the molecular mechanisms underlying fruit wart formation but also provide a powerful tool for efficient genetic improvement of fruit wart via marker-assisted selection.

Combined linkage analysis and association mapping identifies genomic regions associated with yield-related and drought-tolerance traits in wheat (Triticum aestivum L.).

Combined linkage analysis and association mapping identified genomic regions associated with yield and drought tolerance, providing information to assist breeding for high yield and drought tolerance in wheat. Wheat (Triticum aestivum L.) is one of the most widely grown food crops and provides adequate amounts of protein to support human health. Drought stress is the most important abiotic stress constraining yield during the flowering and grain development periods. Precise targeting of genomic regions underlying yield- and drought tolerance-responsive traits would assist in breeding programs. In this study, two water treatments (well-watered, WW, and rain-fed water stress, WS) were applied, and five yield-related agronomic traits (plant height, PH; spike length, SL; spikelet number per spike, SNPS; kernel number per spike, KNPS; thousand kernel weight, TKW) and drought response values (DRVs) were used to characterize the drought sensitivity of each accession. Association mapping was performed on an association panel of 304 accessions, and linkage analysis was applied to a doubled haploid (DH) population of 152 lines. Eleven co-localized genomic regions associated with yield traits and DRV were identified in both populations. Many previously cloned key genes were located in these regions. In particular, a TKW-associated region on chromosome 2D was identified using both association mapping and linkage analysis and a key candidate gene, TraesCS2D02G142500, was detected based on gene annotation and differences in expression levels. Exonic SNPs were analyzed by sequencing the full length of TraesCS2D02G142500 in the association panel, and a rare haplotype, Hap-2, which reduced TKW to a lesser extent than Hap-1 under drought stress, and the Hap-2 varieties presented drought-insensitive. Altogether, this study provides fundamental insights into molecular targets for high yield and drought tolerance in wheat.

Relationships and Interdependencies of the Agri-Food Sector in a Regional Economy: Employing an Input-Output Model

The agri-food sector has been stressed as an essential determinant for an economy, as its impacts contribute directly and indirectly to its growth in various ways; with its products, with its trade, both in outputs and inputs, and when the sector grows. The current work aims to capture the relationships and impacts of the agri-food sector in a regional economy through linkage analysis. Building upon the relationship marketing theory, this is achieved by utilizing an I/O model constructed through modifying the Generation of Regional Input-Output Tables (GRIT) regionalization technique and using the Flegg Location Quotient (FLQ). The relationships of the economic sectors resulting from the purchases and sales between them provide helpful information for the region’s economy. The results demonstrate that the agri-food-related sectors are closely linked in the regional economy, as the primary activities supply processing with raw inputs. Moreover, agri-food-related sectors have strong interconnections with the rest of the local economy and can induce economy-wide impacts. Accordingly, the interdependence between different economic sectors determines the agri-food sector’s economic impact.

An affordable and convenient diagnostic marker to identify male and female hop plants.

Hop production utilizes exclusively female plants, whereas male plants only serve to generate novel variation within breeding programs through crossing. Currently, hop lacks a rapid and accurate diagnostic marker to determine whether plants are male or female. Without a diagnostic marker, breeding programs may take 1-2 years to determine the sex of new seedlings. Previous research on sex-linked markers was restricted to specific populations or breeding programs and therefore had limited transferability or suffered from low scalability. A large collection of 765 hop genotypes with known sex phenotypes, genotyping-by-sequencing, and genome-wide association mapping revealed a highly significant marker on the sex chromosome (LOD score = 208.7) that predicted sex within our population with 96.2% accuracy. In this study, we developed a PCR allele competitive extension (PACE) assay for the diagnostic SNP and tested three quick DNA extraction methodologies for rapid, high-throughput genotyping. Additionally, the marker was validated in a separate population of 94 individuals from 15 families from the USDA-ARS hop breeding program in Prosser, WA with 96% accuracy. This diagnostic marker is located in a gene predicted to encode the basic helix-loop-helix transcription factor protein, a family of proteins that have been previously implicated in male sterility in a variety of plant species, which may indicate a role in determining hop sex. The marker is diagnostic, accurate, affordable, and highly scalable and has the potential to improve efficiency in hop breeding.

Identification of a Novel Pm65 Allele Conferring a Wide Spectrum of Resistance to Powdery Mildew in Wheat Accession PI 351817.

