Horizontal gene transfer from diverse bacteria to an insect genome enables a tripartite nested mealybug symbiosis.

The smallest reported bacterial genome belongs to Tremblaya princeps, a symbiont of Planococcus citri mealybugs (PCIT). Tremblaya PCIT not only has a 139 kb genome, but possesses its own bacterial endosymbiont, Moranella endobia. Genome and transcriptome sequencing, including genome sequencing from a Tremblaya lineage lacking intracellular bacteria, reveals that the extreme genomic degeneracy of Tremblaya PCIT likely resulted from acquiring Moranella as an endosymbiont. In addition, at least 22 expressed horizontally transferred genes from multiple diverse bacteria to the mealybug genome likely complement missing symbiont genes. However, none of these horizontally transferred genes are from Tremblaya, showing that genome reduction in this symbiont has not been enabled by gene transfer to the host nucleus. Our results thus indicate that the functioning of this three-way symbiosis is dependent on genes from at least six lineages of organisms and reveal a path to intimate endosymbiosis distinct from that followed by organelles.

Gene-rich germline-restricted chromosomes in black-winged fungus gnats evolved through hybridization.

Germline-restricted DNA has evolved in diverse animal taxa and is found in several vertebrate clades, nematodes, and flies. In these lineages, either portions of chromosomes or entire chromosomes are eliminated from somatic cells early in development, restricting portions of the genome to the germline. Little is known about why germline-restricted DNA has evolved, especially in flies, in which 3 diverse families, Chironomidae, Cecidomyiidae, and Sciaridae, carry germline-restricted chromosomes (GRCs). We conducted a genomic analysis of GRCs in the fungus gnat Bradysia (Sciara) coprophila (Diptera: Sciaridae), which has 2 large germline-restricted "L" chromosomes. We sequenced and assembled the genome of B. coprophila and used differences in sequence coverage and k-mer frequency between somatic and germline tissues to identify GRC sequence and compare it to the other chromosomes in the genome. We found that the GRCs in B. coprophila are large, gene rich, and have many genes with divergent homologs on other chromosomes in the genome. We also found that 2 divergent GRCs exist in the population we sequenced. GRC genes are more similar in sequence to genes from another Dipteran family (Cecidomyiidae) than to homologous genes from Sciaridae. This unexpected finding suggests that these chromosomes likely arose in Sciaridae through hybridization with a related lineage. These results provide a foundation from which to answer many questions about the evolution of GRCs in Sciaridae, such as how this hybridization event resulted in GRCs and what features on these chromosomes cause them to be restricted to the germline.

Gene-rich X chromosomes implicate intragenomic conflict in the evolution of bizarre genetic systems.

Haplodiploidy and paternal genome elimination (HD/PGE) are common in invertebrates, having evolved at least two dozen times, all from male heterogamety (i.e., systems with X chromosomes). However, why X chromosomes are important for the evolution of HD/PGE remains debated. The Haploid Viability Hypothesis posits that X-linked genes promote the evolution of male haploidy by facilitating purging recessive deleterious mutations. The Intragenomic Conflict Hypothesis holds that conflict between genes drives genetic system turnover; under this model, X-linked genes could promote the evolution of male haploidy due to conflicts with autosomes over sex ratios and genetic transmission. We studied lineages where we can distinguish these hypotheses: species with germline PGE that retain an XX/X0 sex determination system (gPGE+X). Because evolving PGE in these cases involves changes in transmission without increases in male hemizygosity, a high degree of X linkage in these systems is predicted by the Intragenomic Conflict Hypothesis but not the Haploid Viability Hypothesis. To quantify the degree of X linkage, we sequenced and compared 7 gPGE+X species' genomes with 11 related species with typical XX/XY or XX/X0 genetic systems, representing three transitions to gPGE. We find highly increased X linkage in both modern and ancestral genomes of gPGE+X species compared to non-gPGE relatives and recover a significant positive correlation between percent X linkage and the evolution of gPGE. These empirical results substantiate longstanding proposals for a role for intragenomic conflict in the evolution of genetic systems such as HD/PGE.

Recent Evolution of a Maternally Acting Sex-Determining Supergene in a Fly with Single-Sex Broods.

