Severe Congenital Disease Research Articles

Calcium is reduced in presynaptic mitochondria of motor nerve terminals during neurotransmission in SMA mice.

Spinal muscular atrophy (SMA) is an autosomal recessive degenerative motor neuron disease characterized by symmetrical muscle weakness and atrophy of limb and trunk muscles being the most severe genetic disease in children. In SMA mouse models, motor nerve terminals display neurotransmitter release reduction, endocytosis decrease and mitochondria alterations. The relationship between these changes is, however, not well understood. In the present study, we investigated whether the endocytosis impairment could be related to the functional alteration of the presynaptic mitochondria during action potential (AP) firing. To this aim, we generated a Synaptophysin-pHluorin (SypHy) transgenic mouse, crossed it with Taiwanese SMA mice, and recorded exo- and endocytosis and mitochondria Ca2+ signaling in real-time at ex vivo motor nerve terminals of Taiwanese-SypHy mice. The experiments were performed at the beginning of the motor symptoms to get an integrated view of the nerve terminal’s functional state before degeneration. Our electrophysiological and live imaging results demonstrated that the mitochondria’s capacity to increase matrix-free Ca2+ in SMA mice was significantly limited during nerve AP firing, except when the rate of Ca2+ entry to the cytosol was considerably reduced. These results indicate that both the mitochondrial Ca2+ signaling alterations and the secretion machinery defects are significant players in the dysfunction of the presynaptic terminal in SMA.

A Combined Model of Human iPSC-Derived Liver Organoids and Hepatocytes Reveals Ferroptosis in DGUOK Mutant mtDNA Depletion Syndrome.

Mitochondrial DNA depletion syndrome (MDS) is a group of severe inherited disorders caused by mutations in genes, such as deoxyribonucleoside kinase (DGUOK). A great majority of DGUOK mutant MDS patients develop iron overload progressing to severe liver failure. However, the pathological mechanisms connecting iron overload and hepatic damage remains uncovered. Here, two patients’ skin fibroblasts are reprogrammed to induced pluripotent stem cells (iPSCs) and then corrected by CRISPR/Cas9. Patient‐specific iPSCs and corrected iPSCs‐derived high purity hepatocyte organoids (iHep‐Orgs) and hepatocyte‐like cells (iHep) are generated as cellular models for studying hepatic pathology. DGUOK mutant iHep and iHep‐Orgs, but not control and corrected one, are more sensitive to iron overload‐induced ferroptosis, which can be rescued by N‐Acetylcysteine (NAC). Mechanically, this ferroptosis is a process mediated by nuclear receptor co‐activator 4 (NCOA4)‐dependent degradation of ferritin in lysosome and cellular labile iron release. This study reveals the underlying pathological mechanisms and the viable therapeutic strategies of this syndrome, and is the first pure iHep‐Orgs model in hereditary liver diseases.

Generation and characterization of a novel rat model of primary hyperoxaluria type 1 with a nonsense mutation in alanine-glyoxylate aminotransferase gene.

