Genome-wide investigation to assess copy number variants in the Italian local chicken population

Background Copy number variants(CNV)hold significant functional and evolutionary importance.Numerous ongoing CNV studies aim to elucidate the etiology of human diseases and gain insights into the population structure of livestock.High-density chips have enabled the detection of CNV with increased resolution,leading to the identification of even small CNV.This study aimed to identify CNV in local Italian chicken breeds and investigate their distribution across the genome.Results Copy number variants were mainly distributed across the first six chromosomes and primarily associated with loss type CNV.The majority of CNV in the investigated breeds were of types 0 and 1,and the minimum length of CNV was significantly larger than that reported in previous studies.Interestingly,a high proportion of the length of chromosome 16 was covered by copy number variation regions(CNVR),with the major histocompatibility complex being the likely cause.Among the genes identified within CNVR,only those present in at least five animals across breeds(n=95)were discussed to reduce the focus on redundant CNV.Some of these genes have been associated to functional traits in chickens.Notably,several CNVR on different chromosomes harbor genes related to muscle development,tissue-specific biological processes,heat stress resistance,and immune response.Quantitative trait loci(QTL)were also analyzed to investigate potential overlapping with the identified CNVR:54 out of the 95 gene-containing regions overlapped with 428 QTL associated to body weight and size,carcass characteristics,egg production,egg components,fat deposition,and feed intake.Conclusions The genomic phenomena reported in this study that can cause changes in the distribution of CNV within the genome over time and the comparison of these differences in CNVR of the local chicken breeds could help in preserving these genetic resources.

Relationship Between Gene-Phenotype and Clinical Manifestations of Chromosomal Copy Number Variations Indicated by Non-Invasive Prenatal Testing

Objective:To analyze the clinical value of non-invasive prenatal testing(NIPT)in detecting chromosomal copy number variations(CNVs)and to explore the relationship between gene expression and clinical manifestations of chromosomal copy number variations.Methods:3551 naturally conceived singleton pregnant women who underwent NIPT were included in this study.The NIPT revealed abnormalities other than sex chromosome abnormalities and trisomy 13,18,and 21.Pregnant women with chromosome copy number variations underwent genetic counseling and prenatal ultrasound examination.Interventional prenatal diagnosis and chromosome microarray analysis(CMA)were performed.The clinical phenotypes and pregnancy outcomes of different prenatal diagnoses were analyzed.Additionally,a follow-up was conducted by telephone to track fetal development after birth,at six months,and one year post-birth.Results:A total of 53 cases among 3551 cases showed chromosomal copy number variation.Interventional prenatal diagnosis was performed in 36 cases:27 cases were negative and 8 were consistent with the NIPT test results.This indicates that NIPT’s positive predictive value(PPV)in CNVs is 22.22%.Conclusion:NIPT has certain clinical significance in screening chromosome copy number variations and is expected to become a routine screening for chromosomal microdeletions and microduplications.However,further interventional prenatal diagnosis is still needed to identify fetal CNVs.

De novel heterozygous copy number deletion on 7q31.31-7q31.32 involving TSPAN12 gene with familial exudative vitreoretinopathy in a Chinese family

AIM:To investigate the genetic and clinical characteristics of patients with a large heterozygous copy number deletion on 7q31.31-7q31.32.METHODS:A family with familial exudative vitreoretinopathy(FEVR)phenotype was included in the study.Whole-exome sequencing(WES)was initially used to locate copy number variations(CNVs)on 7q31.31-31.32,but failed to detect the precise breakpoint.The long-read sequencing,Oxford Nanopore sequencing Technology(ONT)was used to get the accurate breakpoint which is verified by quantitative real-time polymerase chain reaction(QPCR)and Sanger Sequencing.RESULTS:The proband,along with her father and younger brother,were found to have a heterozygous 4.5 Mb CNV deletion located on 7q31.31-31.32,which included the FEVRrelated gene TSPAN12.The specific deletion was confirmed as del(7)(q31.31q31.32)chr7:g.119451239_123956818del.The proband exhibited a phase 2A FEVR phenotype,characterized by a falciform retinal fold,macular dragging,and peripheral neovascularization with leaking of fluorescence.These symptoms led to a significant decrease in visual acuity in both eyes.On the other hand,the affected father and younger brother showed a milder phenotype.CONCLUSION:The heterozygous CNV deletion located on 7q31.31-7q31.32 is associated with the FEVR phenotype.The use of long-read sequencing techniques is essential for accurate molecular diagnosis of genetic disorders.