Sex determination is a key developmental process, yet it is remarkably variable across the tree of life. The dipteran family Sciaridae exhibits one of the most unusual sex determination systems in which mothers control offspring sex through selective elimination of paternal X chromosomes. Whereas in some members of the family females produce mixed-sex broods, others such as the dark-winged fungus gnat Bradysia coprophila are monogenic, with females producing single-sex broods. Female-producing females were previously found to be heterozygous for a large X-linked paracentric inversion (X'), which is maternally inherited and absent from male-producing females. Here, we assembled and characterized the X' sequence. As close sequence homology between the X and X' made identification of the inversion challenging, we developed a k-mer-based approach to bin genomic reads before assembly. We confirmed that the inversion spans most of the X' chromosome (∼55 Mb) and encodes ∼3,500 genes. Analysis of the divergence between the inversion and the homologous region of the X revealed that it originated very recently (<0.5 Ma). Surprisingly, we found that the X' is more complex than previously thought and is likely to have undergone multiple rearrangements that have produced regions of varying ages, resembling a supergene composed of evolutionary strata. We found functional degradation of ∼7.3% of genes within the region of recombination suppression, but no evidence of accumulation of repetitive elements. Our findings provide an indication that sex-linked inversions are driving turnover of the strange sex determination system in this family of flies.

Predictors and prognosis of pulmonary hypertension complicating interstitial lung disease in systemic sclerosis.

OBJECTIVE: To identify those with concurrent pulmonary hypertension (PH) and interstitial lung disease (ILD) in systemic sclerosis (SSc) and determine their disease severity, therapeutic approach, and survival. METHODS: Consecutive SSc patients enrolled in the Australian Scleroderma Cohort Study (ASCS) who were diagnosed on right heart catherisation with pulmonary hypertension were included. Logistic regression was used to determine the associations of ILD with PH hemodynamic parameters and therapeutic approach. Kaplan-Meier survival curves were used to estimate survival. RESULTS: Of 1,883 SSc patients, 164 (8.7%) developed incident PH over a median follow up of 4.3 (1.7-7.9) years. Of these, 43.9% had concurrent ILD at PH diagnosis (PH-ILD) and 56.1% had Group 1 PAH. Extensive ILD was present at PH diagnosis in 40.3%. Despite these distinct PH cohorts, a similar frequency of each PH cohort was treated with vasodilatory therapy at PH diagnosis, regardless of the presence or severity of ILD. The majority (87.5%) of those with extensive ILD and PH received upfront vasodilatory therapy at PH diagnosis with no difference in its tolerability or therapy cessation compared with Group 1 PAH. Although vasodilator therapy was not associated with a survival advantage in those with extensive ILD, its use was associated with an improvement in symptoms, physical function, and quality of life (QoL). CONCLUSION: Despite vasodilator therapy, survival in SSc-PH is poor, with the presence of concurrent ILD associated with worse survival. Although vasodilator therapy commenced at PH diagnosis does not portray an improved survival in PH with extensive ILD, it appears well tolerated and may improve symptoms, physical function, and QoL.

Frequency and implications of malnutrition in systemic sclerosis.

OBJECTIVES: To quantify the frequency and impact of malnutrition in systemic sclerosis (SSc), as diagnosed by the Global Leadership Initiative on Malnutrition (GLIM) criteria, based on weight loss, body mass index (BMI) and muscle atrophy. METHODS: Australian Scleroderma Cohort Study participants meeting ACR/EULAR criteria for SSc with ≥1 concurrent weight and height measurement were included. Chi-squared tests, two-sample t-tests or Wilcoxon rank-sum tests were used for between-group comparison as appropriate. Multivariable logistic regression models were used to establish the determinants of malnutrition diagnosis. Kaplan-Meier and Cox proportional hazard models were used for survival analyses, based on malnutrition diagnosis, and individual GLIM criteria (% weight loss, BMI thresholds and presence of muscle atrophy). RESULTS: In this study of 1903 participants, 43% were diagnosed with malnutrition according to GLIM criteria, of whom 33% had severe malnutrition. Participants diagnosed with malnutrition were older, and more likely to have dcSSc, higher SSc severity scores and RNA polymerase-3 positivity. Gastrointestinal (GI) involvement, multimorbidity, cardiopulmonary disease, raised inflammatory markers, hypoalbuminaemia and anaemia were more common in malnourished participants (p< 0.01). Multimorbidity (OR1.6, 95%CI1.2-2.0, p< 0.01), pulmonary arterial hypertension (OR2.1, 95%CI1.4-2.0, p< 0.01) and upper GI symptoms (OR1.6, 95%CI1.3-2.0, p< 0.01) were all associated with malnutrition.Health-related quality-of-life (HRQoL) and physical function were poorer in malnourished participants. Survival was worse in those with malnutrition after adjusting for age, sex and dcSSc (HR 1.4, 95%CI1.1-1.7, p< 0.01). CONCLUSIONS: Malnutrition is common in SSc and confers poorer survival, HRQoL and physical function.

