Identification and interruption of inheritance of familial cryptic translocations: A case report.

BACKGROUND: Cryptic translocations can be identified via genetic analysis of aborted tissues or malformed infants, but it is difficult to deduce the parental origins of the translocations. In the absence of such information, it is not easy to distinguish translocations from normal embryos during pre-implantation genetic testing, that seeks to block familial transmission of translocations. METHODS: Here, we present a new method that detects cryptic translocations and blocks familial transmission thereof. Whole-genome, low-coverage mate-pair sequencing (WGLMPS) revealed chromosome breakpoint sequences, and preimplantation genetic haplotyping (PGH) was then used to discard embryos with cryptic translocations. RESULTS: Cryptic translocations were found in all four families, and familial transmission was successfully blocked in one family. CONCLUSION: Whole-genome, low-coverage mate-pair sequencing combined with preimplantation genetic haplotyping methods powerfully and practically identify cryptic translocations and block familial transmissions.

Systematic analysis of microbiota in pregnant Chinese women and its association with miscarriage.

Background: Miscarriage is the most common adverse pregnancy outcome and more than 50% of its incidence remains unexplained. Earlier studies have suggested that maternal microbiota might be associated with miscarriage, but the association is insufficiently understood. Methods: We used 16S ribosomal RNA (rRNA) amplicon sequencing and metagenomic sequencing technology to characterize the bacterial composition of three sites including the rectum, vagina, and cervix of a case group of 63 pregnant women who had miscarried compared to a control group of 24 pregnant women who underwent voluntary elective abortion. Results: The alpha-diversity from the rectum and cervix was significantly decreased in the case group relative to the control group. However, we did not find significant differences in microbial diversity of vaginal samples between the two groups. Lactobacillus was the most predominant genus in the cervix and vaginal samples. Gestational age at the time of surgery was positively associated with the rectum microbiota diversity, with an effect size of 10% (P=0.004). Host factors including gestational age and red blood count (RBC) were associated with the rectal microbiota diversity. Conclusions: We detected a significantly lower rectal microbiota diversity and a pro-inflammatory tendency in the miscarriage group. This is the first study to investigate the association of microbiota from samples collected from three sites and miscarriage. Further studies are warranted to explore further the role of microbiota in miscarriage.

Highly precise breakpoint detection of chromosome balanced translocation in chronic myelogenous leukaemia: Case series.

Chronic myelogenous leukaemia (CML) has a special phenomenon of chromosome translocation, which is called Philadelphia chromosome translocation. However, the detailed connection of this structure is troublesome and expensive to be identified. Low-coverage whole genome sequencing (LCWGS) could not only detect the previously unknown chromosomal translocation, but also provide the breakpoint candidate small region (with an accuracy of ±200 bases). Importantly, the sequencing cost of LCWGS is about US$300. Then, with the Sanger DNA sequencing, the precise breakpoint can be determined at a single base level. In our project, with LCWGS, BCR and ABL1 are successfully identified to be disrupted in three CML patients (at chr22:23,632,356 and chr9:133,590,450; chr22:23,633,748 and chr9:133,635,781; chr22: 23,631,831 and chr9:133,598,513, respectively). Due to the reconnection after chromosome breakage, classical fusion gene (BCR::ABL1) was found in bone marrow and peripheral blood. The precise breakpoints were helpful to investigate the pathogenic mechanism of CML and could better guide the classification of CML subtypes. This LCWGS method is universal and can be used to detect all diseases related to chromosome variation, such as solid tumours, liquid tumours and birth defects.

Analysis of complex chromosomal rearrangements using a combination of current molecular cytogenetic techniques.

