Germline pathogenic variants among high hereditary risk patients with breast and ovarian cancer and unaffected subjects in Lebanese Arab women

BACKGROUND The prevalence of germline pathogenic variants in high hereditary risk breast and/or ovarian cancer patients and unaffected subjects referred for testing is an unmet need in low and middle-income countries.AIM To determine the prevalence of germline pathogenic variants in high hereditary risk patients with breast and/or ovarian cancer and unaffected individuals.METHODS We retrospectively reviewed records of patients and unaffected subjects referred for germline pathogenic variant testing due to high hereditary risk between 2010-2020.Data was collected and analyzed on Excel sheet.RESULTS In total,358 individuals were included,including 257 patients and 101 unaffected individuals with relatives with breast or ovarian cancer.The prevalence of breast cancer susceptibility gene(BRCA)1/2 pathogenic variants was 8.63%(19/220)in patients with breast cancer,and 15.1%(5/33)in those with ovarian cancer.Among the 25 of 220 patients with breast cancer tested by next-generation sequencing,3 patients had pathogenic variants other than BRCA1/2.The highest risk was observed in those aged 40 years with breast cancer and a positive family history,where the BRCA1/2 prevalence was 20.1%(9/43).Among the unaffected subjects,31.1%(14/45)had the same BRCA1/2 pathogenic variants in their corresponding relatives.Among the subjects referred because of a positive family history of cancer without known hereditary factors,5.35%(3/56)had pathogenic variants of BRCA1 and BRCA2.The c.131G>T nucleotide change was noted in one patient and two unrelated unaffected subjects with a BRCA1 pathogenic variant.CONCLUSION This study showed a 8.63%prevalence of pathogenic variants in patients with breast cancer and a 15.1%prevalence in patients with ovarian cancer.Among the relatives of patients with BRCA1/2 pathogenic variants,31%tested positive for the same variant,while 5.3%of subjects who tested positive due to a family history of breast cancer had a BRCA pathogenic variant.

Germline MLH1 and MSH2 mutational spectrum including frequent large genomic aberrations in Hungarian hereditary non-polyposis colorectal cancer families:Implications for genetic testing

AIM: To analyze the prevalence of germline MLH1 and MSH2 gene mutations and evaluate the clinical characteristics of Hungarian hereditary non-polyposis colorectal cancer (HNPCC) families. METHODS: Thirty-six kindreds were tested for mutations using conformation sensitive gel electrophoreses, direct sequencing and also screening for genomic rearrangements applying multiplex ligation-dependent probe amplifi cation (MLPA). RESULTS: Eighteen germline mutations (50%) were identifi ed, 9 in MLH1 and 9 in MSH2. Sixteen of these sequence alterations were considered pathogenic, the remaining two were non-conservative missense alterations occurring at highly conserved functional motifs. The majority of the defi nite pathogenic mutations (81%, 13/16) were found in families fulfilling the stringent Amsterdam Ⅰ/Ⅱ criteria, including three rearrangements revealed by MLPA (two in MSH2 and one in MLH1). However, in three out of sixteen HNPCC-suspected families (19%), a disease-causing alteration could be revealed. Furthermore, nine mutations described here are novel, and none of the sequence changes were found in more than one family.CONCLUSION: Our study describes for the f irst time the prevalence and spectrum of germline mismatch repair gene mutations in Hungarian HNPCC and suspected-HNPCC families. The results presented here suggest that clinical selection criteria should be relaxed and detection of genomic rearrangements should be included in genetic screening in this population.

Dmrt1 regulates the immune response by repressing the TLR4 signaling pathway in goat male germline stem cells

Double sex and mab-3-related transcription factor 1(Dmrt1),which is expressed in goat male germline stem cells(mGSCs)and Sertoli cells,is one of the most conserved transcription factors involved in sex determination.In this study,we highlighted the role of Dmrt1 in balancing the innate immune response in goat mGSCs.Dmrt1 recruited promyelocytic leukemia zinc finger(Plzf),also known as zinc finger and BTB domain-containing protein 16(Zbtb16),to repress the Toll-like receptor 4(TLR4)-dependent inflammatory signaling pathway and nuclear factor(NF)-κB.Knockdown of Dmrt1 in seminiferous tubules resulted in widespread degeneration of germ and somatic cells,while the expression of proinflammatory factors were significantly enhanced.We also demonstrated that Dmrt1 stimulated proliferation of mGSCs,but repressed apoptosis caused by the immune response.Thus,Dmrt1 is sufficient to reduce inflammation in the testes,thereby establishing the stability of spermatogenesis and the testicular microenvironment.