Examining the Case for Palliative Care in Patients with Systemic Sclerosis.

Systemic sclerosis is a complex, multi-organ disease which causes substantial and progressive symptoms and impairs quality of life. International guidelines recommend early, integrated palliative care for patients with advanced cardiopulmonary disease such as heart failure, and interstitial lung disease, as this care can improve patient, caregiver and health care outcomes. In this article, we examine the potential need and role for palliative care in systemic sclerosis. We propose early, integrated palliative care could improve symptom control and quality of life, and recommend a research agenda for palliative care in systemic sclerosis, to address the lack of evidence in this area.

Contribution of Left Ventricular Diastolic Dysfunction to Survival and Breathlessness in Systemic Sclerosis-Associated Interstitial Lung Disease.

OBJECTIVE: To explore the effect of left ventricular (LV) diastolic dysfunction (LVDD) in systemic sclerosis (SSc)-associated interstitial lung disease (ILD), and to investigate SSc-specific associations and clinical correlates of LVDD. METHODS: There were 102 Australian Scleroderma Cohort Study participants with definite SSc and radiographic ILD included. Diastolic function was classified as normal, indeterminate, or abnormal according to 2016 American Society of Echocardiography/European Association of Cardiovascular Imaging guidelines for assessment of LV diastolic function. Associations between clinical features and patient- and physician-reported dyspnea were evaluated using logistic regression. Survival analyses were performed using Kaplan-Meier survival estimates and Cox regression modeling. RESULTS: LVDD was identified in 26% of participants, whereas 19% had indeterminate and 55% had normal diastolic function. Those with ILD and LVDD had increased mortality (hazard ratio 2.4, 95% CI 1.0-5.7; P = 0.05). After adjusting for age and sex, those with ILD and LVDD were more likely to have severe dyspnea on the Borg Dyspnoea Scale (odds ratio [OR] 2.6, 95% CI 1.0-6.6; P = 0.05) and numerically more likely to record World Health Organization Function Class II or higher dyspnea (OR 4.2, 95% CI 0.9-20.0; P = 0.08). Older age (95% CI 1.0-6.4; P = 0.05), hypertension (OR 5.0, 95% CI 1.8-13.8; P < 0.01), and ischemic heart disease (OR 4.8, 95% CI 1.5-15.7; P < 0.01) were all associated with LVDD, as was proximal muscle atrophy (OR 5.0, 95% CI 1.9-13.6; P < 0.01) and multimorbidity (Charlson Comorbidity Index scores ≥ 4, OR 3.0, 95% CI 1.1-8.7; P = 0.04). CONCLUSION: LVDD in SSc-ILD is more strongly associated with traditional LVDD risk factors than SSc-specific factors. LVDD is associated with worse dyspnea and survival in those with SSc-ILD.

Composite measures to assess disease damage, disease severity and treatment response in systemic sclerosis clinical trials.

PURPOSE OF REVIEW: The aim of this study was to summarize the composite outcome measures available to assess disease damage, severity and treatment response in systemic sclerosis (SSc). RECENT FINDINGS: There have been many recent efforts to rigorously develop and validate composite outcome measures to assess the totality of the impact of SSc on patients. All initiatives have used both consensus and data-driven methods. Recently developed are a SSc-specific damage index, a patient-reported disease impact questionnaire (ScleroID) and a treatment response index (ACR-CRISS). SUMMARY: Multiorgan, composite measures are being increasingly applied to assess treatment efficacy in clinical trials. Although a fully validated, disease-specific composite measure is not yet available, there has been significant recent progress towards developing measures of treatment response, damage and overall impact of SSc for application in randomized controlled trials.

Muscle biopsy practices in the evaluation of neuromuscular disease: A systematic literature review.