Copy number variation of B1 controls awn length in wheat

Wheat awns contribute to photosynthesis and grain production.In this study,an F2population and F2:3families from a cross between the awned line 7D12 and the Chinese awnless variety Shiyou 20(SY20)were used to identify loci associated with awn length.Bulked-segregant RNA sequencing and linkage mapping identified a single dominant locus in a 0.3 cM interval on chromosome 5AL.Five genes were in the interval,including the recently cloned awn inhibitor B1.Although a single copy of the B1 gene was detected in 7D12,SY20 carried five copies of the gene.Increased copy number of B1 in SY20enhanced gene expression.Based on sequence variation among the promoter regions of five B1 gene copies in SY20,two dominant markers were developed and found to cosegregate with B1 in a population of 931 wheat accessions.All 77 awnless accessions harbored sequence variations in the B1 promoter regions similar to those of SY20 and thus carried multiple copies of the gene,whereas 15 randomly selected awned wheats carried only one copy.These results suggest that an increase in copy number of the B1 gene is associated with inhibition of awn length.

Benchmark Dose Assessment for Coke Oven Emissions-Induced Mitochondrial DNA Copy Number Damage Effects

Objective The study aimed to estimate the benchmark dose(BMD)of coke oven emissions(COEs)exposure based on mitochondrial damage with the mitochondrial DNA copy number(mtDNAcn)as a biomarker.Methods A total of 782 subjects were recruited,including 238 controls and 544 exposed workers.The mtDNAcn of peripheral leukocytes was detected through the real-time fluorescence-based quantitative polymerase chain reaction.Three BMD approaches were used to calculate the BMD of COEs exposure based on the mitochondrial damage and its 95%confidence lower limit(BMDL).Results The mtDNAcn of the exposure group was lower than that of the control group(0.60±0.29 vs.1.03±0.31;P<0.001).A dose-response relationship was shown between the mtDNAcn damage and COEs.Using the Benchmark Dose Software,the occupational exposure limits(OELs)for COEs exposure in males was 0.00190 mg/m^(3).The OELs for COEs exposure using the BBMD were 0.00170 mg/m^(3)for the total population,0.00158 mg/m^(3)for males,and 0.00174 mg/m^(3)for females.In possible risk obtained from animal studies(PROAST),the OELs of the total population,males,and females were 0.00184,0.00178,and 0.00192 mg/m^(3),respectively.Conclusion Based on our conservative estimate,the BMDL of mitochondrial damage caused by COEs is0.002 mg/m^(3).This value will provide a benchmark for determining possible OELs.

Copy number variation sequencing for diagnosis of cytomegalovirus infection based low-depth whole-genome sequencing technology in fetus:Three cases and literature review

Objective:To summarize the application value of copy number variant sequencing(CNV-seq)in the detection of fetal chromosome and cytomegalovirus load.Methods:The study analyzed the clinical basic data,relevant laboratory tests,treatment process,and outcomes of three patients with positive cytomegalovirus load detected by CNV-seq for fetal chromosomes and cytomegalovirus load,and literature review was done simutaneoubly.Results:In all three cases,the amniotic fluid cytomegalovirus load was less than 105 Copies/ml,and there were no significant neurological abnormalities observed during pregnancy or postpartum follow-up.There is no literature review on the application of CNV-seq technology in the detection of cytomegalovirus infection,only literature reports on genome analysis of CMV-DNA in confirmed patients were available.Conclusion:CNV-seq can be used to detect cytomegalovirus load,which may have a certain degree of predictive value for fetal outcome.CNV-seq can simultaneously detect fetal chromosomes and pathogenic microorganisms,which is of great significance for the prevention and control of birth defects.