Prevalence and clinical significance of pathogenic germline BRCA1/2 mutations in Chinese non-small cell lung cancer patients

Objective: Germline alterations in the breast cancer susceptibility genes type 1 and 2, BRCA1 and BRCA2, predispose individuals to hereditary cancers, including breast, ovarian, prostate, pancreatic, and stomach cancers.Accumulating evidence suggests inherited genetic susceptibility to lung cancer.The present study aimed to survey the prevalence of pathogenic germline BRCA mutations(gBRCAm) and explore the potential association between gBRCAm and disease onset in Chinese advanced non-small cell lung cancer(NSCLC) patients.Methods: A total of 6,220 NSCLC patients were screened using capture-based ultra-deep targeted sequencing to identify patients harboring germline BRCA1/2 mutations.Results: Out of the 6,220 patients screened, 1.03%(64/6,220) of the patients harbored the pathogenic gB RCAm, with BRCA2 mutations being the most predominant mutations(49/64, 76.5%).Patients who developed NSCLC before 50 years of age were more likely to carry gBRCAm(P = 0.036).Among the patients harboring classic lung cancer driver mutations, those with concurrent gBRCAm were significantly younger than those harboring the wild-type gBRCA(P = 0.029).By contrast, the age of patients with or without concurrent gBRCAm was comparable to those of patients without the driver mutations(P = 0.972).In addition, we identified EGFR-mutant patients with concurrent gBRCAm who showed comparable progression-free survival but significantly longer overall survival(P = 0.002) compared to EGFR-mutant patients with wild-type germline BRCA.Conclusions: Overall, our study is the largest survey of the prevalence of pathogenic gBRCAm in advanced Chinese NSCLC patients.Results suggested a lack of association between germline BRCA status and treatment outcome of EGFR-TKI.In addition,results showed a positive correlation between pathogenic gB RCAm and an early onset of NSCLC.

Germline promoter hypermethylation of tumor suppressor genes in gastric cancer

AIM: To explore germline hypermethylation of the tumor suppressor genes MLH1, CDH1 and P16INK4a in suspected cases of hereditary gastric cancer (GC). METHODS: A group of 140 Chinese GC patients in whom the primary cancer had developed before the age of 60 or who had a familial history of cancer were screened for germline hypermethylation of the MLH1, CDH1 and P16INK4a tumor suppressor genes. GenomicDNA was extracted from peripheral blood leukocytes and modified by sodium bisulfite. The treated DNA was then subjected to bisulfi te DNA sequencing for a specif ic region of the MLH1 promoter. The methylation status of CDH1 or P16INK4a was assayed using methylation-specif ic PCR. Clonal bisulf ite allelic sequencing in positive samples was performed to obtain a comprehensive analysis of the CpG island methylation status of these promoter regions. RESULTS: Methylation of the MLH1 gene promoter was detected in the peripheral blood DNA of only 1/140 (0.7%) of the GC patient group. However, this methylation pattern was mosaic rather than the allelic pattern which has previously been reported for MLH1 in hereditary non-polyposis colorectal cancer (HNPCC) patients. We found that 10% of the MLH1 alleles in the peripheral blood DNA of this patient were methylated, consistent with 20% of cells having one methylated allele. No germline promoter methylation of the CDH1 or P16INK4a genes was detected. CONCLUSION: Mosaic germline epimutation of the MLH1 gene is present in suspected hereditary GC patients in China but at a very low level. Germline epimutation of the CDH1 or P16INK4a gene is not a frequent event.