AIMS: Muscle biopsy techniques range from needle muscle biopsy (NMB) and conchotome biopsy to open surgical biopsy. It is unknown whether specific biopsy techniques offer superior diagnostic yield or differ in procedural complication rates. Therefore, we aimed to compare the diagnostic utility of NMB, conchotome and open muscle biopsies in the assessment of neuromuscular disorders. METHODS: A systematic literature review of the EMBASE and Medline (Ovid) databases was performed to identify original, full-length research articles that described the muscle biopsy technique used to diagnose neuromuscular disease in both adult and paediatric patient populations. Studies of any design, excluding case reports, were eligible for inclusion. Data pertaining to biopsy technique, biopsy yield and procedural complications were extracted. RESULTS: Sixty-four studies reporting the yield of a specific muscle biopsy technique and, or procedural complications were identified. Open surgical biopsies provided a larger tissue sample than any type of percutaneous muscle biopsy. Where anaesthetic details were reported, general anaesthesia was required in 60% of studies that reported open surgical biopsies. Percutaneous biopsies were most commonly performed under local anaesthesia and despite the smaller tissue yield, moderate- to large-gauge needle and conchotome muscle biopsies had an equivalent diagnostic utility to that of open surgical muscle biopsy. All types of muscle biopsy procedures were well tolerated with few adverse events and no scarring complications were reported with percutaneous sampling. CONCLUSIONS: When a histological diagnosis of myopathy is required, moderate- to large-gauge NMB and the conchotome technique appear to have an equivalent diagnostic yield to that of an open surgical biopsy.

Progressive pulmonary fibrosis and its impact on survival in systemic sclerosis related interstitial lung disease.

OBJECTIVE: To describe the frequency of progressive pulmonary fibrosis (PPF) in an incident cohort of systemic sclerosis (SSc) related interstitial lung disease (ILD) and its impact on survival. METHODS: Incident ILD was defined as the new development of characteristic fibrotic changes on chest HRCT scan. PPF was defined as per the 2022 American Thoracic Society. Determinants of PPF were identified using generalised estimating equations. Impact on survival was analysed using accelerated failure time regression modelling. RESULTS: Of our incident SSc-ILD cases, 38.8% (n = 180) experienced PPF within a 12-month period after ILD diagnosis. Determinants of PPF included older age (OR 1.02, 95%CI 1.00-1.03, p= 0.011), dcSSc (OR 1.54, 95% CI 1.06-2.25, p= 0.024) and SSc specific antibodies (anticentomere antibody OR 0.51, 95%CI 0.29-0.91, p= 0.021 and anti-Scl-70 antibody OR 1.46, 95%CI 1.01-2.09, p= 0.043). Raised CRP was numerically associated with PPF but did not reach statistical significance (OR 1.29, 95%CI 0.99-1.68, p= 0.064) nor did GORD or dysphagia (OR 1.18, 95%CI 0.57-2.42, p= 0.658 and OR 1.17, 95%CI 0.57-2.40, p= 0.664 respectively). The presence of PPF significantly impacted survival in SSc-ILD (hazard ratio 2.66, 95%CI 1.59-4.41, p< 0.001). CONCLUSIONS: PPF occurred in a third of our incident SSc-ILD cohort; however, its occurrence was significantly associated with mortality indicating an at-risk group who may be suitable for earlier introduction of immunosuppressive and/or antifibrotic therapy.

Systemic pharmacological treatment of digital ulcers in systemic sclerosis: a systematic literature review.

OBJECTIVE: To evaluate the evidence concerning systemic pharmacological treatments for SSc digital ulcers (DUs) to inform the development of evidence-based treatment guidelines. METHODS: A systematic literature review of seven databases was performed to identify all original research studies of adult patients with SSc DUs. Randomized controlled trials (RCTs) and prospective longitudinal observational studies (OBSs) were eligible for inclusion. Data were extracted, applying the patient, intervention, comparison, outcome framework, and risk of bias (RoB) was assessed. Due to study heterogeneity, narrative summaries were used to present data. RESULTS: Forty-seven studies that evaluated the treatment efficacy or safety of pharmacological therapies were identified among 4250 references. Data from 18 RCTs of 1927 patients and 29 OBSs of 661 patients, at various RoB (total 2588 patients) showed that i.v. iloprost, phosphodiesterase-5 inhibitors and atorvastatin are effective for the treatment of active DUs. Bosentan reduced the rate of future DUs in two RCTs (moderate RoB) and eight OBSs at low to high RoB. Two small studies (moderate RoB) indicate that Janus kinase inhibitors may be effective for the treatment of active DUs, otherwise there are no data to support the use of immunosuppression or anti-platelet agents in the management of DUs. CONCLUSION: There are several systemic treatments, across four medication classes, that are effective therapies for the management of SSc DUs. However, a lack of robust data means it is not possible to define the optimal treatment regimen for SSc DUs. The relatively low quality of evidence available has highlighted further areas of research need.

Why put all your eggs in one basket? Evolutionary perspectives on the origins of monogenic reproduction.