Low-depth whole genome sequencing reveals copy number variations associated with higher pathologic grading and more aggressive subtypes of lung non-mucinous adenocarcinoma

Objective:Histology grade,subtypes and TNM stage of lung adenocarcinomas are useful predictors of prognosis and survival.The aim of the study was to investigate the relationship between chromosomal instability,morphological subtypes and the grading system used in lung non-mucinous adenocarcinoma(LNMA).Methods:We developed a whole genome copy number variation(WGCNV)scoring system and applied next generation sequencing to evaluate CNVs present in 91 LNMA tumor samples.Results:Higher histological grades,aggressive subtypes and more advanced TNM staging were associated with an increased WGCNV score,particularly in CNV regions enriched for tumor suppressor genes and oncogenes.In addition,we demonstrate that 24-chromosome CNV profiling can be performed reliably from specific cell types(<100 cells)isolated by sample laser capture microdissection.Conclusions:Our findings suggest that the WGCNV scoring system we developed may have potential value as an adjunct test for predicting the prognosis of patients diagnosed with LNMA.

Scan of the endogenous retrovirus sequences across the swine genome and survey of their copy number variation and sequence diversity among various Chinese and Western pig breeds

In pig-to-human xenotransplantation,the transmission risk of porcine endogenous retroviruses(PERVs)is of great concern.However,the distribution of PERVs in pig genomes,their genetic variation among Eurasian pigs,and their evolutionary history remain unclear.We scanned PERVs in the current pig reference genome(assembly Build 11.1),and identified 36 long complete or near-complete PERVs(lc PERVs)and 23 short incomplete PERVs(si PERVs).Besides three known PERVs(PERV-A,-B,and-C),four novel types(PERV-JX1,-JX2,-JX3,and-JX4)were detected in this study.According to evolutionary analyses,the newly discovered PERVs were more ancient,and PERV-Bs probably experienced a bottleneck~0.5 million years ago(Ma).By analyzing63 high-quality porcine whole-genome resequencing data,we found that the PERV copy numbers in Chinese pigs were lower(32.0±4.0)than in Western pigs(49.1±6.5).Additionally,the PERV sequence diversity was lower in Chinese pigs than in Western pigs.Regarding the lc PERV copy numbers,PERV-A and-JX2 in Western pigs were higher than in Chinese pigs.Notably,Bama Xiang(BMX)pigs had the lowest PERV copy number(27.8±5.1),and a BMX individual had no PERV-C and the lowest PERV copy number(23),suggesting that BMX pigs were more suitable for screening and/or modification as xenograft donors.Furthermore,we identified 451 PERV transposon insertion polymorphisms(TIPs),of which 86 were shared by all 10 Chinese and Western pig breeds.Our findings provide systematic insights into the genomic distribution,variation,evolution,and possible biological function of PERVs.

Prognostic value of MET, cyclin D1 and MET gene copy number in non-small cell lung cancer

The aim of this study was to analyze the correlation of the expression of MET and cyclin D1 and MET gene copy number in non-small cell lung cancer （NSCLC） tissues and patient clinicopathologic characteristics and sur- vival. Sixty-one NSCLC tissue specimens were included in the study. The expression of MET and cyclin D1 was evaluated by immunohistochemistry and MET gene copy number was assessed by quantitative real-time polymer- ase chain reaction （Q-PCR）. Positive expression of MET and cyclin D1 protein and increased MET gene copy number occurred in 59.0%, 59.0% and 18.0% of 61 NSCLC tissues, respectively. MET-positivity correlated with poor differentiation （P = 0.009）. Increased MET gene copy number was significantly associated with lymph node metastasis （P = 0.004） and advanced tumor stage （P = 0.048）, while the expression of cyclin D1 was not associ- ated with any clinicopathologic parameters. There was a significant correlation between the expression of MET and MET gene copy number （P = 0.002）. Additionally, the expression of cyclin D1 had a significant association with the expression of MET as well as MET gene copy number （P = 0.002 and P = 0.017, respectively）. MET- positivity and increased MET gene copy number were significantly associated with poor overall survival （P = 0.003 and P 〈 0.001, respectively） in univariate analysis. Multivariate Cox proportional hazard analysis confirmed that the expression of MET and MET gene copy number were prognostic indicators of NSCLC （P = 0.003 and P = 0.001, respectively）. The overexpression of MET and the increased MET gene copy number might be adverse prognostic factors for NSCLC patients. The activation of the MET/cyclin D1 signaling pathway may contribute to carcino- genesis and the development of NSCLC, and may represent a target for therapy.

