Deletion Of Element Research Articles

Protective effect of sestrin2 against iron overload and ferroptosis-induced liver injury

Ferroptosis is the non-apoptotic form of cell death caused by small molecules or conditions that inhibit glutathione biosynthesis or resulting in iron-dependent accumulation of lipid peroxidation by lipid reactive oxygen species (ROS). Sestrin2 (Sesn2), a conserved antioxidant protein, is responsive to various stresses including genotoxic, metabolic, and oxidative stresses and acts to restore homeostatic balance. Sesn2 expression was reported to be regulated via stress-responsive transcription factors including p53, Nrf2, and HIF-1α. However, the role of Sesn2 in regulating ferroptosis is not known. In the current study, we investigated whether ferroptosis inducing compounds including erastin, sorafenib, and buthionine sulfoximine affect Sesn2 expression and the role of Sesn2 in cytoprotection against ferroptosis-mediated cell death. Our data demonstrate that ferroptosis inducers significantly increased Sesn2 in hepatocytes in a dose- and time-dependent manner. Treatment with erastin upregulated Sesn2 mRNA levels and luciferase reporter gene activity, and erastin-mediated Sesn2 induction was transcriptionally regulated by NF-E2-related factor 2 (Nrf2). Furthermore, deletion of the antioxidant response element (ARE) in the Sesn2 promoter or Nrf2 knockout or knockdown abolished erastin-induced Sesn2 expression. In cells expressing Sesn2, erastin-induced cell death, ROS formation, and glutathione depletion were almost completely inhibited compared to that in control cells. Treatment with phenylhydrazine in mice, well-reported iron overload liver injury model, increased ALT and AST levels and altered histological features, which were almost completely inhibited by adenoviral Sesn2 infection. Collectively, our results suggest that ferroptosis-mediated Sesn2 induction is dependent on Nrf2 and plays a protective role against iron overload and ferroptosis-induced liver injury.

Lightning ablation suppression of aircraft carbon/epoxy composite laminates by metal mesh

Three-dimensional finite element (FE) models of carbon/epoxy composite laminates with copper mesh and aluminum mesh protection were established subjected to lightning strike, in which different mesh spacing was selected. Effectiveness of numerical method was verified and impulse current waveforms with different current peaks were applied according to aircraft lightning zones. Thermal-electrical material parameters varying with temperature were added into numerical models. Element deletion method was used to deal with lightning ablation elements of composite structures. The results show that ablation area and depth of composite laminates with metal mesh protection are significantly smaller, which proves good protection effectiveness of metal meshes on anti-lightning strike. The denser the mesh spacing, the better the anti-lightning strike will be. Protection of composite laminates with copper mesh has better effects than that of aluminum mesh. Considering the effect of mesh spacing variation on composite structural weight and anti-lightning strike, the ideal mesh spacing was obtained.

Impact analysis of thermally pre-damaged reinforced concrete slabs: Verification of the 3D FE model

To verify recently developed coupled thermo-mechanical and multi-body dynamic finite element (FE) code the influence of thermally induced damage of reinforced concrete (RC) slabs on their impact properties is numerically investigated. The RC slabs are first pre-damaged through fire load and then loaded by impact of hammer. Transient 3D FE thermo-mechanical analysis is performed. Subsequently, impact simulation is conducted that is based on the explicit multi body dynamic analysis and contact algorithm with adaptive element deletion technic. As a constitutive law for concrete rate and temperature dependent microplane model is employed. The co-rotational Cauchy stress tensor and Green-Lagrange strain tensor are used in the framework of total Lagrange FE formulation. The numerical results are discussed and compared with those obtained experimentally. It is shown that the simulation is able to realistically replicate the experimental tests and that the pre-damage of RC slab through fire significantly reduces impact resistance of RC slabs.