Sexual reproduction is ubiquitous in eukaryotes, but the mechanisms by which sex is determined are diverse and undergo rapid turnovers in short evolutionary timescales. Usually, an embryo's sex is fated at the moment of fertilisation, but in rare instances it is the maternal genotype that determines the offspring's sex. These systems are often characterised by mothers producing single-sex broods, a phenomenon known as monogeny. Monogenic reproduction is well documented in Hymenoptera (ants, bees and wasps), where it is associated with a eusocial lifestyle. However, it is also known to occur in three families in Diptera (true flies): Sciaridae, Cecidomyiidae and Calliphoridae. Here we review current knowledge of monogenic reproduction in these dipteran clades. We discuss how this strange reproductive strategy might evolve, and we consider the potential contributions of inbreeding, sex ratio distorters, and polygenic control of the sex ratio. Finally, we provide suggestions on future work to elucidate the origins of this unusual reproductive strategy. We propose that studying these systems will contribute to our understanding of the evolution and turnover of sex determination systems.

Multidisciplinary team discussion: the emerging gold standard for management of cardiopulmonary complications of connective tissue disease.

Cardiopulmonary complications of connective tissue diseases (CTDs), particularly pulmonary arterial hypertension (PAH) and interstitial lung disease (ILD), are major determinants of morbidity and mortality. Multidisciplinary meetings may improve diagnostic accuracy and optimise treatment. We review the literature regarding multidisciplinary meetings in CTD-ILD and PAH and describe our tertiary centre experience of the role of the multidisciplinary meeting in managing CTD-PAH.

CATCH-UP vaccines: protocol for a randomized controlled trial using the multiphase optimization strategy (MOST) framework to evaluate education interventions to increase COVID-19 vaccine uptake in Oklahoma.

BACKGROUND: Oklahoma's cumulative COVID-19 incidence is higher in rural than urban counties and higher than the overall US incidence. Furthermore, fewer Oklahomans have received at least one COVID-19 vaccine compared to the US average. Our goal is to conduct a randomized controlled trial using the multiphase optimization strategy (MOST) to test multiple educational interventions to improve uptake of COVID-19 vaccination among underserved populations in Oklahoma. METHODS: Our study uses the preparation and optimization phases of the MOST framework. We conduct focus groups among community partners and community members previously involved in hosting COVID-19 testing events to inform intervention design (preparation). In a randomized clinical trial, we test three interventions to improve vaccination uptake: (1) process improvement (text messages); (2) barrier elicitation and reduction (electronic survey with tailored questions/prompts); and (2) teachable moment messaging (motivational interviewing) in a three-factor fully crossed factorial design (optimization). DISCUSSION: Because of Oklahoma's higher COVID-19 impact and lower vaccine uptake, identifying community-driven interventions is critical to address vaccine hesitancy. The MOST framework provides an innovative and timely opportunity to efficiently evaluate multiple educational interventions in a single study. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05236270, First Posted: February 11, 2022, Last Update Posted: August 31, 2022.

------Widespread conservation and lineage-specific diversification of genome-wide DNA methylation patterns across arthropods.

Cytosine methylation is an ancient epigenetic modification yet its function and extent within genomes is highly variable across eukaryotes. In mammals, methylation controls transposable elements and regulates the promoters of genes. In insects, DNA methylation is generally restricted to a small subset of transcribed genes, with both intergenic regions and transposable elements (TEs) depleted of methylation. The evolutionary origin and the function of these methylation patterns are poorly understood. Here we characterise the evolution of DNA methylation across the arthropod phylum. While the common ancestor of the arthropods had low levels of TE methylation and did not methylate promoters, both of these functions have evolved independently in centipedes and mealybugs. In contrast, methylation of the exons of a subset of transcribed genes is ancestral and widely conserved across the phylum, but has been lost in specific lineages. A similar set of genes is methylated in all species that retained exon-enriched methylation. We show that these genes have characteristic patterns of expression correlating to broad transcription initiation sites and well-positioned nucleosomes, providing new insights into potential mechanisms driving methylation patterns over hundreds of millions of years.

Males That Silence Their Father's Genes: Genomic Imprinting of a Complete Haploid Genome.

