Genome Sequencing Techniques Research Articles

Whole genome strategies and bioremediation insight into dehalogenase-producing bacteria.

An integral approach to decoding both culturable and uncultured microorganisms' metabolic activity involves the whole genome sequencing (WGS) of individual/complex microbial communities. WGS of culturable microbes, amplicon sequencing, metagenomics, and single-cell genome analysis are selective techniques integrating genetic information and biochemical mechanisms. These approaches transform microbial biotechnology into a quick and high-throughput culture-independent evaluation and exploit pollutant-degrading microbes. They are windows into enzyme regulatory bioremediation pathways (i.e., dehalogenase) and the complete bioremediation process of organohalide pollutants. While the genome sequencing technique is gaining the scientific community's interest, it is still in its infancy in the field of pollutant bioremediation. The techniques are becoming increasingly helpful in unraveling and predicting the enzyme structure and explore metabolic and biodegradation capabilities.

COVID-19 outbreak in Malaysia: Decoding D614G mutation of SARS-CoV-2 virus isolated from an asymptomatic case in Pahang

SARS-CoV-2 is a very transmissible and pathogenic coronavirus which detected in Malaysia in January 2020. Nevertheless, the sample from Malaysia is still under-sequenced. Hence lacking clarity of the circulating strain in Malaysia leads to a deadlock in understanding the virus infectivity. This study aimed to investigate the genome identity of circulating COVID-19 strains in Pahang and understand disease epidemiology during the pandemic. This study leveraged high-throughput sequencing analysis for the whole genome sequencing and implemented bioinformatic technique for the analysis. Here we reported that the virus with D614G mutation in Spike protein circulates in a few Malaysia states before the Sivagangga cluster announced in Kedah in July 2020. This mutated virus includes our virus sample isolated in April 2020 from an asymptomatic patient in Pahang. Based on the phylogenetic analysis, we discovered the origin of our sample Pahang/IIUM91 was not related to Sivagangga cluster. Here, we have generated 3D structure model of Pahang/IIUM91 Spike protein. D614G mutation in Pahang/IIUM91 Spike protein increases viral stability and flexibility, hence render higher infectivity. Collectively, our results suggest for the establishment of a complete SARS-CoV-2 genome database in Malaysia. Hence, more research should be established to learn the behaviour of this virus.

RAD: a web application to identify region associated differentially expressed genes.

With the advance of genomic sequencing techniques, chromatin accessible regions, transcription factor binding sites and epigenetic modifications can be identified at genome-wide scale. Conventional analyses focus on the gene regulation at proximal regions; however, distal regions are usually less focused, largely due to the lack of reliable tools to link these regions to coding genes. In this study, we introduce RAD (Region Associated Differentially expressed genes), a user-friendly web tool to identify both proximal and distal region associated differentially expressed genes (DEGs). With DEGs and genomic regions of interest (gROI) as input, RAD maps the up- and down-regulated genes associated with any gROI and helps researchers to infer the regulatory function of these regions based on the distance of gROI to differentially expressed genes. RAD includes visualization of the results and statistical inference for significance. RAD is implemented with Python 3.7 and run on a Nginx server. RAD is freely available at https://labw.org/rad as online web service. Supplementary data are available at Bioinformatics online.

Genome-Wide Identification of Cis-acting Expression QTLs in Large Yellow Croaker.

The large yellow croaker is one of the largest marine economic fish in China with the farming yield about 30 tons per year. The genetic selection for growth and disease resistance has been performed in recent years. The identification of trait-associated molecular makers, causative variants, and causative genes is helpful for genetic selection in large yellow croaker. It has been discovered that most of polygenic traits are controlled with multiple genes via regulatory variant, and GWAS-identified loci are enriched in the regulatory variant. Cis-acting eQTL is a widespread regulatory variant that controls the expression of nearby gene.We herein take advantage of RNA-seq and whole genome sequencing technique to identify genome-wide eQTLs in liver tissue for large yellow croaker; a forward selection routine is applied for identification of multiple eQTLs. To fine map causative mutation for each eQTL, a credible set is built to confine causative variants. Totally, 2427 eQTLs have been identified, 69.7% (1,691/2,427) of them are primary eQTL signals, and the remaining are secondary signals, many functional important target genes have been discovered. We highlight several functional pivotal genes including SMC3, TUSC3, TITIN, MCPH1, and MDHC, in which the expression of MCPH1 is regulated by two eQTLs; the distance of these eQTLs from target genes is symmetrically distributed, 25.5% of them are within 1Mb region from target genes, whereas 74.5% of them are between 1 and 2Mb regions; most of the identified eQTL has been well resolved, and 19.3 (469/2427) of eQTL have the size of credible set (the number of variants in credible set) less than 50.