A multiscale modeling for failure predictions of fiber reinforced composite laminates

A three-dimensional multiscale damage modeling, based on the parametric High Fidelity Generalized Method of Cells (HFGMC) micromechanics and integrated with a finite-element (FE) code, is proposed to predict the mechanical response, including damage evolution, as well as to generate failure envelopes of composite laminates. A hexagonal repeating unit-cell (RUC) is used to represent explicitly the fiber and matrix phases of a lamina at the microscale level. Failure of a lamina is determined by using both strain-based and stress-based failure theories. This modeling approach is implemented as a user material subroutine (UMAT) within displacement-based Solid FE models, where each solid element is represented by one material point. When the modeled damage is propagating within the macroscale FE model, the material points are eliminated from the FE calculations by using the element deletion approach. The efficiency of the proposed multiscale modeling is demonstrated by a comparison of simulated results with measured data available in the literature.

The third Sandia fracture challenge: predictions of ductile fracture in additively manufactured metal

The Sandia Fracture Challenges provide a forum for the mechanics community to assess its ability to predict ductile fracture through a blind, round-robin format where mechanicians are challenged to predict the deformation and failure of an arbitrary geometry given experimental calibration data. The Third Challenge (SFC3) required participants to predict fracture in an additively manufactured (AM) 316L stainless steel bar containing through holes and internal cavities that could not have been conventionally machined. The volunteer participants were provided extensive data including tension and notched tensions tests of 316L specimens built on the same build-plate as the Challenge geometry, micro-CT scans of the Challenge specimens and geometric measurements of the feature based on the scans, electron backscatter diffraction (EBSD) information on grain texture, and post-test fractography of the calibration specimens. Surprisingly, the global behavior of the SFC3 geometry specimens had modest variability despite being made of AM metal, with all of the SFC3 geometry specimens failing under the same failure mode. This is attributed to the large stress concentrations from the holes overwhelming the stochastic local influence of the AM voids and surface roughness. The teams were asked to predict a number of quantities of interest in the response based on global and local measures that were compared to experimental data, based partly on Digital Image Correlation (DIC) measurements of surface displacements and strains, including predictions of variability in the resulting fracture response, as the basis for assessment of the predictive capabilities of the modeling and simulation strategies. Twenty-one teams submitted predictions obtained from a variety of methods: the finite element method (FEM) or the mesh-free, peridynamic method; solvers with explicit time integration, implicit time integration, or quasi-statics; fracture methods including element deletion, peridynamics with bond damage, XFEM, damage (stiffness degradation), and adaptive remeshing. These predictions utilized many different material models: plasticity models including J2 plasticity or Hill yield with isotropic hardening, mixed Swift-Voce hardening, kinematic hardening, or custom hardening curves; fracture criteria including GTN model, Hosford-Coulomb, triaxiality-dependent strain, critical fracture energy, damage-based model, critical void volume fraction, and Johnson-Cook model; and damage evolution models including damage accumulation and evolution, crack band model, fracture energy, displacement value threshold, incremental stress triaxiality, Cocks-Ashby void growth, and void nucleation, growth, and coalescence. Teams used various combinations of calibration data from tensile specimens, the notched tensile specimens, and literature data. A detailed comparison of results based of these different methods is presented in this paper to suggest a set of best practices for modeling ductile fracture in situations like the SFC3 AM-material problem. All blind predictions identified the nominal crack path and initiation location correctly. The SFC3 participants generally fared better in their global predictions of deformation and failure than the participants in the previous Challenges, suggesting the relative maturity of the models used and adoption of best practices from previous Challenges. This paper provides detailed analyses of the results, including discussion of the utility of the provided data, challenges of the experimental-numerical comparison, defects in the AM material, and human factors.