MLH1 promoter germline-methylation in selected probands of Chinese hereditary non-polyposis colorectal cancer families

AIM： To detect the MLH1 gene promoter germline- methylation in probands of Chinese hereditary non- polyposis colorectal cancer （HNPCC）, and to evaluate the role of methylation in MLH1 gene promoter and molecular genetics in screening for HNPCC.METHODS： The promoter germline methylation of MLH1 gene was detected by methylation-specific PCR （MSP） in 18 probands from unrelated HNPCC families with high microsatellite-instability （MSI-H） phenotype but without germline mutations in MSH2, MLH1 and MSH6 genes. At the same time, 6 kindreds were col- lected with microsatellite-stability （MSS） phenotype but without germline mutations in MSH2, MIH1 and MSH6 genes as controls. The results of MSP were confirmed by clone sequencing. To ensure the reliability of the results, family H65 with nonsense germline mutation at c.2228C 〉 A in MSH2 gene was used as the negative control and the cell line sw48 was used as the known positive control along with water as the blank control. Immunochemical staining of MIH1 protein was performed with Envision two-step method in those patients with aberrant methylation to judge whether the status of MLH1 gene methylation affects the expression of MLH1 protein.RESULTS： Five probands with MIH1 gene promoter methylation were detected in 18 Chinese HNPCC families with MSI-H phenotype but without germline mutations in MSH2, MLH1 and MSH6 genes. Two of the five probands from families H10 and H29 displayed exhaustive-methylation, fulfilling the Japanese criteria （JC） and the Amsterdam criteria （AC）, respectively. The other 3 probands presented part-methylation fulfilling the AC. Of the 13 probands with unmethylation phenotype, 8 fulfilled the JC and the Bethesda guidelines （BG）, 5 fulfilled the AC. The rate of aberrant methylation in MLH1 gene in the AC group （22.2%, 4/18） was higher than that in the JC/BG groups （5.6%, 1/18） in all HNPCC families with MSI-H phenotype but without germline mutations in PISH2, PIIH1 and MSH6 genes. However, no proband with methylation in MLH1 gene was found in the families with MSS phenotype and without germline mutations in MSH2, MLH1 and MSH6 genes. No expression of MLH1 protein was found in tumor tissues from two patients with exhaustive-methylation phenotype, whereas positive expression of MLH1 protein was observed in tumor tissues from patients with partial methylation phenotype （excluding family H42 without tumor tissue）, indicating that exhaustive-methylation of MLH1 gene can cause defective expression of MLH1 protein.CONCLUSION： Methylation phenotype of MLH1 gene is correlated with microsatellite phenotype of MMR genes, especially with MSI-H. Exhaustive-methylation of MLH1 gene can silence the expression of MLH1 protein. MLH1 promoter methylation analysis is a promising tool for molecular genetics screening for HNPCC.

Detection of germline mutations of hMLH1 and hMSH2 based on cDNA sequencing in China

AIM： TO detect the germline mutations Of hMLH1 and hMSH2 based on mRNA sequencing to identify hereditary non polyposis oolorectal cancer （HNPCC） families. METHODS： Total RNA was extracted from peripberal blood of 14 members from 12 different families fulfilling Amsterdam criteria II. mRNA of hMLH1 and hMSH2 was reversed with special primers and heat-resistant reverse tmnscriptase, cDNA was amplified with expand long template PCR and cDNA sequendng analysis was followed. RESULT： Seven germline mutations were found in 6 families （6/12, 50%）, in 4 hMLH1 and 3 hMSH2 mutations （4/12, 33.3%）; （3/12, 25%）. The mutation types involved 4 missense, 1 silent and 1 frame shift mutations as well as 1 mutation in the non-coding area. Four out of the seven mutations have not been reported previously. The 4 hMLH1 mutations were distributed in exons 8, 12, 16, and 19. The 3 hMSH2 mutations were distributed in exons 1 and 2. Six out of the 7 mutations were pathological, which were dislTibuted in 5 HNPCC families. CONCLUSION： Germline mutations of hMLH1 and hMSH2 can be found based on cDNA sequencing so as to identify HNPCC family, which is highly sensitive and has the advantages of cost and time saving.