BACKGROUND: Using combined fluorescence in situ hybridization (FISH) and high-throughput whole-genome sequencing (WGS) molecular cytogenetic technology, we aim to analyze the junction breakpoints of complex chromosome rearrangements (CCR) that were difficult to identify by conventional karyotyping analysis and further characterize the genetic causes of recurrent spontaneous abortion. RESULTS: By leveraging a combination of current molecular techniques, including chromosome karyotype analysis, FISH, and WGS, we comprehensively characterized the extremely complex chromosomal abnormalities in this patient with recurrent spontaneous abortions. Here, we demonstrated that combining these current established molecular techniques is an effective and efficient workflow to identify the structural abnormalities of complex chromosomes and locate the rearrangement of DNA fragments. CONCLUSIONS: In conclusion, leveraging results from multiple molecular and cytogenetic techniques can provide the most comprehensive genetic analysis for genetic etiology research, diagnosis, and genetic counseling for patients with recurrent spontaneous abortion and embryonic abortion.

A de novo 10q11.23q22.1 deletion detected by whole genome mate-pair sequencing: a case report.

BACKGROUND: Interstitial deletions of chromosome band 10q11-q22 was a genomic disorder distinguished by developmental delay, congenital cleft palate and muscular hypotonia. The phenotypes involved were heterogeneous, hinge on the variable breakpoints and size. CASE PRESENTATION: Here, we presented a patient with soft palate cleft, growth and development delay. The patient was a 2 years and 5 months girl who was not able to walk unless using a children's crutches to support herself. Whole-exome sequencing (WES) and whole-genome mate-pair sequencing (WGMS) were both performed by next generation sequencing (NGS). A 20.76 Mb deletion at 10q11.23q22.1 (seq[GRCh37/hg19]del(10)(50,319,387-71,083,899) × 1) was revealed by the WGMS, which was verified as de novo by quantitative polymerase chain reaction (QPCR). CONCLUSION: Children with 10q11-q22 deletions greater than 20 MB have never been reported before, and we are the first to report and provide a detailed clinical phenotype, which brings further knowledge of 10q11-q22 deletions.

Successful birth after preimplantation genetic testing for a couple with two different reciprocal translocations and review of the literature.

BACKGROUND: Preimplantation genetic testing for chromosomal structural rearrangements (PGT-SR) is widely applied in couples with single reciprocal translocation to increase the chance for a healthy live birth. However, limited knowledge is known on the data of PGT-SR when both parents have a reciprocal translocation. Here, we for the first time present a rare instance of PGT-SR for a non-consanguineous couple in which both parents carried an independent balanced reciprocal translocation and show how relevant genetic counseling data can be generated. METHODS: The precise translocation breakpoints were identified by whole genome low-coverage sequencing (WGLCS) and Sanger sequencing. Next-generation sequencing (NGS) combining with breakpoint-specific polymerase chain reaction (PCR) was used to define 24-chromosome and the carrier status of the euploid embryos. RESULTS: Surprisingly, 2 out of 3 day-5 blastocysts were found to be balanced for maternal reciprocal translocation while being normal for paternal translocation and thus transferable. The transferable embryo rate was significantly higher than that which would be expected theoretically. Transfer of one balanced embryo resulted in the birth of a healthy boy. CONCLUSION(S): Our data of PGT-SR together with a systematic review of the literature should help in providing couples carrying two different reciprocal translocations undergoing PGT-SR with more appropriate genetic counseling.

Breakpoints Identification of a Balanced Complex Chromosome Rearrangement Case: 46,XX, t(6;15;10;9)(q13;q15;p11.2;q34.3) ins(9;8)(q22.33;q21.1q21.3).

BACKGROUND: Balanced complex chromosome rearrangement (CCR) carriers are phenotypically normal but at high risk of reproductive failure, recurrent miscarriages, and affected offspring, so that cytogenetic characterizations of CCR carriers are crucial. METHODS: We report a case of CCR: 46,XX, t(6;15;10;9)(q13;q15;p11.2;q34.3) ins(9;8)(q22.33;q21.1q21.3). The peripheral blood was collected for karyotyping, single nucleotide polymorphism array (SNP-array) analysis, and whole genome mate-pair sequencing. RESULTS: The patient's karyotype is detected and identified as 46,XX, t(6;15;10;9)(q13;q15;p11.2;q34.3) ins(9;8) (q22.33;q21.1q21.3), with no significant duplication and deletion found by SNP-array analysis. There are 16 break-points among chromosomes 6, 8, 9, 10, and 15 identified by whole genome sequencing. CONCLUSIONS: With a variety of detection techniques, we can deeply study the genetic characteristics of CCRs, thus providing a basis for genetic counseling and choice of fertility.