Prediction of insertion torque and stiffness of a dental implant in bovine trabecular bone using explicit micro-finite element analysis

The assessment of dental implant performance is dominated by the concept of mechanical stability. Primary stability is defined as the capacity of a bone-implant structure to bear loads without occurrence of excessive damage and loosening. In order to achieve the highest primary stability, dental implants are inserted into bone using a press-fit procedure. Pre- and postoperative evaluation of primary stability using implantation torque and resonance frequency analysis are valid approaches but do not allow the systematic comparison of different protocols in similar situations. The aim of this research is to develop and validate an explicit, micro-finite element (μFE) methodology to study the effect of different amounts of initial press-fit on implantation torque and initial stiffness of a dental implant. Ten bovine trabecular bone samples were prepared that cover a wide range of bone volume fraction. A dental implant was inserted using two implantation protocols named soft (small initial drilled hole) and dense (increased initial drilled hole). The implantation torque was measured and the stiffness was calculated using an infinitesimal off-axis loading. Finite element simulations of the implant insertion and subsequent loading were performed on micro-computed tomography (μCT) reconstructions of the samples using an explicit solver. Bone was defined as an elasto-plastic material with von Mises yield criteria and hardening. Element deletion was triggered by a threshold in cumulated plastic strains. A sensitivity analysis was performed on friction, hardening and fracture strain to provide a better insight into the effects of these parameters on the results. The implantation torque required for the soft protocol was higher compared to the dense approach in both experiment and simulation due to the higher amount of bone compaction in the first approach. Interestingly, stiffness did not show a significant dependency on the drilling protocol in both experiment and simulation. In conclusion, the explicit microFE methodology developed in this study was able to capture the outcome of two drilling protocols in terms of torque and stiffness and represents a powerful tool to explore the effect of different parameters on primary stability of dental implants.

The third Sandia Fracture Challenge: from theory to practice in a classroom setting

Three computational methods for modeling fracture are compared in the context of a class’ participation in the Third Sandia Fracture Challenge (SFC3). The SFC3 was issued to assess blind predictions of ductile fracture in a complex specimen geometry produced via additive manufacturing of stainless steel 316L powder. In this work, three finite-element-based methods are investigated: (1) adaptive remeshing, with or without material-state mapping; (2) element deletion; and (3) the extended finite element method. Each student team was tasked with learning about its respective method, calibrating model parameters, and performing blind prediction(s) of fracture/failure in the challenge-geometry specimen. Out of 21 teams who participated in the SFC3, three of the seven student teams from this class project ranked among the top five based on either global force-displacement or local strain predictions. Advantages and disadvantages of the three modeling approaches are identified in terms of mesh dependency, user-friendliness, and accuracy compared to experimental results. Recommendations regarding project management and organization are offered to facilitate future classroom participation in the Sandia Fracture Challenge or similar blind round-robin exercises.

Recovery of Muscovy duck-origin goose parvovirus from an infectious clone containing an E-box motif (CACATG) deletion within the left terminal region

Muscovy duck-origin goose parvovirus (MDGPV) is a causative agent of MDGPV-associated Derzsy's disease. To evalute the role of the cis-acting element E-box (CACATG) deletion on MDGPV eplication, an infectious plasmid clone p-PTΔE287, having one E-box deletion at nucleotide (nt) 287 of the left inverted terminal repeat sequence (L-ITR), was constructed by overlap extension PCR deleting the 287CACATG292 motif from the plasmid pMDGPVPT containing the full-length genome of the virulent MDGPV strain PT. The p-PTΔE287 plasmid was transfected into 9-day-old non-immune Muscovy duck embryos via the yolk sac, resulting in successful rescue of the deletion mutant virus r-PTΔE287. Compared with its parental virus PT, the virulence and the replication ability of r-PTΔE287 were reduced. In addition, we examined the ability of r-PTΔE287 to manipulate cell cycle progression. The results showed that r-PTΔE287 replication results in G0/G1 phase accumulation of infected duck embryo liver mesenchymal stem cells (BMSCs) and that this accumulation is caused by the prevention of cell cycle entry from G0/G1 phase into S phase. Taken together, introducing 287CACATG292 element deletion into MDGPV PT genomic DNA that induced rescued mutant virus (r-PTΔE287) cell cycle arrest function at the G0/G1 phase, which might inhibit MDGPV replication and virus progeny production. This study laid the foundation for further understanding of the relationship between E-box deletion in the L-ITR and MDGPV virulence.