Evaluation of analytical protocols of alignment mapping tools using high throughput next-generation genome sequencing data

Background: Ever since the development of first next-generation genome sequencer (NGS) in 2005, there are rapid developments of high throughput next-generation genome sequencing (HT-NGS) techniques and tools used in genetics and genomics has become much more comfortable and cheaper. The result is the generation of a massive amount of data sets, requiring detailed analysis, which becomes impossible without the use of appropriate bioinformatics tools. One of the crucial steps in the analysis of NGS data is to map readings to a reference sequence. Although the dominance of Illumina synthesis by sequencing (SBS) technology has been noticeable in recent years, the choice of the tools is hampered and the variety of input data and reference genomes. Moreover, the tools used are crucial for result files and further analysis.Methods: The subject of this paper is the three most frequently used alignment mapping programs, which have functions to allow working with many platforms: BWA, Bowtie2 and SMALT. The task of the tested aligners is to match short sequences coming from NGS with reference sequences. The most popular: BWA and Bowtie2 use for this purpose the Burrows-Wheeler transformation and SMALT maps the sequences using hashing and dynamic programming. The presented paper aimed to compare the quality and efficiency of the alignment mapping programs under examination, due to three criteria: i) the quality of the compared sequences of different lengths and from different platforms; ii) coefficient of wrongly compared sequences; iii) the computational resources used.Results: By comparing the results of the mapping analyses for all the programs used, the least popular SMALT is the best. Obtaining the highest percentage of mapped readings for each platform and maintaining the lowest computational memory usage, turns out to be the most optimal choice.Conclusions: The results presented in this paper can be used to verify and rebuild data analysis pipelines from NGS based so far on other tools. We conclude that by using the tools under appropriate conditions, it is possible to improve the quality of the analyses, speed them up and reduce their cost.

Unidirectional mating-type switching confers self-fertility to Thielaviopsis cerberus, the only homothallic species in the genus

Sexual reproduction is ubiquitous in nature, and nowhere is this more so than in the fungi. Heterothallic behaviour is observed when there is a strict requirement of contact between two individuals of opposite mating type for sexual reproduction to occur. In contrast, a homothallic species can complete the entire sexual cycle in isolation, although several genetic mechanisms underpin this self-fertility. These can be inferred by characterising the structure and gene-content of the mating-type locus, which contains genes that are involved in the regulation of sexual reproduction. In this study, the genetic basis of homothallism in Thielaviopsis cerberus was investigated, the only known self-fertile species within this genus. Using genome sequencing and conventional molecular techniques, two versions of the mating-type locus were identified in this species. This is typical of species that have a unidirectional mating-type switching reproductive strategy. The first version was a self-fertile locus that contained four known mating-type genes, while the second was a self-sterile version with a single mating-type gene. The conversion from a self-fertile to a self-sterile locus is likely mediated by a homologous recombination event at two direct repeats present in the self-fertile locus, resulting in the deletion of three mating-type genes and one of the repeats. Both locus versions were present in isolates that were self-fertile, while self-sterility was caused by the presence of only a switched locus. This study provides a clear example of the architectural fluidity in the mating-type loci that is common among even closely related fungal species.

Meduloblastoma pediatrikoaren pronostikorako markatzaile molekularren identifikazioa