Powdery mildew is caused by the highly adaptive biotrophic fungus Blumeria graminis f. sp. tritici infecting wheat worldwide. Novel powdery mildew resistance genes are urgently needed that can be used rapidly in wheat cultivar development with minimal disruption of trait advances elsewhere. PI 351817 is a German cultivar exhibiting a wide spectrum of resistance to B. graminis f. sp. tritici isolates collected from different wheat-growing regions of the United States. Evaluation of an F2 population and 237 F2:3 lines derived from OK1059060-2C14 × PI 351817 for responses to B. graminis f. sp. tritici isolate OKS(14)-B-3-1 identified a single dominant gene, designated Pm351817, for powdery mildew resistance in PI 351817. Using bulked segregant analysis (BSA) and simple sequence repeat (SSR) markers, Pm351817 was mapped in the terminal region of the long arm of chromosome 2A. Deep sequencing of the genotyping-by-sequencing libraries of the two parental lines identified a set of single-nucleotide polymorphism (SNP) markers in the 2AL candidate gene region. Those SNP markers was subsequently converted to Kompetitive allele-specific PCR (KASP) markers for genotyping the mapping population. Linkage analysis delimited Pm351817 to a 634-kb interval between Stars-KASP656 (771,207,512 bp) and Stars-KASP662 (771,841,609 bp) on 2AL, based on the Chinese Spring reference sequence IWGSC RefSeq v 2.1. Tests of allelism indicated that Pm351817 is located at the Pm65 locus. Pm351817 shows resistance to all B. graminis f. sp. tritici isolates used in this study and can be used to enhance powdery mildew resistance in the United States. KASP markers flanking Pm351817 can be used to select Pm351817 in wheat breeding programs after further tests for polymorphism.

Genome‐wide association analysis of coleoptile length and interaction with plant height in durum wheat

AbstractGenotypes with longer coleoptiles can be sown in deep soil layers to reach the underground moisture needed for germination in dry areas. Developing new varieties with longer coleoptiles and shorter plant heights would be novel for wheat breeding and production. In this study, coleoptile lengths of a panel of durum wheat (Triticum turgidum ssp. durum) genotypes were determined, and 14,255 DArTseq (SNP and Silico‐DArT) markers were used to identify coleoptile length‐associated markers by genome‐wide association study (GWAS). A wide genetic variation was accounted for both coleoptile length and plant height. The genetic relationships between coleoptile length and plant height were evaluated using plant height values from five different environments. Two environmentally stable MTAs were identified, one for coleoptile length (QCol.su.4BS) and one for plant height (QPh.su.4BS). These MTAs were located on the short arm of chromosome 4B, with LOD scores up to 12.00 and 17.00, respectively. A relatively high LD (r2 = 0.71) was accounted for between QCol.su.4BS and QPh.su.4BS. The LD block intervals of the MTAs overlapped with some genes with roles in plant growth and development. The functions of plausible candidate genes tell us that QCol.su.4BS may be controlling coleoptile length, whereas QPh.su.4BS may be regulating plant height. The combination of the two loci would be desirable. In conclusion, this study sheds light on the genetic control of coleoptile length and its relationship with plant height in durum wheat.

The Mining of Genetic Loci and the Analysis of Candidate Genes to Identify the Physical and Chemical Markers of Anti-Senescence in Rice.

Premature senescence is a common occurrence in rice production, and seriously affects rice plants' nutrient utilization and growth. A total of 120 recombinant inbred lines (RILs) were obtained from successive self-crossing of F12 generations derived from Huazhan and Nekken2. The superoxide dismutase (SOD) activity, malondialdehyde (MDA), content and catalase (CAT) activity related to the anti-senescence traits and enzyme activity index of rice were measured for QTL mapping using 4858 SNPs. Thirteen QTLs related to anti-senescence were found, among which the highest LOD score was 5.70. Eighteen anti-senescence-related genes were found in these regions, and ten of them differed significantly between the parents. It was inferred that LOC_Os01g61500, LOC_Os01g61810, and LOC_Os04g40130 became involved in the regulation of the anti-senescence molecular network upon upregulation of their expression levels. The identified anti-senescence-related QTLs and candidate genes provide a genetic basis for further research on the mechanism of the molecular network that regulates premature senescence.

In search of genetic modifiers that explain the phenotypic variability in SMAD3-related aortopathy

Abstract Introduction Loeys-Dietz Syndrome (LDS) is an autosomal dominant connective tissue disorder presenting with thoracic aortic aneurysm and dissection (TAAD). Remarkably, some LDS patients remain cardiovascularly unaffected throughout life, while others carrying the exact same genetic variant die early because of an aortic dissection. We hypothesize that genetic modifiers are the basis of this observation. Objectives Identify genetic modifiers that explain the variability in LDS-related aortopathy. Generate a patient-specific iPSC-vascular smooth muscle cell (VSMC) model to allow functional validation of genetic modifiers. Material and Methods We have access to a large LDS family segregating a pathogenic SMAD3 (p.Arg287Gln) variant. Identification of candidate modifiers in this family encompasses genome-wide SNP-based linkage analysis (n=19, available mutation carriers) and WGS (3 affected (AMC) and 4 unaffected mutation carriers (UMC)). Subsequent functional validation involves CRISPR/Cas-based modifier correction in iPSC-VSMCs of an affected variant carrier, which are created using the CytoTune iPS 2.0 Kit and the Granata et al. VSMC differentiation protocols. Results Linkage analysis suggests the presence of an aggravating modifier at chr2 (LOD: 2.68). The region of 6 Mb contains 19 protein coding genes of which the TNFAIP6 gene was ToppGene prioritized. There were no exonic variants in any of the genes that segregate with affection status at MAF 0.01%. However, we are currently adapting the the filtering strategy and will look into more common variants, MAF 10% for exonic and MAF 5% for intronic variants. iPSCs of an AMC and its isogenic control were created. They express core pluripotency markers and possess trilineage differentiation potential in the absence of the Sendai vectors. SNP array confirmed the genomic stability and identity of the cells. Conclusion and Future Work The obtained data suggest the presence of an aggravating modifier at chr2. Further analyses are ongoing to pinpoint the exact modifier variant explaining the linkage signal. Subsequently, the identified modifier(s) will be modelled in an in-vitro created iPSC-VSMC model.