A case report of congenital idiopathic hypogonadotropic hypogonadism caused by novel mutation of GNRHR gene.

RATIONALE: This study aimed to investigate the genetic mutation characteristics of congenital idiopathic hypogonadotropic hypogonadism (IHH) through the clinical features and genetic analysis of 2 patients with IHH in 1 pedigree. PATIENT CONCERNS: A 23-year-old girl presented with primary amenorrhea, sparse pubic hair, lack of breast development, and delayed sexual development. DIAGNOSES: Combined with the clinical characteristics, auxiliary examinations, and molecular genetic analysis, the patient was diagnosed as IHH. INTERVENTIONS: Whole exome and Sanger sequencing were performed to validate the mutation in family members. OUTCOMES: A novel homozygous missense mutation c.521A > G (p.Q174R) in the GNRHR gene was identified in the 2 affected sisters. Familial segregation showed that the homozygous variant was inherited from their parents respectively and the eldest sister was the carrier without correlative symptom. LESSONS: We reported a novel GNRHR mutation in a pedigree with congenital idiopathic hypogonadotropic hypogonadism. Glutamine at amino acid position 174 was highly conserved among various species. The molecular structure of GNRHR protein showed that p.Q174R mutation brought in a new stable hydrogen bond between position 174 and 215, may impede conformational mobility of the TMD4 and TMD5. It suggests that the missense mutation c.521A > G related to congenital idiopathic hypogonadotropic hypogonadism was probably a causative factor for both sisters. Through high-throughput sequencing and experimental verification, we had basically determined the patient's pathogenic mutation and inheritance, which could better guide doctors for treatment.

Successful pregnancy after prenatal diagnosis by NGS for a carrier of complex chromosome rearrangements.

BACKGROUND: The study is aimed to provide prediction for fertility risk in the setting of assisted reproduction for a woman with complex chromosomal rearrangements (CCRs). METHODS: We implemented a robust approach, which combined whole-genome low-coverage mate-pair sequencing (WGL-MPS), junction-spanning PCR and preimplantation genetic testing for aneuploidy (PGT-A) method to provide accurate chromosome breakpoint junctional sequences in the embryo selection process in the setting of assisted reproduction for a couple with recurrent abortions due to CCRs. RESULT: WGL-MPS was applied to a female carrying CCRs which consisted of 9 breakpoints and 1 cryptic deletion related to fertility risks. Sequencing data provided crucial information for designing junction-spanning PCR and PGT-A process, which was performed on the 11 embryos cultivated. One embryo was considered qualified for transplanting, which carried the exact same CCRs as the female carrier, whose phenotype was normal. The amniotic fluid was also investigated by WGL-MPS and karyotyping at 19 weeks' gestation, which verified the results that the baby carried the same CCRs. A healthy baby was born at 39 weeks' gestation by vaginal delivery. CONCLUSION(S): Our study illustrates the WGL-MPS approach combining with junction-spanning PCR and PGT-A is a powerful and practical method in the setting of assisted reproduction for couples with recurrent miscarriage due to chromosomal abnormalities, especially CCRs carriers.

Screening of triploid with low-coverage whole-genome sequencing by a single-nucleotide polymorphism-based test in miscarriage tissue.