EGFR gene copy number as a predictive biomarker for resistance to anti-EGFR monoclonal antibodies in metastatic colorectal cancer treatment:a meta-analysis

Objective：The epidermal growth factor receptor （EGFR） inhibitors monoclonal antibodies （MoAbs） have already shown the therapeutic effectiveness in patients with metastatic colorectal cancer （mCRC）.But many patients resist to the treatment.The aim of this meta-analysis was to assess EGFR gene copy number （GCN） as a candidate predictive biomarker for resistance to anti-EGFR MoAbs in mCRC treatment.Methods：Systematic computerized searches of the PubMed,EMBase and Cochrane Library were performed.The primary endpoint was objective response rate （ORR）.The second endpoints included progression-free survival （PFS）,and overall survival （OS）.The pooled odd ratio （OR） and pooled sensitivity,specificity,and summary receiver operator characteristic （SROC） for ORR were estimated.The pooled hazard ratios （HR） for PFS and OS were also calculated.Results：Fourteen studies with 1,021 patients were included.Increased EGFR GCN was associated with increased ORR （OR=6.905; 95％ CI：4.489-10.620）.It was also found in wild-type KRAS mCRC patients,with the pooled OR of 8.133 （95 ％ CI：4.316-15.326）.GCN has medium value for predicting ORR,with the pooled sensitivity of 0.79 （95％ CI：0.73-0.84）,the pooled specificity of 0.59 （95％ CI：0.55-0.62）.In wildtype KRAS mCRC patients,the sensitivity and the specificity were 0.80 （95％ CI：0.70-0.87） and 0.60 （95％CI：0.53-0.66）,respectively.Increased EGFR GCN was associated with increased PFS （HR=0.557; 95％ CI：0.382-0.732） and OS （HR=0.579; 95％ CI：0.422-0.737）.Conclusions：This meta-analysis suggests that EGFR GCN represents a predictive biomarker for tumor response in mCRC patients treated with MoAbs regardless of KRAS mutation.mCRC patients with increased EGFR GCN are more likely to have a better response,PFS,and OS when treated with cetuximab or panitumumab.

AB015.The relationship between copy number variations and high myopia in Chinese:a case-control study

As a complex disease,myopia is the most common eye disease worldwide.Many myopia susceptibility genes or variants have been successfully identified in the past years by genome-wide genetic association studies(GWAS),which focus mainly on the single-nucleotide polymorphisms.Little attention has been paid to examine the role of copy number variations(CNVs)in refractive error and myopia.This study adopted a systematic strategy to investigate the role of CNVs in high myopia.In the discovery phase,a pilot GWAS suggests putative CNVs for follow-up.Multiplex ligation-dependent probe amplification was then used to quantify the copy number of 89 CNV segments in 737 case-control samples in the second phase and then 24 top-ranking CNVs in a second group of 1,029 case-control samples in the final validation phase.This validation phase identified 22 significant CNVs.Further work is needed to examine the role of these few CNVs in myopia development.