Genetic conflict is considered a key driver in the evolution of reproductive systems with non-Mendelian inheritance, where parents do not contribute equally to the genetic makeup of their offspring. One of the most extraordinary examples of non-Mendelian inheritance is paternal genome elimination (PGE), a form of haplodiploidy which has evolved repeatedly across arthropods. Under PGE, males are diploid but only transmit maternally inherited chromosomes, while the paternally inherited homologues are excluded from sperm. This asymmetric inheritance is thought to have evolved through an evolutionary arms race between the paternal and maternal genomes over transmission to future generations. In several PGE clades, such as the mealybugs (Hemiptera: Pseudococcidae), paternal chromosomes are not only eliminated from sperm, but also heterochromatinized early in development and thought to remain inactive, which could result from genetic conflict between parental genomes. Here, we present a parent-of-origin allele-specific transcriptome analysis in male mealybugs showing that expression is globally biased toward the maternal genome. However, up to 70% of somatically expressed genes are to some degree paternally expressed, while paternal genome expression is much more restricted in the male reproductive tract, with only 20% of genes showing paternal contribution. We also show that parent-of-origin-specific gene expression patterns are remarkably similar across genotypes, and that genes with completely biparental expression show elevated rates of molecular evolution. Our results provide the clearest example yet of genome-wide genomic imprinting in insects and enhance our understanding of PGE, which will aid future empirical tests of evolutionary theory regarding the origin of this unusual reproductive strategy.

Myocardial fibrosis and arrhythmic burden in systemic sclerosis.

OBJECTIVES: Cardiac complications of SSc are a leading cause of SSc-associated death. Cardiac imaging for identifying substrate abnormality may be useful in predicting risk of cardiac arrhythmias or future cardiac failure. The aim of this study was to quantify the burden of asymptomatic fibro-inflammatory myocardial disease using cardiac magnetic resonance imaging (CMR) and assess the relationship between asymptomatic myocardial fibrosis and cardiac arrhythmias in SSc. METHODS: Thirty-two patients with SSc with no documented history of pulmonary vascular or heart disease underwent CMR with gadolinium and 24-h ambulatory ECG. Focal myocardial fibrosis was assessed using post-gadolinium imaging and diffuse fibro-inflammatory myocardial disease quantified using T1- and T2-mapping. CMR results were compared with an age- and sex-matched control group. RESULTS: Post-gadolinium focal fibrosis was prevalent in SSc but not controls (30% vs 0%, p < 0.01).. T1-mapping values (as a marker of diffuse fibrosis) were greater in SSc than controls [saturated recovery single-shot acquisition (SASHA): 1584 ms vs 1515 ms, P < 0.001; shortened Modified look locker sequence (ShMOLLI): 1218 ms vs 1138 ms, p < 0.001]. More than one-fifth (22.6%) of the participants had ventricular arrhythmias on ambulatory ECG, but no associations between focal or diffuse myocardial fibrosis and arrhythmias were evident. CONCLUSION: In SSc patients without evidence of overt cardiac disease, a high burden of myocardial fibrosis and arrhythmias was identified. However, there was no clear association between focal or diffuse myocardial fibrosis and arrhythmias, suggesting CMR may have limited use as a screening tool to identify SSc patients at risk of future significant arrhythmias.

The clinical implications of left ventricular diastolic dysfunction in systemic sclerosis.

OBJECTIVES: We sought to quantify the burden of left ventricular diastolic dysfunction (LVDD) and heart failure with preserved ejection fraction (HFpEF) in systemic sclerosis (SSc) and assess the progression of LVDD over time and its prognostic importance. METHODS: Two-hundred and twenty-five participants enrolled in the Australian Scleroderma Cohort Study were included and LVDD was assessed according to 2016 ASE/EACVI Guidelines. Logistic regression analyses and generalised estimating equations were performed to evaluate the relationship between LVDD and SSc disease characteristics and symptoms and signs of heart failure, respectively. The relationship between LVDD and mortality was assessed using Kaplan-Meier survival estimates. RESULTS: Thirty-four (15%) participants were diagnosed with LVDD. A further 89 (40%) participants had indeterminate diastolic function. Older age (p<0.01), hypertension (p=0.02), impaired systolic function (p=0.03) and interstitial lung disease (p=0.01) were all associated with the presence of LVDD. There was no association between the presence of LVDD and clinical signs of heart failure, however, LVDD was associated with more breathlessness and worse functional class (p=0.03). LVDD was observed to progress over time, with significant worsening of parameters of left ventricular filling pressure. There was no significant relationship between LVDD and mortality (p=0.23). CONCLUSIONS: Abnormal diastolic function is a common finding in SSc, progresses over time and is associated with more severe dyspnoea. Whilst patients with LVDD are more breathless, LVDD is not clearly associated with clinical findings of heart failure demonstrating that LVDD may be of importance in explaining symptoms even in the absence of HFpEF in SSc.