Primary hyperoxaluria type 1 (PH1) is a severe inherited disorder caused by a genetic defect in alanine-glyoxylate aminotransferase (AGXT), which results in recurrent urolithiasis and renal failure. Animal models that precisely reflect human PH1 phenotypes are lacking. We aimed to develop a novel PH1 rat model and study the mechanisms involved in PH1 deterioration. One cell stage Sprague-Dawley embryos were injected with the CRISPR/Cas9 system to introduce a Q84X mutation in Agxt. Liver tissues were harvested to determine Agxt expression. Urine oxalate, crystals, and electrolyte levels in AgxtQ84X and wild-type (WT) littermates were evaluated. Kidney tissues were used for Pizzolato staining and kidney injury evaluation. Data showed that Agxt mRNA and protein were absent in AgxtQ84X rats. At 4 and 24 wk, AgxtQ84X rats displayed 2.1- and 2.9-fold higher urinary oxalate levels, respectively, compared with WT littermates. As a result, calcium oxalate (CaOx) crystals in urine were revealed in all AgxtQ84X rats but in none of the WT rats. We also observed bladder stones in 36.4% of AgxtQ84X rats, of which 44.4% had renal CaOx deposition. Moreover, the elevated serum urea and creatinine levels indicated the impaired renal function in AgxtQ84X rats. Further investigation revealed significantly increased expression of inflammation-, necroptosis-, and fibrosis-related genes in the kidneys of AgxtQ84X rats with spontaneous renal CaOx deposition, indicating that these pathways are involved in PH1 deterioration. Collectively, these results suggest that this rat model has broad applicability in mechanistic studies and innovative therapeutics development for PH1 and other kidney stone diseases.NEW & NOTEWORTHY Primary hyperoxaluria type 1 is a severe inherited disorder that results in recurrent urolithiasis and renal failure. We generated an alanine-glyoxylate aminotransferase (Agxt)Q84X nonsense mutant rat model that displayed an early onset of hyperoxaluria, spontaneous renal CaOx precipitation, bladder stone, and kidney injuries. Our results suggest an interaction of renal CaOx crystals with the activation of inflammation-, fibrosis-, and necroptosis-related pathways. In all, the AgxtQ84X rat strain has broad applicability in mechanistic studies and the development of innovative therapeutics.

Predictive Prenatal Diagnosis for Infantile-onset Inflammatory Bowel Disease Because of Interleukin-10 Signalling Defects.

Advances in genetic technologies provide opportunities for patient care and ethical challenges. Clinical care of patients with rare Mendelian disorders is often at the forefront of those developments. Whereas in classical polygenic inflammatory bowel disease (IBD), the predictive value of genetic variants is very low, predictive prenatal genetic diagnosis can inform families at high risk of severe genetic disorders. Patients with IL-10 signalling defects because of pathogenic variants in IL10RA, Il10RB, and IL10 develop severe infantile onset inflammatory bowel disease that is completely penetrant and has a high morbidity and substantial mortality despite treatment. We performed a survey among tertiary specialist paediatric centers of 10 countries on the utilization of predictive prenatal genetic diagnosis in IL-10 signalling defects. We retrospectively report prenatal genetics in a series of 8 families. International variation in legislation, guidelines, expert opinion, as well as cultural and religious background of families and clinicians results in variable utilization of preimplantation and prenatal genetic testing for IL-10 signalling defects. Eleven referrals for prenatal diagnosis for IL-10 signalling defects were identified across 4 countries. We report on 8 families who underwent prenatal preimplantation monogenic testing after in vitro fertilization (n = 2) and/or by amniocentesis/chorion villus sampling (n = 6). A genetic diagnosis was established in 1 foetus and excluded in 7 foetuses (all IL10RA variants). Prenatal genetic testing for IL10R-defects is feasible, yet the legal and ethical considerations are complex and controversial. In some countries, predictive genetics for IL-10-related signalling defects is entering clinical practice.

Ethical, Legal and Social Issues (ELSI) Associated with Non-Invasive Prenatal Testing: Reflections on the Evolution of Prenatal Diagnosis and Procreative Choices.

New technologies such as non-invasive prenatal testing (NIPT), capable of analyzing cell-free fetal DNA in the maternal bloodstream, have become increasingly widespread and available, which has in turn led to ethical and policy challenges that need addressing. NIPT is not yet a diagnostic tool, but can still provide information about fetal genetic characteristics (including sex) very early in pregnancy, and there is no denying that it offers valuable opportunities for pregnant women, particularly those at high risk of having a child with severe genetic disorders or seeking an alternative to invasive prenatal testing. Nonetheless, the ethical, legal and social implications (ELSI) include multiple aspects of informed decision-making, which can entail risks for the individual right to procreative autonomy, in addition to the potential threats posed by sex-selective termination of pregnancy (in light of the information about fetal sex within the first trimester), and the stigmatization and discrimination of disabled individuals. After taking such daunting challenges into account and addressing NIPT-related medicolegal complexities, the review’s authors highlight the need for an ethically and legally sustainable framework for the implementation of NIPT, which seems poised to become a diagnostic tool, as its scope is likely to broaden in the near future.