Establishment of Real-Time Quantitative PCR Method for the Determination of Transposon Copy Number in Cronobacter sakazakii

[Objective] This study aimed to establish a Real-Time quantitative PCR method for the determination of transposon copy number in C. sakazakii. [ Method ] With single-copy housekeeping gene atpD as the reference gene, recombinant plasmid containing both single-copy housekeeping gene atpD and EZ-TN5 transposon was constructed; based on the established standard curves for real-time quantitative detection of atpD gene and EZ-TN5 transposon, copy number of atpD gene and EZ-TN5 transpason in three C. sakazakii mutants was detected and the ratio was calculated. [ Result] Correlation coefficients of the standard curves for real-time quantitative detection of atpD gene and EZ-TN5 transposon were 0. 999 and 0.998, respectively ; the ratios of copy number of atpD gene and EZ-TN5 transposon in three C. sakazakii mutants were 0.98, 1.17 and 0.91, respectively, which indicates that EZ-TN5 transpeson in C. sakakii mutants is a single-copy. [ Conclusion] Real-time quantitative PCR method established in this study had high availability and could replace the Southern blot method to detect the copy num- ber of EZ-TN5 transposon in different bacteria.

SMARCC1 copy number variation is related to metastatic colon cancer:an investigation based on TCGA data

Objective There are no well-defined genetic indicators for distant metastatic illness in patients with colon cancer(CC).The discovery of genetic changes linked to metastatic CC might aid in the development of systemic and local therapeutic approaches.Using The Cancer Genome Atlas(TCGA),we examined the relationship between copy number variation(CNV)of SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily C member 1(SMARCC1)and distant metastatic illness in patients with CC.Methods Genetic sequencing data of all relevant CC patients and clinical features were collected from TCGA using R.There were 506 CC patients with CNV and clinical outcome data.The CNV of SMARCC1 was examined for its correlation with distant metastatic disease using the TCGA CC dataset(M1 vs.M0).After adjusting for age,sex,T stage,N stage,adjuvant chemotherapy,microsatellite instability(MSI),and surgical margin status,univariate and multivariate logistic regression analyses were performed.Results SMARCC1 CNV was linked to distant metastatic disease(P=0.012 and 0.008 in univariate and multivariate analysis,respectively);positive lymph nodes and margin status were also associated with distal metastases(all P<0.01).MSI,T stage,N stage,adjuvant treatment,sex,race,and MSI were not associated with metastases(all P>0.05).Conclusion SMARCC1 CNV is associated with distant metastatic disease in patients with CC.In individuals with CC,such genetic profiles might be utilized therapeutically to support optimal systemic treatment options against local treatments for CC,such as radiation therapy,pending additional confirmation.

Integrated Analysis of the Gene Expression Profiling and Copy Number Aberration of the Ovarian Cancer

Objective: DNA copy number alterations and difference expression are frequently observed in ovarian cancer. The purpose of this way was to pinpoint gene expression change that was associated with alterations in DNA copy number and could therefore enlighten some potential oncogenes and stability genes with functional roles in cancers, and investigated the bioinformatics significance for those correlated genes. Method: We obtained the DNA copy number and mRNA expression data from the Cancer Genomic Atlas and identified the most statistically significant copy number alteration regions using the GISTIC. Then identified the significance genes between the tumor samples within the copy number alteration regions and analyzed the correlation using a binary matrix. The selected genes were subjected to bioinformatics analysis using GSEA tool. Results: GISTIC analysis results showed there were 45 significance copy number amplification regions in the ovarian cancer, SAM and Fisher’s exact test found there have 40 genes can affect the expression level, which located in the amplification regions. That means we obtained 40 genes which have a correlation between copy number amplification and drastic up- and down-expression, which p-value < 0.05 (Fisher’s exact test) and an FDR < 0.05. GSEA enrichment analysis found these genes were overlapped with the several published studies which were focused on the gene study of tumorigenesis. Conclusion: The use of statistics and bioinformatics to analyze the microarray data can found an interaction network involved. The combination of the copy number data and expression has provided a short list of candidate genes that are consistent with tumor driving roles. These would offer new ideas for early diagnosis and treat target of ovarian cancer.