Germline mutation analysis of MLH1 and MSH2 in Malaysian Lynch syndrome patients

AIM: To investigate the protein expression profi le of mismatch repair (MMR) genes in suspected cases of Lynch syndrome and to characterize the associated germline mutations. METHODS: Immunohistochemical analysis of tumor samples was performed to determine the protein expression profile of MMR protein. Germline mutation screening was carried out on peripheral blood samples. The entire exon regions of MLH1 and MSH2 geneswere amplifi ed by polymerase chain reaction, screened by denaturing high performance liquid chromatography (dHPLC) and analyzed by DNA sequencing to characterize the germline mutations. RESULTS: Three out of 34 tissue samples (8.8%) and four out of 34 tissue samples (11.8%) showed loss of nuclear staining by immunohistochemistry, indicating the absence of MLH1 and MSH2 protein expression in carcinoma cells, respectively. dHPLC analysis followed by DNA sequencing showed these samples to have germline mutations of MSH2 gene. However, no deleterious mutations were identifi ed in any of the 19 exons or coding regions of MLH1 gene, but we were able to identify MLH1 promoter polymorphism, -93G > A (rs1800734), in 21 out of 34 patients (61.8%). We identified one novel mutation, transversion mutation c.2005G > C, which resulted in a missense mutation (Gly669Arg), a transversion mutation in exon 1, c.142G > T, which resulted in a nonsense mutation (Glu48Stop) and splice-site mutation, c.2006-6T > C, which was adjacent to exon 13 of MSH2 gene. CONCLUSION: Germline mutations were identified in four Malaysian Lynch syndrome patients. Immunohistochemical analysis of tumor tissue proved to be a good pre-screening test before proceeding to germline mutation analysis of DNA MMR genes.

Novel CDH1 germline mutations identified in Chinese gastric cancer patients

AIM:To give a comprehensive report of E-cadheringene (CDH1) variations in a population at a high risk for gastric cancer (GC).METHODS:The samples consisted of 178 men and 58 women with a mean age of 62.3 ± 9.4 years and an age range of 30-84 years.A total of 240 cancerfree controls were recruited (mean age of 61.8 ± 10.1 years,age range of 26-82 years).Samples were screened for CDH1 germline mutations by high-resolution melting analysis or directly sequencing.Luciferase reporter assay,RNA splicing assay and bioinformatic analysis were used to evaluate the effect of mutations.RESULTS:Four novel CDH1 sequence alterations were identified in GC patients including a G>T transition 49 bp before the start codon;a three-nucleotide deletion,c.44_46del TGC;one missense mutation,c.604G>A (V202I);and one variation in the intron,c.1320+7A>G.In addition,polymorphism frequencies were observed for CDH1-164delT,-161C>A,-73A>C,c.48+6C>T,c.48+62_48+63delinsCGTGCCCCAGCCC,c.894C>T (A298A),c.1224G>A (A408A),c.1888C>G (L630V),c.2076T>C (A692A),and c.2253C>T (N751N) which is similar to the data reported in http://www.ncbi.nlm.nih.gov/projects/SNP/.RNA splicing analysis suggested that the c.1320+7A>G and c.1224G>A variations did not affect exon splicing ability.Luciferase reporter assay demonstrated that the c.-49T variation might be helpful for E-cadherin transcription,though the increase in transcription activity is limited (only 33%).SIFT score and PolyPhen analysis both demonstrated that the L630V missense mutation probably damages protein function,while the V202I variant does not.CONCLUSION:This study reveals novel mutations in sporadic GC patients which had been poorly investigated for susceptibility genes.

Imatinib response of gastrointestinal stromal tumor patients with germline mutation on KIT exon 13:A family report

Familial gastrointestinal stromal tumor(GIST) is a rare autosomal dominant disorder associated with mutations in the KIT gene in the majority of cases. Although, exon 11 appears to be the hot spot region for approximately 95% of germline mutations, pathogenic variations have also been identified in exon 8, 13 and 17. Exon 13 germline mutations are extremely rare amongst familial GISTs and seven families with a germline mutation have been reported to date. Moreover, the role of imatinib mesylate in this rare familiar settings is not completely known so far. We describe here clinical, imaging, pathological and genetic findings of a family with four affected members; grandmother, his son and two grand-sons having a germline gain-of-function mutation of KIT in exon 13 and discuss the imatinib mesylate treatment surveillance outcomes towards disease management.