Ocular abnormalities in patients with beta-thalassemia: a prospective study

<p><strong>Background: </strong>Beta thalassemia is severe genetic blood disorder caused by mutation in the gene encoding for the beta chains of haemoglobin and individuals with beta thalassemia require life-long red blood cell transfusions to survive which leads to hemosiderosis and affects all the organs in the body including eyes. The study aims to study ocular manifestations in these children and its correlation with age and serum ferritin levels.</p><p><strong>Methods: </strong>A descriptive cross-sectional study was done in government medical college Jammu in 2014-2015 on 67 BTM children. Children below 3 years of age and with pre-existing ocular abnormalities, infections were excluded from the study. Ocular examination was done for any major eye abnormality, congenital malformations or trauma. Retinal examination was done using direct and indirect ophthalmoscope, changes were recorded.</p><p><strong>Results: </strong>47.76% of children belonging to the group: 5-10 years, while only 5.97%, i.e., 4 in number pertained to the age group: >15 years. Lens opacity was seen in 29.85% of children. 31 children showed changes in retinal activity, while decreased visual acuity was also observed in 17 children. Iris was significantly affected in children with serum ferritin >2500 ng/ml. Even greater lenticular changes and opacities were observed in children with higher serum ferritin levels (>4500 ng/ml).</p><p><strong>Conclusions: </strong>As life expectancy for beta-thalassemia patients extends, regular monitoring of the progression of disease and symptoms to detect early changes in their ocular system is recommended, to achieve a better quality of life for this patient group.</p>

Correction of a urea cycle defect after ex vivo gene editing of human hepatocytes

Ornithine transcarbamylase deficiency (OTCD) is a monogenic disease of ammonia metabolism in hepatocytes. Severe disease is frequently treated by orthotopic liver transplantation. An attractive approach is the correction of a patient’s own cells to regenerate the liver with gene-repaired hepatocytes. This study investigates the efficacy and safety of ex vivo correction of primary human hepatocytes. Hepatocytes isolated from an OTCD patient were genetically corrected ex vivo, through the deletion of a mutant intronic splicing site achieving editing efficiencies >60% and the restoration of the urea cycle in vitro. The corrected hepatocytes were transplanted into the liver of FRGN mice and repopulated to high levels (>80%). Animals transplanted and liver repopulated with genetically edited patient hepatocytes displayed normal ammonia, enhanced clearance of an ammonia challenge and OTC enzyme activity, as well as lower urinary orotic acid when compared to mice repopulated with unedited patient hepatocytes. Gene expression was shown to be similar between mice transplanted with unedited or edited patient hepatocytes. Finally, a genome-wide screening by performing CIRCLE-seq and deep sequencing of >70 potential off-targets revealed no unspecific editing. Overall analysis of disease phenotype, gene expression, and possible off-target editing indicated that the gene editing of a severe genetic liver disease was safe and effective.

Associations between common genetic variants in microRNAs and Hirschsprung disease susceptibility in Southern Chinese children.

IntroductionHirschsprung disease (HSCR), characterized by the defective migration of enteric neural crest cells, is a severe congenital tract disease in infants. Its etiology is not clear at present, although a genetic component plays an important role in its etiology. Many studies focused on the polymorphisms of microRNA (miRNA) in several disease progressions have been reported, including HSCR. However, the findings remain inconclusive. The present study aimed to explore the association of genetic variants in miRNAs and HSCR susceptibility in Southern Chinese children.MethodsFive single nucleotide polymorphisms (SNPs) (miR‐146A rs2910164, miR‐4318 rs8096901, miR‐3142 rs2431697, miR‐3142 rs2431097 and miR‐3142 rs5705329) were included to be genotyped in the stratified analysis through the Mass ARRAY iPLEX Gold system (Sequenom, San Diego, CA, USA) conducted on all the samples, comprising 1470 cases and 1473 controls. After quality control, the minor allele frequency was compared in cases and controls to analyze the association between SNPs and HSCR using PLINK 1.9 (https://www.cog‐genomics.org/plink) and multiple heritability models were tested (additive, recessive and dominant models).ResultsOur results indicated that miR‐4318 rs8096901 polymorphisms were associated with HSCR susceptibility in Southern Chinese children, especially in short‐segment HSCR (S‐HSCR) patients after stratified analysis.ConclusionsIn summary, we report that miR‐4318 rs8096901 was associated with HSCR, especially in SHSCR patients.