PURPOSE: To establish a single-nucleotide polymorphism-based analysis (SBA) method to identify triploidy in the miscarriage tissue by using low-coverage whole-genome sequencing (LC-WGS). METHODS: The method was established by fitting a quadratic curve model by counting the distribution of three heterozygous mutation content intervals. The triploid test result was mainly determined by the opening direction and the axis of symmetry of the quadratic curve, and Z test between the same batch samples was also used for auxiliary judgment. RESULTS: Two hundred thirteen diploid samples and 8 triploid samples were used for establishment of the analytical method and 203 unknown samples were used for blind testing. In the blind testing, we found 2 cases positive for triploidy. After chromosome microarray analysis (CMA) and mass spectrometry verification, we found that both samples were true positives. We randomly selected 5 samples from the negative samples for mass spectrometry verification, and the results showed that these samples were all true negatives. CONCLUSIONS: Our method achieved accurate detection of triploidy in the miscarriage tissue and has the potential to detect more chromosomal abnormality types such as uniparental disomy (UPD) using a single LC-WGS approach.

Serum CEA and CA19-9 Levels are Associated with the Presence and Severity of Colorectal Neoplasia.

BACKGROUND: High concentrations of carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were found in the serum of patients with colon cancer. We performed the present work to investigate the association between elevated levels of serum biomarkers (CEA and CA19-9) and shortened survival in patients with colon cancer. METHODS: We examined patients who underwent colonoscopies between 2001 and 2014 and measured and analyzed the serum CEA and CA19-9 levels of 362 participants. RESULTS: Elevated CEA concentrations were found to be associated with advanced invasion, lymph node metastasis, and short survival. Elevated CA19-9 concentrations also were associated with lymph node metastasis and short survival. CONCLUSIONS: Elevated serum CEA or CA19-9 levels were found to be associated with shortened survival.

Maternal interchromosomal insertional translocation leading to 1q43-q44 deletion and duplication in two siblings.

BACKGROUND: 1q43-q44 deletion syndrome is a well-defined chromosomal disorder which is characterized by moderate to severe mental retardation, and variable but characteristic facial features determined by the size of the segment and the number of genes involved. However, patients with 1q43-q44 duplication with a clinical phenotype comparable to that of 1q43-q44 deletion are rarely reported. Moreover, pure 1q43-q44 deletions and duplications derived from balanced insertional translocation within the same family with precisely identified breakpoints have not been reported. CASE PRESENTATION: The proband is a 6-year-old girl with profound developmental delay, mental retardation, microcephaly, epilepsy, agenesis of the corpus callosum and hearing impairment. Her younger brother is a 3-month-old boy with macrocephaly and mild developmental delay in gross motor functions. G-banding analysis of the subjects at the 400-band level did not reveal any subtle structural changes in their karyotypes. However, single-nucleotide polymorphism (SNP) array analysis showed a deletion and a duplication of approximately 6.0 Mb at 1q43-q44 in the proband and her younger brother, respectively. The Levicare analysis pipeline of whole-genome sequencing (WGS) further demonstrated that a segment of 1q43-q44 was inserted at 14q23.1 in the unaffected mother, which indicated that the mother was a carrier of a 46,XX,ins(14;1)(q23.1;q43q44) insertional translocation. Moreover, Sanger sequencing was used to assist the mapping of the breakpoints and the final validation of those breakpoints. The breakpoint on chromosome 1 disrupted the EFCAB2 gene in the first intron, and the breakpoint on chromosome 14 disrupted the PRKCH gene within the 12th intron. In addition, fluorescence in situ hybridization (FISH) further confirmed that the unaffected older sister of the proband carried the same karyotype as the mother. CONCLUSION: Here, we describe a rare family exhibiting pure 1q43-q44 deletion and duplication in two siblings caused by a maternal balanced insertional translocation. Our study demonstrates that WGS with a carefully designed analysis pipeline is a powerful tool for identifying cryptic genomic balanced translocations and mapping the breakpoints at the nucleotide level and could be an effective method for explaining the relationship between karyotype and phenotype.

Breakpoints and deleted genes identification of ring chromosome 18 in a Chinese girl by whole-genome low-coverage sequencing: a case report study.