Meduloblastoma klinika eta oinarri molekular heterogeneoa duen minbizia da. Azken urteotan, genoma osoko eta sekuentziazio masiboko teknika molekularren garapenaren ondorioz, meduloblastoma pediatrikoan parte hartzen duten mutazio asko identifikatzea ahalbidetu da. Hortaz, lanaren helburua izan zen meduloblastoma pediatrikoaren pronostikoan edota terapian lagundu dezakeen gene eta mutazio somatikoen panel baten diseinua egitea. Horretarako, meduloblastoma pediatrikoan eragina duten geneei buruzko informazioa duen literaturaren berrikuspen sistematikoa egin zen. Bilaketarako Pubmed datubase bibliografikoa erabili zen, honako termino hauek erabiliz: (Medulloblastoma*) AND («mutation*» OR «genetic alteration*» OR «genetic variation*»). Berrikuspen bibliografikoaren ondoren, hasieran zeuden 588 artikuluetatik 62 artikulutan 197 gene identifikatu ziren. Horietatik, % 2 baino gehiagoko mutazio-maiztasuna zuten 21 gene aurkitu ziren, eta diagnosiaren momentuan balio pronostikoa edo meduloblastoma azpimoten ezaugarri ziren 5 gene (TP53, CTNNB1, PTCH1, SUFU eta KDM6A). Gene horiek analizatuz gero, profil molekularrean oinarritutako tratamendu indibidualizatuak doitu litezke.

Functional Metagenomics for Identification of Antibiotic Resistance Genes (ARGs).

The identification of antibiotic resistance genes (ARGs) in microbial communities is one of the most challenging tasks in biology. The evolution and improvement of genome sequencing techniques, combined with the improvement of computational analysis techniques, have allowed us to acquire increasingly detailed information on the complex and varied microbial community that coexists and coevolves in the most heterogeneous environment. This chapter describes how to identify and quantify ARGs, using specific tools (Bowtie2, Bedtools for coverage, G/C content, and theestimatednumber of reads mapping each open reading frame; RGI tool, with the support of CARD database, to inspect the distribution of antibiotic resistance genes). Once this information is obtained, scientists would be able to highlight the relative abundance of ARGs in the metagenome analyzed and be able to understand how antibiotic resistance mechanisms evolve in microbial communities.

Multipartite Genome of Lyme Disease Borrelia: Structure, Variation and Prophages.

All members of the Borrelia genus that have been examined harbour a linear chromosome that is about 900 kbp in length, as well as a plethora of both linear and circular plasmids in the 5-220 kbp size range. Genome sequences for 27 Lyme disease Borrelia isolates have been determined since the elucidation of the B. burgdorferi B31 genome sequence in 1997. The chromosomes, which carry the vast majority of the housekeeping genes, appear to be very constant in gene content and organization across all Lyme disease Borrelia species. The content of the plasmids, which carry most of the genes that encode the differentially expressed surface proteins that interact with the spirochete's arthropod and vertebrate hosts, is much more variable. Lyme disease Borrelia isolates carry between 7-21 different plasmids, ranging in size from 5-84 kbp. All strains analyzed to date harbor three plasmids, cp26, lp54 and lp17. The plasmids are unusual, as compared to most bacterial plasmids, in that they contain many paralogous sequences, a large number of pseudogenes, and, in some cases, essential genes. In addition, a number of the plasmids have features indicating that they are prophages. Numerous methods have been developed for Lyme disease Borrelia strain typing. These have proven valuable for clinical and epidemiological studies, as well as phylogenomic and population genetic analyses. Increasingly, these approaches have been displaced by whole genome sequencing techniques. Some correlations between genome content and pathogenicity have been deduced, and comparative whole genome analyses promise future progress in this arena.

Adult precision medicine: learning from the past to enhance the future.

Despite therapeutic advances for other malignancies, gliomas remain challenging solid tumors to treat. Complete surgical resection is nearly impossible due to gliomas’ diffuse infiltrative nature, and treatment is hampered by restricted access to the tumors due to limited transport across the blood–brain barrier. Recent advances in genomic studies and next-generation sequencing techniques have led to a better understanding of gliomas and identification of potential aberrant signaling pathways. Targeting the specific genomic abnormalities via novel molecular therapies has opened a new avenue in the management of gliomas, with encouraging results in preclinical studies and early clinical trials. However, molecular characterization of gliomas revealed significant heterogeneity, which poses a challenge for targeted therapeutic approaches. In this context, leading neuro-oncology researchers and clinicians, industry innovators, and patient advocates convened at the inaugural annual Remission Summit held in Orlando, FL in February 2019 to discuss the latest advances in immunotherapy and precision medicine approaches for the treatment of adult and pediatric brain tumors and outline the unanswered questions, challenges, and opportunities that lay ahead for advancing the duration and quality of life for patients with brain tumors. Here, we provide historical context for precision medicine in other cancers, present emerging approaches for gliomas, discuss their limitations, and outline the steps necessary for future success. We focus on the advances in small molecule targeted therapy, as the use of immunotherapy as an emerging precision medicine modality for glioma treatment has recently been reviewed by our colleagues.