Hierarchical Bayesian modelling of disease progression to inform clinical trial design in centronuclear myopathy

BackgroundCentronuclear myopathies are severe rare congenital diseases. The clinical variability and genetic heterogeneity of these myopathies result in major challenges in clinical trial design. Alternative strategies to large placebo-controlled trials that have been used in other rare diseases (e.g., the use of surrogate markers or of historical controls) have limitations that Bayesian statistics may address. Here we present a Bayesian model that uses each patient’s own natural history study data to predict progression in the absence of treatment. This prospective multicentre natural history evaluated 4-year follow-up data from 59 patients carrying mutations in the MTM1 or DNM2 genes.MethodsOur approach focused on evaluation of forced expiratory volume in 1 s (FEV1) in 6- to 18-year-old children. A patient was defined as a responder if an improvement was observed after treatment and the predictive probability of such improvement in absence of intervention was less than 0.01. An FEV1 response was considered clinically relevant if it corresponded to an increase of more than 8%.ResultsThe key endpoint of a clinical trial using this model is the rate of response. The power of the study is based on the posterior probability that the rate of response observed is greater than the rate of response that would be observed in the absence of treatment predicted based on the individual patient’s previous natural history. In order to appropriately control for Type 1 error, the threshold probability by which the difference in response rates exceeds zero was adapted to 91%, ensuring a 5% overall Type 1 error rate for the trial.ConclusionsBayesian statistical analysis of natural history data allowed us to reliably simulate the evolution of symptoms for individual patients over time and to probabilistically compare these simulated trajectories to actual observed post-treatment outcomes. The proposed model adequately predicted the natural evolution of patients over the duration of the study and will facilitate a sufficiently powerful trial design that can cope with the disease’s rarity. Further research and ongoing dialog with regulatory authorities are needed to allow for more applications of Bayesian statistics in orphan disease research.

Impact of photobiomodulation using four diode laser wavelengths of on cationic liposome gene transfection into pre-osteoblast cells

Gene therapy can be an effective treatment modality for some severe genetic diseases. Despite efforts to improve their performance, non-viral gene delivery methods remain inefficient and costly. As an alternative to viral vectors, cationic liposomes have a good safety profile and low immunogenicity, but relatively low transfection efficiency. They may also be toxic to cells at high concentrations. Given these challenges, the present study explored the impact of photobiomodulation (PBM) on cationic liposome plasmid DNA transfection in terms of its efficiency and toxicity, using Lipofectamine 2000 to carry green fluorescent protein (GFP) encoding plasmid DNA, with the pre-osteoblast MC3T3-E1 cell line as the target. Cultures were irradiated using diode lasers (445, 685, 810, or 970 nm) at 200 mW using pulsed mode (50 Hz), with a power density of 104.64 mW/cm2, and irradiance from 6 to 18 joules. To determine transfection efficiency, expression of GFP was assessed using confocal laser scanning microscopy and flow cytometry. Cell viability was evaluated using the MTT assay. PBM using 810 nm and 970 nm lasers significantly enhanced transfection efficiency for GFP, indicating more efficient uptake of plasmid DNA. Conversely, laser irradiation at 445 nm and 685 nm wavelengths reduced the GFP transfection efficiency. Treatment using 685, 810, and 970 nm lasers at 12 J maintained cell viability and prevented toxicity of cationic liposomes. Overall, these findings support the concept that PBM using near infrared laser wavelengths can enhance transfection efficiency and support cell viability when cationic liposomes are used as the vector in gene therapy.