Cutting Simulation Analysis of the Cutter Head of the Shield Machine

In the process of shield machine tunneling, the interaction between cutter head and soil is very complex. In order to meet the requirements of tunneling, the cutter head was designed according to the construction conditions of Tianjin metro and the Archimedes spiral layout method. The granite model and cutter head model were respectively established by the ABAQUS. The granite model was based on the classic Drucker - Pragel model, and the failure criterion including element deletion function was employ to simulate the yield and failure of rock. The force of the cutter head under cutting condition was analyzed. The results show that the maximum equivalent stress of the cutter head is 8.216950 MPa, and the allowable stress of the cutter head material is 230 MPa, which was less than the allowable stress of the cutter head. The results indicated that the cutter head can meet the actual work requirements and has high structural reliability. The research process of cutter head arrangement provides a method for solving practical engineering problems, and the numerical simulation results provide a reference for the design of cutter head.

Synergistic effects of HSE and LTR elements from hsp70 gene promoter of Ulva prolifera (Ulvophyceae, Chlorophyta) upon temperature induction1.

Besides heat stress, the 70kDa heat shock proteins (HSP70s) have been shown to respond to cold stress. However, the involved cis-acting elements remain unknown. The hsp70 gene from the green macroalga Ulva prolifera (Uphsp70) has been cloned, from which one heat shock element HSE and one low-temperature-responsive element LTR were found in the promoter. Using the established transient expression system and quantitative GUS assay, a series of element deletion experiments were performed to determine the functions of HSE and LTR in response to temperature stress. The results showed that under cold stress, both HSE and LTR were indispensable, since deletion leads to complete loss of promoter activity. Under heat stress, although the HSE could respond independently, coexistence with LTR was essential for high induced activity of the Uphsp70 promoter. Therefore, synergistic effects exist between HSE and LTR elements in response to temperature stress in Ulva, and extensive bioinformatics analysis showed that the mechanism is widespread in algae and plants, since LTR coexists widely with HSE in the promoter region of hsp70. Our findings provide important supplements to the knowledge of algal and plant HSP70s response to temperature stress. We speculated that for algal domestication and artificial breeding, HSE and LTR elements might serve as potential molecular targets to temperature acclimation.

Study of angular cutting conditions using multiple scratch tests onto low carbon steel: An experimental-numerical approach

Multiple parallel scratches are often analyzed to understand the material removal mechanisms due to abrasion. However, successive scratches with different orientations may represent better the conditions found in machining processes, such as honing and belt finishing. The objective of this work was to analyze the cutting forces and the phenomena of material removal due to abrasion, arising from angular scratches in low carbon steel. Experimental and numerical techniques were considered. In both, analyses considered the presence of an initial set of parallel scratches, followed by a second set of scratches with different orientations (10, 20 or 30°) with respect to the previous one. The cutting action was performed by a tool representing an abrasive particle, which had a cono-spherical geometry with 235 µm tip radius and 30° apex angle. The cutting settings were: 50 m/min scratch velocity and 100 µm depth of cut. In the experimental part, scratches were conducted using a shaper machine tool equipped with a tungsten carbide (WC-Co) stylus. Tests were conducted on a Kistler platform, which allowed force measurement. Surfaces were later analyzed with an optical profilometer. The numerical simulations considered a ductile damage model with element deletion to provide the material removal during the scratches. Experimental and numerical results showed that the angle affects the cutting forces, especially when one scratch crosses a previously scratched region. The 20° case was the most critical, especially in terms of the cutting forces, due to the accentuated material strain-hardening for this condition. Likewise, this fact was corroborated by numerical results, which indicated a higher energy necessary to plastic deformation, and a reduced material removal at 20°.

Launch Performance Degradation of the Rupture-Type Missile Canister

This paper describes the degradation of launch performance caused by the remnants of a missile canister cover with a sabot interface, on interference with adjacent structures. First, by including the material plastic behavior and element deletion, we predict interference between the structures and the detached part, followed by excessive deformation. Second, we verify that the support ring deformation, which is induced by an interaction with the cover remains, increases for fastener separations with abnormal fastener installations. This increase further triggers interference with the boosters on the bottom of a missile. Lastly, we analyze the variation of material property in a high-speed environment.