BACKGROUND: Ring chromosome 18 [r(18)] is formed by 18p- and 18q- partial deletion and generates a ring chromosome. Loss of critical genes on each arm of chromosome 18 may contribute to the specific phenotype, and the clinical spectrum varieties may heavily depend on the extent of the genomic deletion. The aim of this study is to identify the detailed breakpoints location and the deleted genes result from the r18. CASE PRESENTATION: Here we describe a detailed diagnosis of a seven-year-old Chinese girl with a ring chromosome 18 mutation by a high-throughput whole-genome low-coverage sequencing approach without karyotyping and other cytogenetic analysis. This method revealed two fragment heterozygous deletions of 18p and 18q, and further localized the detailed breakpoint sites and fusion, as well as the deleted genes. CONCLUSIONS: To our knowledge, this is the first report of a ring chromosome 18 patient in China analyzed by whole-genome low-coverage sequencing approach. Detailed breakpoints location and deleted genes identification help to estimate the risk of the disease in the future. The data and analysis here demonstrated the feasibility of next-generation sequencing technologies for chromosome structure variation including ring chromosome in an efficient and cost effective way.

Mapping Breakpoints of Complex Chromosome Rearrangements Involving a Partial Trisomy 15q23.1-q26.2 Revealed by Next Generation Sequencing and Conventional Techniques.

Complex chromosome rearrangements (CCRs), which are rather rare in the whole population, may be associated with aberrant phenotypes. Next-generation sequencing (NGS) and conventional techniques, could be used to reveal specific CCRs for better genetic counseling. We report the CCRs of a girl and her mother, which were identified using a combination of NGS and conventional techniques including G-banding, fluorescence in situ hybridization (FISH) and PCR. The girl demonstrated CCRs involving chromosomes 3 and 8, while the CCRs of her mother involved chromosomes 3, 5, 8, 11 and 15. HumanCytoSNP-12 Chip analysis identified a 35.4 Mb duplication on chromosome 15q21.3-q26.2 in the proband and a 1.6 Mb microdeletion at chromosome 15q21.3 in her mother. The proband inherited the rearranged chromosomes 3 and 8 from her mother, and the duplicated region on chromosome 15 of the proband was inherited from the mother. Approximately one hundred genes were identified in the 15q21.3-q26.2 duplicated region of the proband. In particular, TPM1, SMAD6, SMAD3, and HCN4 may be associated with her heart defects, and HEXA, KIF7, and IDH2 are responsible for her developmental and mental retardation. In addition, we suggest that a microdeletion on the 15q21.3 region of the mother, which involved TCF2, TCF12, ADMA10 and AQP9, might be associated with mental retardation. We delineate the precise structures of the derivative chromosomes, chromosome duplication origin and possible molecular mechanisms for aberrant phenotypes by combining NGS data with conventional techniques.

Intragenic and extragenic disruptions of FOXL2 mapped by whole genome low-coverage sequencing in two BPES families with chromosome reciprocal translocation.

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal dominant disorder that affects craniofacial development and ovarian function. FOXL2 is the only gene known to be responsible for BPES. The majority of BPES patients show intragenic mutations of FOXL2. Recently, a 7.4 kb sequence disruption, which was 283 kb upstream of FOXL2, was identified to independently contribute to the BPES phenotype. Several breakpoints nearing FOXL2 (0 Mb to 1.2 Mb, several of which were distant from the 7.4 kb sequence disruption) have been mapped or deduced through a traditional method in BPES patients with chromosome reciprocal translocation. In this study, two BPES families with chromosome reciprocal translocation were investigated. Intragenic mutations of FOXL2 or pathogenic copy number variations were excluded for the two BPES families. All of the four breakpoints were identified at a base-precise manner using Giemsa banding and whole genome low-coverage sequencing (WGLCS). In family 01, the breakpoints were found at chr1:95,609,998 and chr3:138,879, 114 (213,132 bp upstream of FOXL2). In family 02, the breakpoints were located at chr3:138,665,431 (intragenic disruptions of FOXL2) and chr20:56,924,609. Results indicate that the intragenic and extragenic interruptions of FOXL2 can be accurately and rapidly detected using WGLCS. In addition, both the 213 kb upstream and intragenic interruptions of FOXL2 can cause BPES phenotype.

Mapping breakpoints of a familial chromosome insertion (18,7) (q22.1; q36.2q21.11) to DPP6 and CACNA2D1 genes in an azoospermic male.