First-in-Human Autologous Implantation of Genetically Modified Adipocytes Expressing LCAT for the Treatment of Familial LCAT Deficiency

Familial lecithin: cholesterol acyltransferase (LCAT) deficiency (FLD) is a severe inherited disease without a cure. Genetically modified adipocyte (GMAC) secreting LCAT (LCAT-GMAC) was developed to treat FLD. First-in-human autologous implantation of LCAT-GMACs was performed, showing to be safe and effective. The LCAT-GMAC implantation increased serum LCAT activity by approximately 50% of the baseline and sustained over three years. The patient exhibited apparent hemolysis by visual inspection. We found the presence of hemoglobin/haptoglobin complex in the patient's serum. The hemoglobin-haptoglobin complex was almost disappeared seven days after the implantation. Upon implantation of LCAT-GMAC, the patient's proteinuria decreased temporarily to mild levels and then gradually increased to the baseline. At 48 weeks after implantation, proteinuria deteriorated with the development of mild hypertension. To treat hypertension, the patient received antihypertensives, leading to the normalization of blood pressure. With the reduction of blood pressure, the proteinuria rapidly decreased to mild proteinuria levels. Trial registration: registered in Japan Registry of Clinical Trials: jRCTa030190230 Ethics: Approved by the Ministry of Health, Labour, and Welfare of Japan Funding: This research was supported by Japan Agency for Medical Research and Development (AMED) to M. A. under Grant Number JP 17im0110606h0004 Conflict of Interests: None.

Adolescente com síndrome de Edwards: relato de um caso raro

Edwards’ syndrome is a severe genetic disease (chromosome 18 trisomy) that has a very restrict prognosis, resulting in premature death of the carrier. This study aims to report a case of survival of 12 years old girl diagnosed in the first months of life, her clinical evolution and the treatments performed by it. The multidisciplinary treatment performed by the adolescent since the first months of life shows the importance of this approach to improve the quality of life of patients with this syndrome.

Beleaguered Bluebird's New CEO Charts Comeback Course with “Zero Distractions”

GEN EdgeVol. 3, No. 1 Genome EditingBeleaguered Bluebird's New CEO Charts Comeback Course with “Zero Distractions”Following the spin-off of Bluebird's oncology programs into 2Seventy bio, Bluebird CEO Andrew Obenshain addresses his company's focus on severe genetic disease and his steadfast belief in lentiviral vectorsAlex PhilippidisAlex PhilippidisSearch for more papers by this authorPublished Online:15 Nov 2021https://doi.org/10.1089/genedge.3.1.112AboutSectionsView articleView Full TextPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail View articleFiguresReferencesRelatedDetails Volume 3Issue 1Jan 2021 Information© 2021 by GEN PublishingTo cite this article:Alex Philippidis.Beleaguered Bluebird's New CEO Charts Comeback Course with “Zero Distractions”.GEN Edge.Jan 2021.673-680.http://doi.org/10.1089/genedge.3.1.112Published in Volume: 3 Issue 1: November 15, 2021PDF download

European Perspectives on Regulation of Heritable Genome-editing

New developments in genome editing techniques, such as CRISPR/Cas9, have raised significant questions before humankind. The promise of CRISPR /Cas9 lies in the ability to make precise edits in the human genome which may help prevent progeny from being born with severe genetic diseases. At the same time there are significant risks because we do not yet know about the safety of this technique or what its long-term effects are going to be. Also legitimate is the concern about potential for misuse for eugenic purposes. The scientific community is split on the question of whether research in this area should continue. This article explores answers for some of these questions in law applicable in Europe. I also attempt to answer the nagging question - if allowed to be performed, would such a technique be compliant with human dignity?