3D micro-mechanical modelling of orthogonal cutting of UD-CFRP using smoothed particle hydrodynamics and finite element methods

FE models of orthogonal cutting of FRP composites are usually used implementing element deletion when the failure condition has been reached. This typically results in loss of contact between tool and workpiece during cutting leading to very poor thrust force prediction. In this study, a comprehensive three-dimensional numerical model of orthogonal cutting of UD-CFRP employing the SPH method at the micro-scale level is developed for different fibre orientations (θ=0°, 45°, 90°, 135°). Results are compared with those obtained by a FEM model and against experimental findings. Results show that the SPH method is able to improve prediction of cutting force (∼30% at θ=0°) and thrust force (∼30% at θ=90°, 135°), showing also a chip formation mechanism closer to that experimentally observed. In addition, the developed approach allows simulating the bouncing back, that for θ=0° results equal to the cutting edge radius (∼5 μm), as expected from the literature, and calculating the actual depth of cut.

An explicit micro-FE approach to investigate the post-yield behaviour of trabecular bone under large deformations.

Homogenised finite element (FE) analyses are able to predict osteoporosis-related bone fractures and become useful for clinical applications. The predictions of FE analyses depend on the apparent, heterogeneous, anisotropic, elastic, and yield material properties, which are typically determined by implicit micro-FE (μFE) analyses of trabecular bone. The objective of this study is to explore an explicit μFE approach to determine the apparent post-yield behaviour of trabecular bone, beyond the elastic and yield properties. The material behaviour of bone tissue was described by elasto-plasticity with a von Mises yield criterion closed by a planar cap for positive hydrostatic stresses to distinguish the post-yield behaviour in tension and compression. Two ultimate strains for tension and compression were calibrated to trigger element deletion and reproduce damage of trabecular bone. A convergence analysis was undertaken to assess the role of the mesh. Thirteen load cases using periodicity-compatible mixed uniform boundary conditions were applied to three human trabecular bone samples of increasing volume fractions. The effect of densification in large strains was explored. The convergence study revealed a strong dependence of the apparent ultimate stresses and strains on element size. An apparent quadric strength surface for trabecular bone was successfully fitted in a normalised stress space. The effect of densification was reproduced and correlated well with former experimental results. This study demonstrates the potential of the explicit FE formulation and the element deletion technique to reproduce damage in trabecular bone using μFE analyses. The proper account of the mesh sensitivity remains challenging for practical computing times.

Improvement of windshield laminated glass model for finite element simulation of head-to-windshield impacts

The automotive windshield, with which pedestrians come into frequent contact during car accidents, has been identified as one of the main sources for severe pedestrian head injuries. Finite element simulation of head-to-windshield is widely used for the design and evaluation of car safety performance. Most of the windshield models used in the simulations for pedestrian head injury studies are simplified model. However, accurate modelling of windshield mechanical behaviour is necessary for good prediction of head injury during car-to-pedestrian collision. The purpose of this paper is to improve the model of automobile windshield for simulation of a collision between a pedestrian and a car. The laminated glass windshields of various thickness were tested according to UNECE R43. The deformation and crack pattern were recorded for validation of the finite element model. The finite element models of two layers and three layers laminate glass were developed. Element deletion method and share node techniques were employed for crack propagation pattern. Appropriate mesh size and shaped were obtained. The simulation results were compared with the experimental results of ball drop tests. The simulation results of the laminated glass model with two layers, lmm-triangle mesh shows good agreement with the experimental results. This laminated glass model was then implemented to the windshield of the car. Simulation of headform impact tests according to the EEVC protocol on pedestrian protection were performed. The results in terms of head deceleration, crack pattern and windshield energy absorption were compared with the test results. Good agreement can be seen.

Will Attention by Vaccine Developers to the Host's Nuclear Hormone Levels and Immunocompetence Improve Vaccine Success?

