RESUMO
Objective:To investigate the power and prenatal diagnosis strategies of cell-free fetal DNA (cffDNA) testing for chromosomal aneuploidy screening apart from trisomy-13/18/21.Methods:This study collected the clinical data of three cases at high risk of trisomy-16 indicated by cffDNA testing in Hunan Provincial Maternal and Child Health Care Hospital from March 2019 to March 2020. Results of the conventional G-banding karyotype analysis of amniotic fluid, single nucleotide polymorphism array (SNP-array) and low-coverage massively parallel copy number variation sequencing (CNV-seq) of placenta/fetal skin samples were analyzed.Results:(1) cffDNA testing results suggested that case 1-3 were at high risk of trisomy-16 and the Z values of chromosome 16 were 20.57, 24.88 and 17.87, respectively. (2) Karyotype analysis of amniotic fluid samples did not identify any abnormalities in Case 1 and 2, while SNP-array revealed a 19.2 Mb and 23.0 Mb heterozygous deletion at 16p13.3p12.3 and 16q22.1q24.3 in Case 1, and a 16.0 Mb loss of heterozygosity at 16q22.3q24.3 in Case 2. Case 3 had a mosaicism karyotype of 47,XY,+16[3]/46,XY[97] and SNP-array analysis showed no heterozygous deletion greater than 5 Mb or copy number variation. (3) Ultrasonography indicated fetal growth restriction in Case 1 and 2 and fetal death in Case 3. All three pregnancies were terminated. CNV-seq analysis of placental tissue in the center of both fetal and maternal side revealed mosaic trisomy 16, with the copy numbers of chromosome 16 of 2.56/2.70, 2.73/2.82, 2.80/2.81, respectively. However, no copy number variation was detected in Case 1 or 2 by CNV-seq analysis of fetal skin tissues. Conclusions:cffDNA testing has a certain power in detecting trisomy-16 apart from trisomy-13/18/21. For high-risk cases of trisomy-16 indicated by cffDNA testing, SNP-array analysis combined with karyotype analysis is suggested to rule out low-level mosaicism and loss of heterozygosity.
RESUMO
Advances in cell and molecular genetics have contributed to the development of human genetic re-search and personalized medicine. The enhanced capacity of the new DNA sequencing technologies, especially the high-throughput sequencing, is not only reducing the cost of sequencing but is also enabling some new questions. The potential utilization of whole exome sequencing ( WES) and whole genome sequencing ( WGS) is increasing in the research and clinical setting. And there is a potential for the genetic counselors' of recognition and reporting of incidental or secondary findings unrelated to the indication for ordering but of medical value for patient care, which inevitably create prominent legal and ethical issues. In addition, the internet increases the risk of private informa-tion and genetic information disclosure both for research and clinical practice. Moreover, these questions maybe more significant when commercial tests in multiplex genetic profiles are currently being provided to consumerswith-out the physicians' consultation, referred to as direct-to-consumer genetic tests ( DTCgt) . Existing laws, regula-tions and guidelines in China mostlycontrol and standardize technical aspects. Special regulations and rules for ge-netic arrangement and results explaining and interpretation remain needed; besides, the qualification of relevant personnel. The molecular genetic testing-related stakeholders include the providers, professional practitioners, and consumers &subjects, should realize these problems. Governments and professional organizations should produce policies, guidelines, and recommendations for the related stakeholders, such as testing providers andconsultants, to minimize the risks, and maximize the advantages of molecular genetic technologies, thus promote precision medi-cine and personalized therapy and disease prevention.
RESUMO
The present study focused on the characterization and genomic sequence of phage PS2 that infects Serratia marcescens clinical isolates.The morphology of phage PS2 was observed with electron microscope.The one-step growth curve,host range,and stability of PS2 were investigated.In addition,Phage DNA was extracted from the purified phage particles using a MiniBEST Viral RNA/DNA Extraction Kit.DNA sample was analyzed by digesting with restriction enzymes.The phage DNA was used for constructing the sequencing library.The library was sequenced on a MiSeqTM platform.The whole genome sequence was obtained by Velvet (version:1.2.08) assembling.Phage PS2 belongs to the Myoviridae family.The linear,circularly permuted,167 266-bp double-stranded DNA genome of PS2 has high similarities to T4-1ike phages.The phage DNA contains 41.7％ GC and 276 ORFs.PS2 exhibited a 21-minute latent period and 70 PFU per cell at burst size when the pathogenic S.marcescens strain S2 served as a host.Further investigation suggested that PS2 is stable in a wide pH range (pH5 to pH10) and at extreme temperatures (50 ℃ and 60 ℃) after incubation alone at different pHs and different temperatures,respectively.The paper focused on the isolation and identification of a novel lytic S.marcescens phage,the biological characteristics,the whole genome sequencing and the preliminary study of bioinformatics,which laid the foundation for deeply analysis to the phage therapy of multi-drug resistant bacteria and the phage biological information.
RESUMO
The present study focused on the characterization and genomic sequence of phage PS2 that infects Serratia marcescens clinical isolates.The morphology of phage PS2 was observed with electron microscope.The one-step growth curve,host range,and stability of PS2 were investigated.In addition,Phage DNA was extracted from the purified phage particles using a MiniBEST Viral RNA/DNA Extraction Kit.DNA sample was analyzed by digesting with restriction enzymes.The phage DNA was used for constructing the sequencing library.The library was sequenced on a MiSeqTM platform.The whole genome sequence was obtained by Velvet (version:1.2.08) assembling.Phage PS2 belongs to the Myoviridae family.The linear,circularly permuted,167 266-bp double-stranded DNA genome of PS2 has high similarities to T4-1ike phages.The phage DNA contains 41.7％ GC and 276 ORFs.PS2 exhibited a 21-minute latent period and 70 PFU per cell at burst size when the pathogenic S.marcescens strain S2 served as a host.Further investigation suggested that PS2 is stable in a wide pH range (pH5 to pH10) and at extreme temperatures (50 ℃ and 60 ℃) after incubation alone at different pHs and different temperatures,respectively.The paper focused on the isolation and identification of a novel lytic S.marcescens phage,the biological characteristics,the whole genome sequencing and the preliminary study of bioinformatics,which laid the foundation for deeply analysis to the phage therapy of multi-drug resistant bacteria and the phage biological information.