Compensatory and adaptive mechanisms in children with congenital multiple arthrogryposis in the absence of active flexion in the elbow joint

To study the compensatory strategies in children with arthrogryposis with absent of active flexion in the elbow joint and estimate their dynamic after surgical treatment. We performed a clinical examination of 236 patients with arthrogryposis with deformities of the upper extremities due to arthrogryposis at the age of 10 months to 16 years. The examination was carried out before the operation, as well as at various times (from 1 month to 8 years) after. In 87 cases (67 patients), restoration of active elbow flexion was performed by transposition of latissimus dorsii or pectoralis major to the biceps position. The activity of the muscles involved that most commonly used in compensatory strategies (synergy of m. biceps brachii and m. deltoideus or m.biceps brachii and m. quadriceps femoris) in 10 patients (from 3 to 10 y.o.), was evaluated before and after (from 2 months to 2 years) surgery by surface electromyography. It was found that children's compensatory strategies are formed at the age of 6 months to 1 y.o.6 months after surgery, the using of compensatory strategies becomes more rare, and 12-18 months after surgery, when the strength of the forearm muscles was 4 points, they were not used at all. Compensatory strategies in children with the absence of active and preservation of passive flexion in the elbow joint are diverse. They depend on the amplitude of passive and active movements in the shoulder, the function of the hand and deformities of the lower extremities. These strategies in children with arthrogryposis are unstable and completely disappear when active movements in the elbow joint are restored in the functional range.

Cardiac K+ Channels and Channelopathies.

The physiological heart function is controlled by a well-orchestrated interplay of different ion channels conducting Na+, Ca2+ and K+. Cardiac K+ channels are key players of cardiac repolarization counteracting depolarizating Na+ and Ca2+ currents. In contrast to Na+ and Ca2+, K+ is conducted by many different channels that differ in activation/deactivation kinetics as well as in their contribution to different phases of the action potential. Together with modulatory subunits these K+ channel α-subunits provide a wide range of repolarizing currents with specific characteristics. Moreover, due to expression differences, K+ channels strongly influence the time course of the action potentials in different heart regions. On the other hand, the variety of different K+ channels increase the number of possible disease-causing mutations. Up to now, a plethora of gain- as well as loss-of-function mutations in K+ channel forming or modulating proteins are known that cause severe congenital cardiac diseases like the long-QT-syndrome, the short-QT-syndrome, the Brugada syndrome and/or different types of atrial tachyarrhythmias. In this chapter we provide a comprehensive overview of different K+ channels in cardiac physiology and pathophysiology.

Reverse Phase-high-performance Liquid Chromatography (RP-HPLC) Analysis of Globin Chains from Human Erythroid Cells

β-hemoglobinopathies are severe genetic disorders characterized either by the abnormal synthesis of the adult β-globin chains of the hemoglobin (Hb) tetramer (βS-globin chains) in sickle cell disease (SCD) or by the reduced β-globin production in β-thalassemia. The identification and quantification of globin chains are crucial for the diagnosis of these diseases and for testing new therapeutic approaches aimed at correcting the β-hemoglobinopathy phenotype. Conventional techniques to detect the different Hb molecules include cellulose-acetate electrophoresis (CEA), capillary electrophoresis (CE), isoelectric focusing (IEF), and cation-exchange-HPLC (CE-HPLC). However, these methods cannot distinguish the different globin chains and precisely determine their relative expression. We have set up a high-resolution and reproducible reverse phase-HPLC (RP-HPLC) to detect and identify the globin chains composing the hemoglobin tetramers based on their different hydrophobic properties. RP-HPLC mobile phases are composed of acetonitrile (ACN) that creates a hydrophobic environment and trifluoroacetic acid (TFA), which breaks the heme group within the Hb tetramers releasing individual globin chains. Hb-containing lysates are loaded onto the AerisTM 3.6-µm WIDEPORE C4 200 Å LC Column and a gradient of increasing hydrophobicity of the mobile phase over time allows globin chain separation. The relative amount of globin chains is measured at a wavelength (λ) of 220 nm. This protocol is designed for evaluating globin chains in (i) red blood cells (RBCs) obtained from human peripheral blood, (ii) RBCs in vitro differentiated from hematopoietic stem/progenitor cells (HSPCs), and (iii) burst-forming unit-erythroid (BFU-E), i.e., erythroid progenitors obtained in vitro from human peripheral blood or in vitro cultured HSPCs. This technique allows to precisely identify the different globin chains and obtain a relative quantification. RP-HPLC can be used to confirm the diagnosis of β-hemoglobinopathies, to evaluate the disease severity and validate novel approaches for the treatment of these diseases.