Application of targeted genome sequencing to brain metastasis from non-small cell lung carcinoma: Case report

Non-small cell lung cancer (NSCLC) is frequently associated with central nervous system metastases resulting in poor outcomes. As newer targeted therapies become available determining which patients can benefit from these therapies has remained challenging, and current molecular testing options rely on a panel of only a handful of known oncogenic drivers. Here, we demonstrate a targeted approach at uncovering clinically relevant variants in cancer-associated genes using genomic sequencing. Our patient underwent targeted sequencing of 212 cancer-associated genes, revealing mutations in six; two of which were in EGFR, an important target for therapy in NSCLC. A multidisciplinary approach involving surgical resection, radiation, and targeted therapy based on the genomic profile and tumor pathology ultimately lead to positive therapeutic response and stable disease. Our report provides a proof of principle for incorporating higher throughput genomic sequencing techniques directly into patient care. We also report an atypical response of an EGFR mutation positive metastatic tumor to immune checkpoint therapy, despite recent reports suggesting that these patients do not benefit from immune checkpoint inhibitors. A brief review of current literature is discussed here to explore links between EGFR mutations and PD-L1 expression, as well as response to targeted therapies.

From ecophysiology to cultivation methodology: filling the knowledge gap between uncultured and cultured microbes.

Earth is dominated by a myriad of microbial communities, but the majority fails to grow under in situ laboratory conditions. The basic cause of unculturability is that bacteria dominantly occur as biofilms in natural environments. Earlier improvements in the culture techniques are mostly done by optimizing media components. However, with technological advancement particularly in the field of genome sequencing and cell imagining techniques, new tools have become available to understand the ecophysiology of microbial communities. Hence, it becomes easier to mimic environmental conditions in the culture plate. Other methods include co-culturing, emendation of growth factors, and cultivation after physical cell sorting. Most recently, techniques have been proposed for bacterial cultivation by employing genomic data to understand either microbial interactions (network-directed targeted bacterial isolation) or ecosystem engineering (reverse genomics). Hopefully, these techniques may be applied to almost all environmental samples, and help fill the gaps between the cultured and uncultured microbial communities.

Genomic Comparison and Spatial Distribution of Different Synechococcus Phylotypes in the Black Sea.

Picocyanobacteria of the genus Synechococcus are major contributors to global primary production and nutrient cycles due to their oxygenic photoautotrophy, their abundance, and the extensive distribution made possible by their wide-ranging biochemical capabilities. The recent recovery and isolation of strains from the deep euxinic waters of the Black Sea encouraged us to expand our analysis of their adaptability also beyond the photic zone of aquatic environments. To this end, we quantified the total abundance and distribution of Synechococcus along the whole vertical profile of the Black Sea by flow cytometry, and analyzed the data obtained in light of key environmental factors. Furthermore, we designed phylotype-specific primers using the genomes of two new epipelagic coastal strains – first described here – and of two previously described mesopelagic strains, analyzed their presence/abundance by qPCR, and tested this parameter also in metagenomes from two stations at different depths. Together, whole genome sequencing, metagenomics and qPCR techniques provide us with a higher resolution of Synechococcus dynamics in the Black Sea. Both phylotypes analyzed are abundant and successful in epipelagic coastal waters; but while the newly described epipelagic strains are specifically adapted to this environment, the strains previously isolated in mesopelagic waters are able, in low numbers, to withstand the aphotic and oxygen depleted conditions of deep layers. This heterogeneity allows different Synechococcus phylotypes to occupy different niches and underscores the importance of a more detailed characterization of the abundance, distribution, and dynamics of individual populations of these picocyanobacteria.

Identification of bacteria-derived urease in the coral gastric cavity

Nitrogen cycle is critical to maintain a healthy coral reef ecosystem. Urea can provide a source of nitrogen for coral holobiont and is important for coral calcification through degradation by urease. Despite the involvement of coral-associated bacteria in nitrogen fixation, nitrification and denitrification are well recognized, to what extend urea degradation by bacteria contributing to the urea utilization by coral holobiont remains to be investigated. In this study, we demonstrate that the urea utilization is a common feature of Halomonas spp. that is a dominant genus in cultivable coral-associated bacteria. A urease operon was characterized by genome sequencing and gene knock-out technique in Halomonas meridiana SCSIO 43005, isolated from the gastric cavity of healthy scleractinian coral Galaxea fascicularis. H. meridiana showed high urease activity which was induced by urea and deletion of the urease operon reduced the capability to use urea as solo nitrogen source. Furthermore, approximately 1/3 coral-associated bacteria in the IMG/M database possess complete urease operons indicating the involvement of bacteria-derived ureases in coral holobiont. These results suggest that urease from coral-associated bacteria might be important player in the nitrogen cycling of coral reefs.