Despite extraordinary advances in fields of immunology and infectious diseases, vaccine development remains a challenge. The development of a respiratory syncytial virus vaccine, for example, has spanned more than 50 years of research with studies of more than 100 vaccine candidates. Dozens of attractive vaccine products have entered clinical trials, but none have completed the path to licensing. Human immunodeficiency virus vaccine development has proven equally difficult, as there is no licensed product after more than 30 years of pre-clinical and clinical research. Here, we examine vaccine development with attention to the host. We discuss how nuclear hormones, including vitamins and sex hormones, can influence responses to vaccines. We show how nuclear hormones interact with regulatory elements of immunoglobulin gene loci and how the deletion of estrogen response elements from gene enhancers will alter patterns of antibody isotype expression. Based on these findings, and findings that nuclear hormone levels are often insufficient or deficient among individuals in both developed and developing countries, we suggest that failed vaccine studies may in some cases reflect weaknesses of the host rather than the product. We encourage analyses of nuclear hormone levels and immunocompetence among study participants in clinical trials to ensure the success of future vaccine programs.

Circumventing mesh bias by r- and h-adaptive techniques for variational eigenfracture

This article introduces and compares mesh r- and h-adaptivity for the eigenfracture model originally proposed in Schmidt et al. (Multiscale Model Simul 7:1237–1266, 2009), Pandolfi and Ortiz (J Numer Methods Eng 92:694–714, 2012), with the goal of suppressing potential mesh bias due to the element deletion. In the r-adaptive approach, we compute the configurational force at each incremental step and move nodes near the crack tip parallel to the normalized configurational forces field such that the crack propagation direction can be captured more accurately within each incremental step. In the h-adapative approach, we introduce mesh refinement via a quad-tree algorithm to introduce more degrees of freedom within the nonlocal $$\epsilon $$-neighborhood such that a more refined crack path can be reproduced with a higher mesh resolution. Our numerical examples indicate that the r-adaptive approach is able to replicate curved cracks and complex geometrical features, whereas the h-adaptive approach is advantageous in simulating sub-scale fracture when the nonlocal regions are smaller than the un-refined coarse mesh.

Crystal plasticity finite element modeling and simulation of diamond cutting of polycrystalline copper

Microstructural-related deformation behavior leads to anisotropic machining characteristics of polycrystalline materials. In the present work, we develop a crystal plasticity finite element model of ultra-precision diamond cutting of polycrystalline copper, aiming to evaluate the influence of grain boundaries on the correlation between microscopic deformation behavior of the material and macroscopic machining results. The crystal plasticity dealing with the anisotropy of polycrystalline copper is implemented in a user subroutine (UMAT), and an efficient element deletion technique based on the Johnson-Cook damage model is adopted to describe material removal and chip formation. The effectiveness of as-established crystal plasticity finite element model is verified by experiments of nanoindentation, nanoscratching and in-situ diamond microcutting. Subsequent crystal plasticity finite element simulation of diamond cutting across a high angle grain boundary demonstrates significant anisotropic machining characteristics in terms of machined surface quality, chip profile and cutting force, due to heterogeneous plastic deformation behavior in the grain level.

Effect of crystallographic texture on the forming limit in microforming of brass

Microforming is an emerging technology to manufacture products in the light of miniaturization in several domains of industry. Plastic anisotropy is one of the material characteristics significantly affecting the micro forming process. The crystal orientation influences tensile strength, yield strength and ductility, depending on different grain sizes and principle sliding planes. The present work elaborates on the influence of the plastic anisotropic in microforming for a plane stress state condition. Yield function and constitutive equations for the anisotropic material with consideration of the crystal lattice constants and parameters of crystallography texture are proposed. The crystal orientation is considered in a subroutine VUMAT algorithm, as an internal variable based on the developed mathematical model which is implemented in Abaqus as an user material subroutine. Micro limiting dome height experimental tests for different strain paths are conducted with brass foils. The results are compared with that predicted with numerical analysis, considering critical damage and element deletions. The numerical and experimental results show a good agreement for the Alpha brass ultra-thin foils, using a set of failure criterion.