A germline variant N375S in MET and gastric cancer susceptibility in a Chinese population

MET tyrosine kinase and its ligand,hepatocyte growth factor（HGF）,play a pivotal role in the activties of tumor cells.A germline missense variant in exon 2 of the MET gene,N375S（rs33917957 A〉G）,may alter the binding affinity of MET for HGF and thus modify the risk of tumorigenesis.In this study,we performed a case-control study to assess the association between N375S and gastric cancer risk in 1,681 gastric cancer cases and 1,858 cancer-free controls.Logistic regression analysis was applied to estimate crude and adjusted odds ratios（ORs） and 95% confidence intervals（CIs） for the associations between genotypes and gastric cancer risk.We found that MET N375S variant genotypes（NS/SS） were associated with a significantly decreased risk of gastric cancer（OR = 0.78,95% CI = 0.63-0.96,P = 0.021） compared with the wildtype homozygote（NN）.The finding indicates that this germline variant in MET may decrease gastric cancer susceptibility in Han Chinese.

Identification of a novel germline missense mutation of the androgen receptor in African American men with familial prostate cancer

Race, family history and age are the unequivocally accepted risk factors for prostate cancer （PCa）. Androgen receptor （AR）-dependent signaling is an important element in prostate carcinogenesis and its progression to metastatic disease. We examined the possibility of genomic changes in the AR in association with familial PCa in African Americans who have a higher incidence and mortality rate and a clinically more aggressive disease presentation than Caucasians. Genomic DNAs of 60 patients from 30 high-risk African American and Caucasian families participating in the Louisiana State University Health Sciences Center genetic linkage study of PCa were studied. Exon-specific polymerase-chain reaction, bi-directional automated sequencing and restriction enzyme genotyping were used to analyze for mutations in the coding region of the AR gene. We identified a germline AR （A1675T） （T559S） substitution mutation in the DNA-binding domain in three PCa-affected members of an African- American family with a history of early-onset disease. The present study describes the first AR germline mutation in an African-American family with a history of familial PCa. The AR （T559S） mutation may contribute to the disease by altering AR DNA-binding affinity and/or its response to androgens, non-androgenic steroids or anti-androgens. Additional studies will be required to define the frequency and contribution of the AR （A 1675T） allele to early-onset and/or familial PCa in African Americans.

Current progress and questions in germline genetics of prostate cancer

Dramatic progress has been made in the area of germline genetics of prostate cancer(PCa)in the past decade.Both common and rare genetic variants with effects on risk ranging from barely detectable to outright practice-changing have been identified.For men with high risk PCa,the application of genetic testing for inherited pathogenic mutations is becoming standard of care.A major question exists about which additional populations of men to test,as men at all risk levels can potentially benefit by knowing their unique genetic profile of germline susceptibility variants.This article will provide a brief overview of some current issues in understanding inherited susceptibility for PCa.

Comprehensive characterization of CRC with germline mutations reveals a distinct somatic mutational landscape and elevated cancer risk in the Chinese population

Objective:Hereditary colorectal cancer(CRC)accounts for approximately 5%–10%of all CRC cases.The full profile of CRC-related germline mutations and the corresponding somatic mutational profile have not been fully determined in the Chinese population.Methods:We performed the first population study investigating the germline mutation status in more than 1,000(n=1,923)Chinese patients with CRC and examined their relationship with the somatic mutational landscape.Germline alterations were examined with a 58-gene next-generation sequencing panel,and somatic alterations were examined with a 605-gene panel.Results:A total of 92 pathogenic(P)mutations were identified in 85 patients,and 81 likely pathogenic(LP)germline mutations were identified in 62 patients,accounting for 7.6%(147/1,923)of all patients.MSH2 and APC was the most mutated gene in the Lynch syndrome and non-Lynch syndrome groups,respectively.Patients with P/LP mutations had a significantly higher ratio of microsatellite instability,highly deficient mismatch repair,family history of CRC,and lower age.The somatic mutational landscape revealed a significantly higher mutational frequency in the P group and a trend toward higher copy number variations in the non-P group.The Lynch syndrome group had a significantly higher mutational frequency and tumor mutational burden than the nonLynch syndrome group.Clustering analysis revealed that the Notch signaling pathway was uniquely clustered in the Lynch syndrome group,and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group.Population risk analysis indicated that the overall odds ratio was 11.13(95%CI:8.289–15.44)for the P group and 20.68(95%CI:12.89–33.18)for the LP group.Conclusions:Distinct features were revealed in Chinese patients with CRC with germline mutations.The Notch signaling pathway was uniquely clustered in the Lynch syndrome group,and the MAPK and cAMP signaling pathways were uniquely clustered in the non-Lynch syndrome group.Patients with P/LP germline mutations exhibited higher CRC risk.