Rapid Phenotype-Driven Gene Sequencing with the NeoSeq Panel: A Diagnostic Tool for Critically Ill Newborns with Suspected Genetic Disease.

New genomic sequencing techniques have shown considerable promise in the field of neonatology, increasing the diagnostic rate and reducing time to diagnosis. However, several obstacles have hindered the incorporation of this technology into routine clinical practice. We prospectively evaluated the diagnostic rate and diagnostic turnaround time achieved in newborns with suspected genetic diseases using a rapid phenotype-driven gene panel (NeoSeq) containing 1870 genes implicated in congenital malformations and neurological and metabolic disorders of early onset (<2 months of age). Of the 33 newborns recruited, a genomic diagnosis was established for 13 (39.4%) patients (median diagnostic turnaround time, 7.5 days), resulting in clinical management changes in 10 (76.9%) patients. An analysis of 12 previous prospective massive sequencing studies (whole genome (WGS), whole exome (WES), and clinical exome (CES) sequencing) in newborns admitted to neonatal intensive care units (NICUs) with suspected genetic disorders revealed a comparable median diagnostic rate (37.2%), but a higher median diagnostic turnaround time (22.3 days) than that obtained with NeoSeq. Our phenotype-driven gene panel, which is specific for genetic diseases in critically ill newborns is an affordable alternative to WGS and WES that offers comparable diagnostic efficacy, supporting its implementation as a first-tier genetic test in NICUs.

Fatal Perinatal Mitochondrial Cardiac Failure Caused by Recurrent De Novo Duplications in the ATAD3 Locus

In about half of all patients with a suspected monogenic disease, genomic investigations fail to identify the diagnosis. A contributing factor is the difficulty with repetitive regions of the genome, such as those generated by segmental duplications. The ATAD3 locus is one such region, in which recessive deletions and dominant duplications have recently been reported to cause lethal perinatal mitochondrial diseases characterized by pontocerebellar hypoplasia or cardiomyopathy, respectively. Whole exome, whole genome and long-read DNA sequencing techniques combined with studies of RNA and quantitative proteomics were used to investigate 17 subjects from 16 unrelated families with suspected mitochondrial disease. We report six different de novo duplications in the ATAD3 gene locus causing a distinctive presentation including lethal perinatal cardiomyopathy, persistent hyperlactacidemia, and frequently corneal clouding or cataracts and encephalopathy. The recurrent 68 Kb ATAD3 duplications are identifiable from genome and exome sequencing but usually missed by microarrays. The ATAD3 duplications result in the formation of identical chimeric ATAD3A/ATAD3C proteins, altered ATAD3 complexes and a striking reduction in mitochondrial oxidative phosphorylation complex I and its activity in heart tissue. ATAD3 duplications appear to act in a dominant-negative manner and the de novo inheritance infers a low recurrence risk for families, unlike most pediatric mitochondrial diseases. More than 350 genes underlie mitochondrial diseases. In our experience the ATAD3 locus is now one of the five most common causes of nuclear-encoded pediatric mitochondrial disease but the repetitive nature of the locus means ATAD3 diagnoses may be frequently missed by current genomic strategies. Australian NHMRC, US Department of Defense, Japanese AMED and JSPS agencies, Australian Genomics Health Alliance and Australian Mito Foundation.