Genetic Copy Number Variations in Colon Mucosa Indicating Risk for Colorectal Cancer

Background: Sporadic colorectal tumors probably carry genetic alterations that may be related to familiar clusters according to risk loci visualized by SNP arrays on normal tissues. The aim of the present study was therefore to search for DNA regions (copy number variations, CNVs) as biomarkers associated to genetic susceptibility for early risk predictions of colorectal cancer. Such sequence alterations could provide additional information on phenotypic grouping of patients. Material and Methods: High resolution 105K oligonucleotide microarrays were used in search for CNV loci in DNA from tumor-free colon mucosa at primary operations for colon cancer in 60 unselected patients in comparison to DNA in buffy coat cells from 44 confirmed tumor-free and healthy blood donors. Array-detected CNVs were confirmed by Multiplex ligation-dependent probe amplification (MLPA). Results: A total number of 205 potential CNVs were present in DNA from colon mucosa. 184 (90%) of the 205 potential CNVs had been identified earlier in mucosa DNA from healthy individuals as reported to the Database of Genomic Variants. Remaining 21 (10%) CNVs were potentially novel sites. Two CNVs (3q23 and 10q21.1) were significantly related to colon cancer, but not confirmed in buffy coat DNA from the cancer patients. Conclusion: Our study reveals two CNVs that indicate increased risk for colon cancer;These DNA alterations may have? been acquired by colon stem cells with subsequent appearance among epithelial mucosa cells. Impact: Certain mucosa CNV alterations may indicate individual susceptibility for malignant transformation in relationship to intestinal toxins and bacterial growth.

Exploring correlations among copy number variants

There have been a great many recent studies investigating the extent of Copy Number Variation in the genomes of various species such as human, cattle, dogs and many others. The results from these studies indicate that the extent of the Copy Number Variation in the genome is considerable, and that in humans and in cattle, frequencies of different Copy Number Variants may differ in different breeds/ethnicities. This is not entirely unexpected as allele frequencies of certain loci vary with different breeds/ ethnicities/species and many known Copy Number Variants behave similarly to ordinary markers as regards Mendelian segregation. It is also well known in many instances, species/breeds/ethnicities show variation not only in marker allele frequencies, but also in the extent of Linkage Disequilibrium between markers. Thus it is worth investigating the extent of association between Copy Number Variants in different populations. In this paper we will investigate the extent of correlations between selected Copy Number Variants in different human populations and show that statistically significant correlations exist and are strongly population dependent.

Next‑Generation Sequencing‑Based Copy Number Variation Analysis in Chinese Patients with Primary Ciliary Dyskinesia Revealed Novel DNAH5 Copy Number Variations

Primary ciliary dyskinesia(PCD)is a rare disorder characterized by extensive genetic heterogeneity.However,in the genetic pathogenesis of PCD,copy number variation(CNV)has not received sufcient attention and has rarely been reported,especially in China.Next-generation sequencing(NGS)followed by targeted CNV analysis was used in patients highly suspected to have PCD with negative results in routine whole-exome sequencing(WES)analysis.Quantitative real-time polymerase chain reaction(qPCR)and Sanger sequencing were used to confrm these CNVs.To further characterize the ciliary phenotypes,high-speed video microscopy analysis(HSVA),transmission electron microscopy(TEM),and immunofuorescence(IF)analysis were used.Patient 1(F1:II-1),a 0.6-year-old girl,came from a nonconsanguineous family-I.She presented with situs inversus totalis,neonatal respiratory distress,and sinusitis.The nasal nitric oxide level was markedly reduced.The respiratory cilia beat with reduced amplitude.TEM revealed shortened outer dynein arms(ODA)of cilia.chr5:13717907-13722661del spanning exons 71–72 was identifed by NGS-based CNV analysis.Patient 2(F2:IV-4),a 37-year-old man,and his eldest brother Patient 3(F2:IV-2)came from a consanguineous family-II.Both had sinusitis,bronchiectasis and situs inversus totalis.The respiratory cilia of Patient 2 and Patient 3 were found to be uniformly immotile,with ODA defects.Two novel homozygous deletions chr5:13720087_13733030delinsGTTTTC and chr5:13649539_13707643del,spanning exons 69–71 and exons 77–79 were identifed by NGS-based CNV analysis.Abnormalities in DNA copy number were confrmed by qPCR amplifcation.IF showed that the respiratory cilia of Patient 1 and Patient 2 were defcient in dynein axonemal heavy chain 5(DNAH5)protein expression.This report identifed three novel DNAH5 disease-associated variants by WES-based CNV analysis.Our study expands the genetic spectrum of PCD with DNAH5 in the Chinese population.