Cardiac rehabilitation reduces risk of overall mortality within 12 months after a heart failure hospitalization: data linkage analysis of 9,023 patients in Australia

Abstract Background Meta-analyses of randomized trials show that cardiac rehabilitation (CR) prevents cardiovascular (CV) and heart failure (HF)-specific hospitalizations. However, globally only 30-50% of eligible patients participate in CR which might affect CR effectiveness. Purpose To investigate CR utilization and clinical outcomes after an admission for HF. Methods This is a retrospective cohort study of patients >=18 years old discharged from public hospitals in South Australia with a diagnosis of HF from 2016-2021. We linked the statewide clinical CR database to hospital administrative and death databases to assess CR utilization (non-attendance vs attendance without completion vs completion of >= 70% of the sessions), the composite primary outcome (CV re-admission or CV death within 12 months after the index hospitalization) and the secondary outcome (all-cause death within 12 months after the index hospitalization). To investigate factors associated with not attending CR, we adjusted a logistic model by age, sex, Index of Relative Socioeconomic Advantage and Disadvantage (IRSAD), remoteness; admission during the COVID pandemic, acute myocardial infarction (MI), procedures, arrhythmias, Charlson comorbidities index, history of diabetes, hypertension, obesity, prior stroke, and peripheral vascular disease. To investigate the association of the primary and secondary outcomes with CR utilization, we adjusted Cox survival models by age; sex; IRSAD; remoteness; ACS; revascularization, valve and implantable devices procedures; AF; other arrhythmias; Charlson comorbidities index; history of diabetes, hypertension, obesity, prior stroke and peripheral vascular disease; remoteness. Results Of the 9023 eligible separations (52.0% male with mean age 77, SD 13.8 years), 8572 (95%) did not attend CR. Among the 451 patients commencing CR, 352 (78.0%) completed it. CABG (118; 1.3%), PCI (252; 2.8%), diabetes (3031; 33.6%), hypertension (1332; 14.8%) and MI (607; 6.7%) were common diagnoses. Women (OR1.62; 95%CI 1.31-2.02); and older age (OR1.03; 95%CI 1.02-1.04) were associated with a higher risk of not attending CR. Within 12 months of the index hospitalization, there were 4056 (45.0%) CV readmissions/CV deaths and 3486 (38.6%) deaths. After adjustment for demographic, clinical and social factors, CR attendance without completion (p=0.60) or completion (p=0.43) was not associated with CV readmission/CV death. The risk of all-cause death was lower in the groups attending without completing (HR 0.57; 95%CI 0.36-0.91; p=0.02) and completing CR (HR 0.52; 95%CI 0.39-0.71; p=0.02) compared to those not attending CR (Figure 1). Conclusion CR attendance and completion reduces the risk of death within 12 months after a HF hospitalization. Strategies focusing on increasing CR participation should target women and older people who are less likely to attend. A limitation of this study is that we could not control for the utilization of HF-specialist clinics.Survival within 12 months

Abstract 16457: Characterization of LTBP2 Mutation in Causing Mitral Valve Prolapse

Introduction: Mitral Valve Prolapse (MVP) is a cardiac valvular disorder often associated with significant morbidity and mortality with a prevalence of 2.4% in the general population. Familial studies of MVP suggest an autosomal dominant model of inheritance with incomplete penetrance. Hypothesis: The aim of the current study was to identify a genetic etiology for MVP through trait segregation in a progeny with MVP. Methods: We used exome sequencing and segregation analysis to identify mutations linked to MVP in a progeny which includes members. We then generated two strains of mice using Crisper-Cas9 technology, a complete knockout and a knock-in mouse of the top candidate mutation. At 6 months of age echocardiography was done, the mice were sacrificed and the valves were examined pathologically as well as histologically by Movat pentachrome staining. The readers of both the echo and histology were blinded to the genotype. Results: Of 11 genes with rare deleterious mutations only LTBP2 Val1506Met variant (minor allele frequency of 0.0001) segregated with the trait with a LOD score of 1.5[-DR1] . Knockout mice were more likely to demonstrate myxomatous changes by histology (7 of 9 vs 2 of 6 animals, p=0.03) and echocardiography (14 of 22 vs 1 of 8, p=0.01). Knock-in mice demonstrated significantly higher phenotype rate by histology (8 of 8 vs 0 of 7, p<0.0005) and higher nominal phenotype by echo (4 of10 vs 1 of 9, p=0.2). Conclusions: LTBP2 Val1506Met variant segregated with MVP in a large pedigree. Animal models that recapitulate the phenotype suggest that the mutation is indeed pathogenic and leads to myxomatous valvular change.