It is widely accepted that the incidence of chromosomal aberration is 10-15.2% in the azoospermic male; however, the exact genetic damages are currently unknown for more than 40% of azoospermia. To elucidate the causative gene defects, we used the next generation sequencing (NGS) to map the breakpoints of a chromosome insertion from an azoospermic male who carries a balanced, maternally inherited karyotype 46, XY, inv ins (18,7) (q22.1; q36.2q21.11). The analysis revealed that the breakage in chromosome 7 disrupts two genes, dipeptidyl aminopeptidase-like protein 6 (DPP6) and contactin-associated protein-like 2 (CACNA2D1), the former participates in regulation of voltage-gated potassium channels, and the latter is one of the components in voltage-gated calcium channels. The deletion and duplication were not identified equal or beyond 100 kb, but 4 homologous DNA elements were verified proximal to the breakpoints. One of the proband's sisters inherited the same aberrant karyotype and experienced recurrent miscarriages and consecutive fetus death, while in contrast, another sister with a normal karyotype experienced normal labor and gave birth to healthy babies. The insertional translocation is confirmed with FISH and the Y-chromosome microdeletions were excluded by genetic testing. This is the first report describing chromosome insertion inv ins (18,7) and attributes DPP6 and CACNA2D1 to azoospermia.

A robust approach for blind detection of balanced chromosomal rearrangements with whole-genome low-coverage sequencing.

Balanced chromosomal rearrangement (or balanced chromosome abnormality, BCA) is a common chromosomal structural variation. Next-generation sequencing has been reported to detect BCA-associated breakpoints with the aid of karyotyping. However, the complications associated with this approach and the requirement for cytogenetics information has limited its application. Here, we provide a whole-genome low-coverage sequencing approach to detect BCA events independent of knowing the affected regions and with low false positives. First, six samples containing BCAs were used to establish a detection protocol and assess the efficacy of different library construction approaches. By clustering anomalous read pairs and filtering out the false-positive results with a control cohort and the concomitant mapping information, we could directly detect BCA events for each sample. Through optimizing the read depth, BCAs in all samples could be blindly detected with only 120 million read pairs per sample for data from a small-insert library and 30 million per sample for data from nonsize-selected mate-pair library. This approach was further validated using another 13 samples that contained BCAs. Our approach advances the application of high-throughput whole-genome low-coverage analysis for robust BCA detection-especially for clinical samples-without the need for karyotyping.

Complete genome sequencing and variant analysis of a Pakistani individual.

We sequenced the genome of a Pakistani male at 25.5x coverage using massively parallel sequencing technology. More than 90% of the sequence reads were mapped to the human reference genome. In subsequent analysis, we identified 3,224,311 single-nucleotide polymorphisms (SNPs), of which 388,532 (12% of the total SNPs) had not been previously recorded in single nucleotide polymorphism database (dbSNP) or the 1000 Genomes Project database. The 5991 non-synonymous coding variants were screened for deleterious or disease-associated SNPs. Analysis of genes with deleterious SNPs identified 'retinoic acid signaling' and 'regulation of transcription' as the enriched Gene Ontology terms. Scanning of non-synonymous SNPs against the OMIM revealed several disease and phenotype-associated variants in Pakistani genome. Comparative analysis with Indian genome sequence revealed >1.8 million shared SNPs; 32% of which were annotated in ~14,000 genes. Gene Ontology (GO) terms analysis of these genes identified 'response to jasmonic acid stimulus', 'aminoglycoside antibiotic metabolic process' and 'glycoside metabolic process' with considerable enrichment. A total of 59,558 of small indels (1-5 bp) and 16,063 large structural variations were found; 54% of which was novel. Substantial number of novel structural variations discovered in Pakistani genome enforced previous inferences that (a) structural variations are major type of variation in the genome and (b) compared with SNPs, they putatively exhibit equivalent or superior functional roles. This genome sequence information will be an important reference for population-wide genomics studies of ethnically diverse South Asian subcontinent.