Establishment and characterization of immortalized bovine male germline stem cell line

Male germline stem cells （mGSCs） are unique adult germ cells with self-renewal potential and spermatogenesis function in the testis. However, further studies are needed to establish a long-term cultural system of mGSCs in vitro, especially for large animals such as bovine mGSCs. In this study, we first established a stable immortalized bovine male germline stem cell line by transducing Simian virus 40 （SV40） large T antigen. The proliferation of these cells was improved significantly. These cells could express spermatogonial stem cell （SSC）-specific markers, such as PLZF, PGP9.5, VASA, LIN28A, and CD49F, both in the mRNA and protein levels. Additionally, these cells could be differentiated into three germ layer cells to enter meiosis, form colonies, and proliferate in the seminiferous tubules of busulfan-induced infertile mice. The immortalized bovine mGSCs maintain the criteria of mGSCs.

Harnessing male germline epigenomics for the genetic improvement in cattle

Sperm is essential for successful artificial insemination in dairy cattle,and its quality can be influenced by both epi-genetic modification and epigenetic inheritance.The bovine germline differentiation is characterized by epigenetic reprogramming,while intergenerational and transgenerational epigenetic inheritance can influence the offspring’s development through the transmission of epigenetic features to the offspring via the germline.Therefore,the selec-tion of bulls with superior sperm quality for the production and fertility traits requires a better understanding of the epigenetic mechanism and more accurate identifications of epigenetic biomarkers.We have comprehensively reviewed the current progress in the studies of bovine sperm epigenome in terms of both resources and biological discovery in order to provide perspectives on how to harness this valuable information for genetic improvement in the cattle breeding industry.

Two novel germline mutations of MLH1 and investigation of their pathobiology in hereditary non-polyposis colorectal cancer families in China

AIM： To detect germline mutations of MLH1, and investigate microsatellite instability and expression of MLH1 in tumor tissues of hereditary non-polyposis colorectal cancer （HNPCC） with two novel germline mutations, and further investigate the pathobiology of the two novel mutations of MLH1. METHODS： RNA was extracted from the peripheral blood of 12 patients from 12 different families that fulfilled the Amsterdam 11 Criteria for HNPCC. Germline mutations of MLH1 were determined by RT-PCR, followed by cDNA sequencing analysis. PCR-GeneScan analysis was used to investigate microsatellite instability with a panel of five microsatellite markers （BAT26, BAT25, D5S346, D2S123 and mfd15）, along with immunohistochemical staining to detect the expression of MLH1 protein in two patients＇ tumor tissues with novel mutations. RESULTS： Three germline mutations were found in four patients, one of the mutations has previously been reported, but the other two, CGC→TGC at codon 217 of exon 8 and CCG→CTG at codon 581 of exon 16, have not been reported. The two patients＇ tumor tissues with novel mutations had high-frequency microsatellite instability that showed more than two unstable loci, and both tumors lost their MLH1 protein expression. CONCLUSION： The two novel germline mutations of MLH1 in HNPCC families i.e. CGC→TGC at codon 217 of exon 8 and CCG→CTG at codon 581 of exon 16, are very likely to have pathological significance.