Recent Advances and Machine Learning Techniques on Sickle Cell Disease

Sickle cell disease is a severe hereditary disease caused by an abnormality of the red blood cells. The current therapeutic decision-making process applied to sickle cell disease includes monitoring a patient’s symptoms and complications and then adjusting the treatment accordingly. This process is time-consuming, which might result in serious consequences for patients’ lives and could lead to irreversible disease complications. Artificial intelligence, specifically machine learning, is a powerful technique that has been used to support medical decisions. This paper aims to review the recently developed machine learning models designed to interpret medical data regarding sickle cell disease. To propose an intelligence model, the suggested framework has to be performed in the following sequence. First, the data is preprocessed by imputing missing values and balancing them. Then, suitable feature selection methods are applied, and different classifiers are trained and tested. Finally, the performing model with the highest predefined performance metric over all experiments conducted is nominated. Thus, the aim of developing such a model is to predict the severity of a patient’s case, to determine the clinical complications of the disease, and to suggest the correct dosage of the treatment(s).

A novel chromosome cluster types identification method using ResNeXt WSL model.

Chromosome karyotyping analysis plays a crucial role in prenatal diagnosis for diagnosing whether a fetus has severe defects or genetic diseases. However, due to the complicated morphological characteristics of various types of chromosome clusters, chromosome instance segmentation is the most challenging stage of chromosome karyotyping analysis, leading chromosome karyotyping analysis to highly dependent on skilled clinical analysts. Since most of the chromosome instance segmentation efforts are currently devoted to segmenting chromosome instances from different types of chromosome clusters, type identification of chromosome clusters is a vital anterior task for chromosome instance segmentation. Firstly, this paper proposes an automatic approach for chromosome cluster identification using recent transfer learning techniques. The proposed framework is based on ResNeXt weakly-supervised learning (WSL) pre-trained backbone and a task-specific network header. Secondly, this paper proposes a fast training methodology that tunes our framework from coarse-to-fine gradually. Extensive evaluations on a clinical dataset consisting of 6592 clinical chromosome samples show that the proposed framework achieves 94.09%accuracy, 92.79%sensitivity, and 98.03%specificity. Such performance is superior to the best baseline model that we obtain 92.17%accuracy, 89.1%sensitivity, and 97.42%specificity. To foster research and application in the chromosome cluster type identification, we make our clinical dataset and code available via GitHub.

Induced Pluripotent Stem Cells to Understand Mucopolysaccharidosis. I: Demonstration of a Migration Defect in Neural Precursors

Background: Mucopolysaccharidosis type I-Hurler (MPS1-H) is a severe genetic lysosomal storage disorder due to loss-of-function mutations in the IDUA gene. The subsequent complete deficiency of alpha l-iduronidase enzyme is directly responsible of a progressive accumulation of glycosaminoglycans (GAG) in lysosomes which affects the functions of many tissues. Consequently, MPS1 is characterized by systemic symptoms (multiorgan dysfunction) including respiratory and cardiac dysfunctions, skeletal abnormalities and early fatal neurodegeneration. Methods: To understand mechanisms underlying MPS1 neuropathology, we generated induced pluripotent stem cells (iPSC) from a MPS1-H patient with loss-of-function mutations in both IDUA alleles. To avoid variability due to different genetic background of iPSC, we established an isogenic control iPSC line by rescuing IDUA expression by a lentivectoral approach. Results: Marked differences between MPS1-H and IDUA-corrected isogenic controls were observed upon neural differentiation. A scratch assay revealed a strong migration defect of MPS1-H cells. Also, there was a massive impact of IDUA deficiency on gene expression (340 genes with an FDR < 0.05). Conclusions: Our results demonstrate a hitherto unknown connection between lysosomal degradation, gene expression and neural motility, which might account at least in part for the phenotype of MPS1-H patients.