Péritonite à Capnocytophaga spp. en dialyse péritonéale automatisée : à propos d’un cas

IntroductionCapnocytophaga spp. is a slow-growing bacterium that forms a part of the normal oral flora of dogs and cats. In peritoneal dialysis, only seven cases have been reported. We report the observation of a case of peritonitis with Capnocytophaga spp. in a patient on peritoneal dialysis who lives with a cat. Case reportA 64-year-old woman with chronic end stage renal disease due to chronic interstitial nephropathy on automated peritoneal dialysis has been admitted for diffuse abdominal pain. The dialysis fluid was cloudy with 11,250 elements/mm3, of leukocytes. Direct examination was negative. The C-reactive protein was 165mg/L. Intraperitoneal probabilistic antibiotic therapy was initiated 1g of cefazolin and 1g of ceftazidime per day. After eight days, aerobic culture was negative, the anaerobic one was positive to gram negative bacilli, but the identification could not be possible with MALDI-TOF mass spectrometry. Antibiotic therapy was continued by ceftazidime for 21 days. The evolution was marked by the improvement of the clinical and biological state of the patient. The germ was finally identified using the genomic 16S rRNA sequencing technique. This is Capnocytophaga spp. Investigation then revealed that the patient's cat sometimes entered her room at the time of connection of peritoneal dialysis. ConclusionThe case of our patient once again reveals the diagnostic difficulties posed by Capnocytophaga spp. Innovative techniques, such as MALDI-TOF-MS or genomic sequencing of ribosomal RNA, should be further used in peritoneal dialysis in the diagnosis of peritonitis.

Sequencing smart: De novo sequencing and assembly approaches for a non-model mammal.

BackgroundWhilst much sequencing effort has focused on key mammalian model organisms such as mouse and human, little is known about the relationship between genome sequencing techniques for non-model mammals and genome assembly quality. This is especially relevant to non-model mammals, where the samples to be sequenced are often degraded and of low quality. A key aspect when planning a genome project is the choice of sequencing data to generate. This decision is driven by several factors, including the biological questions being asked, the quality of DNA available, and the availability of funds. Cutting-edge sequencing technologies now make it possible to achieve highly contiguous, chromosome-level genome assemblies, but rely on high-quality high molecular weight DNA. However, funding is often insufficient for many independent research groups to use these techniques. Here we use a range of different genomic technologies generated from a roadkill European polecat (Mustela putorius) to assess various assembly techniques on this low-quality sample. We evaluated different approaches for de novo assemblies and discuss their value in relation to biological analyses.ResultsGenerally, assemblies containing more data types achieved better scores in our ranking system. However, when accounting for misassemblies, this was not always the case for Bionano and low-coverage 10x Genomics (for scaffolding only). We also find that the extra cost associated with combining multiple data types is not necessarily associated with better genome assemblies.ConclusionsThe high degree of variability between each de novo assembly method (assessed from the 7 key metrics) highlights the importance of carefully devising the sequencing strategy to be able to carry out the desired analysis. Adding more data to genome assemblies does not always result in better assemblies, so it is important to understand the nuances of genomic data integration explained here, in order to obtain cost-effective value for money when sequencing genomes.

Genetic mechanisms of antibiotic resistance and virulence in Acinetobacter baumannii: background, challenges and future prospects.

With the advent of the multidrug-resistant era, many opportunistic pathogens including the species Acinetobacter baumannii have gained prominence and pose a major global threat to clinical health care. Pathogenicity in bacteria is genetically regulated by a complex network of transcription and virulence factors and a brief overview of the major investigations on comprehending these processes over the past few decades in A. baumanni are compiled here. Many investigators have employed genome sequencing techniques to identify the regions that contribute to antibiotic resistance and comparative genomics to study sequence similarities to understand evolutionary trends of resistance gene transfers between isolates. A summary of these studies given here provides an insight into the invasion and successful colonization of the species. The individual roles played by different genes, regulators & promoters, enzymes, metal ions as well as mobile elements in influencing antibiotic resistance are briefly discussed. Precautionary measures and prospects for developing future strategies by exploring promising new research targets in effective control of multidrug resistant A. baumannii are also analyzed.

Acquired Aplastic Anemia as a Clonal Disorder of Hematopoietic Stem Cells

Aplastic anemia is rare disorder presenting with bone marrow failure syndrome due to autoimmune destruction of early hematopoietic stem cells (HSCs) and stem cell progenitors. Recent advances in newer genomic sequencing and other molecular techniques have contributed to a better understanding of the pathogenesis of aplastic anemia with respect to the inflammaging, somatic mutations, cytogenetic abnormalities and defective telomerase functions of HSCs. These have been summarized in this review and may be helpful in differentiating aplastic anemia from hypocellular myelodysplastic syndrome. Furthermore, responses to immunosuppressive therapy and outcomes may be determined by molecular pathogenesis of HSCs autoimmune destruction, as well as treatment personalization in the future.