Expression of the Human Alpha-Globin Cluster in the Absence of the Major Regulatory Element Mcs-R2

The alpha-globin genes are located in the subtelomeric region of the short arm of chromosome 16. Expression of each allele is controlled by 4 distal cis-acting enhancers (MCS-R1-4) located 48, 40, 33 and 10kb upstream of the duplicated structural alpha genes . Experimental and clinical studies have shown that R1 and R2 are the most important enhancers of alpha-globin production. Here we present an individual with alpha thalassemia who inherited one copy of chromosome 16 from which both alpha genes have been deleted (–SEA). This individual's other copy of chromosome 16 harbours a small deletion of R2. Thus all alpha-globin expression in this individual originates from one copy of the alpha cluster in which R1 drives expression of the two alpha-globin genes in cis. Remarkably, this patient maintains a relatively normal degree of oxygenation despite a severe degree of alpha thalassemia.This female patient was born in Surinam and her mother and father were of Indian and Indonesian origins respectively. She most recently presented, aged 26 yrs, with tiredness and shortness of breath on exertion. She had no previously diagnosed medical conditions, but had received two blood transfusions as a child, both prompted by concurrent infections. Her growth and development were normal. She had suffered one miscarriage at 13 weeks gestation aged 25 yrs. There was nothing of note in the family history and the patient is currently employed as a clerical worker. Cardiovascular examination was normal with no hepatosplenomegaly. Her CBC was consistent with HbH disease, with a Hb of 73g/L, Hct 25%, MCV 45fl, MCH 13.2pg with a blood film showing marked microcytosis anisopoikilocytosis, target cells and 30.7% HbH inclusions on Brilliant Cressyl Blue staining. HPLC showed evidence of a fast-moving band, HbA 88.4% and HbA2 1.3%, HbE 5.1%. MLPA analysis showed that the father and proband both carried heterozygous deletions of R2, and the mother and proband both carried the –SEA deletion on one allele. Due to the severity of the anaemia and the striking red cell indices it was highly likely that she had intact regulatory elements in cis with the –SEA deletion on one allele, and on the other, a regulatory network missing R2 lying upstream of the two intact alpha-globin genesTo investigate this further, CD34+ cells were extracted from the patient's peripheral blood and differentiated using a liquid culture system (Trakarnsanga et al. Nature Comms. 2017). The alpha/non-alpha-globin synthetic ratio of mRNA as measured by qPCR at peak globin-production was markedly reduced compared to WT cells and those of a patient carrying the –SEA deletion on one allele alone: WT 1.26, SEA 0.65, Patient 0.11.The upstream enhancers are associated with regions of open chromatin that can be detected by chromatin accessibility assays. To see whether the deletion of R2 had caused new regulatory elements to appear or whether accessibility of the existing elements was altered, ATAC-seq was performed on Day 13 of differentiation. This showed a reduction in the peak at R2 in keeping with its deletion on one allele, but showed no change in the peak height of R1 compared to that in the individual with the –SEA deletion alone or WT.To assess chromatin interactions across the domain Capture-C, a sensitive assay to detect interactions between selected regions of chromatin, was performed (Davies et al. Nature Methods 2016). Compared to WT, when capturing from the alpha-globin promoters interactions with R1, R3 and R4 were observed with no interactions with R2 detected, in keeping with the hypothesised distribution of deletions. No interactions in trans between the intact R2 and alpha-globin genes were detected.Previous cases of deletions of the upstream alpha-globin regulatory element have either involved deletions of the regulatory elements on one allele only, or involved both alleles but with a full complement of alpha genes. Our findings show that whilst a severe HbH phenotype was observed, it is possible to maintain transfusion independence with only R1, R3, R4 and two alpha-globin genes. Considering the ATAC-seq and Capture-C findings, as well as comparison with the homologous locus in mouse it is likely that the bulk of regulation in this patient occurs via R1. The observed phenotype is consistent with redundancy within the regulatory elements of the alpha gene locus, which may enable continued expression of key cell-specific genes in the event of adverse genotypic events. Disclosuresvan Beers:RR Mechatronics: Research Funding; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bayer: Research Funding; Pfizer: Research Funding.