Germline competence of mouse ES and iPS cell lines: Chimera technologies and genetic background

In mice,gene targeting by homologous recombination continues to play an essential role in the understanding of functional genomics.This strategy allows precise location of the site of transgene integration and is most commonly used to ablate gene expression("knock-out"),or to introduce mutant or modified alleles at the locus of interest("knock-in").The efficacy of producing live,transgenic mice challenges our understanding of this complex process,and of the factors which influence germline competence of embryonic stem cell lines.Increasingly,evidence indicates that culture conditions and in vitro manipulation can affect the germline-competence of Embryonic Stem cell(ES cell) lines by accumulation of chromosome abnormalities and/or epigenetic alterations of the ES cell genome. The effectiveness of ES cell derivation is greatly strain-dependent and it may also influence the germline transmission capability.Recent technical improvements in the production of germline chimeras have been focused on means of generating ES cells lines with a higher germline potential.There are a number of options for generating chimeras from ES cells (ES chimera mice);however,each method has its advantages and disadvantages.Recent developments in induced pluripotent stem(iPS)cell technology have opened new avenues for generation of animals from genetically modified somatic cells by means of chimera technologies.The aim of this review is to give a brief account of how the factors mentioned above are influencing the germline transmission capacity and the developmental potential of mouse pluripotent stem cell lines.The most recent methods for generating specifically ES and iPS chimera mice,including the advantages and disadvantages of each method are also discussed.

Germline mutations in hereditary diffuse gastric cancer

Gastric cancer is one of the leading causes of cancer-related deaths worldwide. Among which, about 1%–3% of gastric cancer patients were characterized by inherited gastric cancer predisposition syndromes, knowing as hereditary diffuse gastric cancer（HDGC）. Studies reported that CDH1 germline mutations are the main cause of HDGC. With the help of rapid development of genetic testing technologies and data analysis tools, more and more researchers focus on seeking candidate susceptibility genes for hereditary cancer syndromes. In addition, National Comprehensive Cancer Network（NCCN） guidelines recommend that the patients of HDGC carrying CDH1 mutations should undergo prophylactic gastrectomy or routine endoscopic surveillances. Therefore, genetic counseling plays a key role in helping individuals with pathogenic mutations make appropriate risk management plans. Moreover, experienced and professional genetic counselors as well as a systematic multidisciplinary team（MDT） are also required to facilitate the development of genetic counseling and benefit pathogenic mutation carriers who are in need of regular and standardized risk management solutions. In this review, we provided an overview about the germline mutations of several genes identified in HDGC, suggesting that these genes may potentially act as susceptibility genes for this malignant cancer syndrome. Furthermore, we introduced information for prevention, diagnosis and risk management of HDGC. Investigations on key factors that may have effect on risk management decision-making and genetic data collection of more cancer syndrome family pedigrees are required for the development of HDGC therapeutic strategies.

An efficient strategy for generation of transgenic mice by lentiviral transduction of male germline stem cells in vivo

Background： Male germline stem cells（MGSCs） are a subpopulation of germ cells in the testis tissue. MGSCs are capable of differentiation into spermatozoa and thus are perfect targets for genomic manipulation to generate transgenic animals.Method： The present study was to optimize a protocol of production of transgenic mice through transduction of MGSCs in vivo using lentiviral-based vectors. The recombinant lentiviral vectors with either EF-1 or CMV promoter to drive the expression of enhanced green fluorescent protein（e GFP） transgene were injected into seminiferous tubules or inter-tubular space of 7-day-old and 28-day-old mouse testes. At 5 or 6 wk post-surgery, these pre-founders were mated with wild-type C57BL/6J female mice（1.5 to 2.0-month-old）.Results： Sixty-seven percent of F1 generation and 55.56 % of F2 offspring were positive for eG FP transgene under the control of EF-1 promoter via PCR analysis. The transgenic pups were generated in an injection site-and age-independent manner. The expression of transgene was displayed in the progeny derived from lentiviral vector containing CMV promoter to drive transgene, but it was silenced or undetectable in the offspring derived from lentiviral vector with transgene under EF-1 promoter. The methylation level of g DNA in the promoter region of transgene was much higher in the samples derived lentiviral vectors with EF-1 promoter than that with CMV promoter,suggesting e GFP transgene was suppressed by DNA methylation in vivo.Conclusion： This research reported here an effective strategy for generation of transgenic mice through transduction of MGSCs in vivo using lentivirus vectors with specific promoters, and the transgenic offspring were obtained in an injection site-and age-independent manner. This protocol could be applied to other animal species, leading to advancement of animal transgenesis in agricultural and biomedical fields.