The influence of the copy number of invader on the fate of bacterial host cells in the antiviral defense by CRISPR-Cas10 DNases

Type Ⅲ CRISPR-Cas10 systems employ multiple immune activities to defend their hosts against invasion from mobile genetic elements(MGEs),including DNase and cyclic oligoadenylates(cOA)synthesis both of which are hosted by the type-specific protein Cas10.Extensive investigations conducted for the activation of Cas accessory proteins by cOAs have revealed their functions in the type Ⅲ immunity,but the function of the Cas10 DNase in the same process remains elusive.Here,Lactobacillus delbrueckii subsp.Bulgaricus type Ⅲ-A(Ld)Csm system,a type Ⅲ CRISPR system that solely relies on its Cas10 DNase for providing immunity,was employed as a model to investigate the DNase function.Interference assay was conducted in Escherichia coli using two plasmids:pCas carrying the LdCsm system and pTarget producing target RNAs.The former functioned as a de facto“CRISPR host element”while the latter,mimicking an invading MGE.We found that,upon induction of immune responses,the fate of each genetic element was determined by their copy numbers:plasmid of a low copy number was selectively eliminated from the E.coli cells regardless whether it represents a de facto CRISPR host or an invader.Together,we reveal,for the first time,that the immune mechanisms of Cas10 DNases are of two folds:the DNase activity is capable of removing low-copy invaders from infected cells,but it also leads to abortive infection when the invader copy number is high.

Number matters:control of mammalian mitochondrial DNA copy number

Regulation of mitochondrial biogenesis is essential for proper cellular functioning. Mitochondrial DNA （mtDNA） depletion and the resulting mitochondrial malfunction have been implicated in cancer, neurodegeneration, diabetes, aging, and many other human diseases. Although it is known that the dynamics of the mammalian mitochondrial genome are not linked with that of the nuclear genome, very little is known about the mechanism of mtDNA propagation. Nevertheless, our understanding of the mode of mtDNA replication has ad- vanced in recent years, though not without some controversies. This review summarizes our current knowledge of mtDNA copy number control in mammalian cells, while focusing on both mtDNA replication and turnover. Although mtDNA copy number is seemingly in excess, we reason that mtDNA copy number control is an important aspect of mitochondrial genetics and biogenesis and is essential for normal cellular function.

Clinical significance of germline copy number variation in susceptibility of human diseases

Germline copy number variation （CNV） is considered to be an important form of human genetic poly- morphisms. Previous studies have identified amounts of CNVs in human genome by advanced technologies, such as comparative genomic hybridization, single nucleotide genotyping, and high-throughput sequencing. CNV is speculated to be derived from multiple mechanisms, such as nonallelic homologous recombination （NAHR） and nonhomologous end-joining （NHEJ）. CNVs cover a much larger genome scale than single nucleotide polymorphisms （SNPs）, and may alter gene expression levels by means of gene dosage, gene fusion, gene disruption, and long-range regulation effects, thus affecting individual phenotypes and playing crucial roles in human pathogenesis. The number of studies linking CNVs with common complex diseases has increased dramatically in recent years. Here, we provide a comprehensive review of the current understanding ofgermline CNVs, and summarize the association of germline CNVs with the susceptibility to a wide variety of human diseases that were identified in recent years. We also propose potential issues that should be addressed in future studies.