Theoretically, microduplication of chromosomal region 22q11.2, which is rich in segmental duplications, should be as frequent as microdeletions of the same region. Preliminary analysis on the rarity of reports for 22q11.2 microduplication in the literature has suggested that, for the discovery of 22q11.2 microduplication, there has been a lack of sensitivity for routine diagnostic techniques such as karyotyping, PCR and FISH. On the other hand, the diverse anomalies and extremely variable phenotypes of carriers also implied great difficulties one has to face upon clinical consultation. Genetics as well as clinical problems in connection with 22q11.2 microduplication has vividly illustrated the great challenge for the interpretation of genotype-phenotype correlation, and thereby posed yet another gray zone for clinical genetics research.
Chromosome Deletion ; Chromosomes, Human, Pair 22 ; genetics ; Gene Duplication ; Genetics, Medical ; Humans ; Phenotype

OBJECTIVETo explore the implications of copy number variations (CNVs) for congenital heart diseases (CHD) in fetuses.

METHODSG-banding karyotype analysis and next-generation sequencing (NGS) technology were performed on cord blood samples derived from 36 fetuses with CHD. Pathological implication of the CNVs was explored through comparison against the International Genomic Polymorphism Database (http://www.ebi.ac.uk/dgva/), Phenotype Database (http://decipher.sanger.ac.uk/), and the Human Genome Database at UCSC (http://genome.ucsc.edu/cgi-bin/hgGateway).

RESULTSG-banding karyotype analysis has identified 7 chromosomal abnormalities. For the remaining 28 cases, NGS has identified 4 microdeletions and microduplications, which involved chromosomes 2, 13, 14, 16 and 22. The largest involved a 6.8 Mb microdeletion, while the smallest involved a 280 kb microduplication. The chromosomal breakpoints in 1 case were delineated. One case of Noonan syndrome and one case of 22q11.2 deletion were diagnosed.

CONCLUSIONNGS can accurately determine the origins of derivative chromosomes and facilitate identification of pathogenic CNVs/genes. It can serve as a useful complement for conventional G-banding and reduce the recurrence risk.

Chromosome Aberrations ; Chromosome Banding ; methods ; DNA Copy Number Variations ; genetics ; Fetus ; abnormalities ; Heart Defects, Congenital ; genetics ; High-Throughput Nucleotide Sequencing ; methods ; Humans ; Karyotyping ; methods

OBJECTIVE: To carry out genetic testing for an abortus suspected with Cornelia de Lange syndrome (CdLS). METHODS: History of gestation and the family was taken. Combined with prenatal ultrasonography and the phenotype of the abortus, a diagnosis was made for the proband. Fetal tissue and peripheral blood samples of its parents were collected for the extraction of genomic DNA. Whole exome sequencing was carried out to detect mutations related to the phenotype. Suspected mutations were verified in the parents through Sanger sequencing. RESULTS: Prenatal ultrasound found that the forearms and hands of the fetus were anomalous, in addition with poorly formed vermis cerebellum, slight micrognathia, and increased echo of bilateral renal parenchyma. Examination of the abortus has noted upper limb and facial malformations. Whole exome sequencing revealed that the fetus carried a heterozygous c.2118delG (p.Lys706fs) frameshift mutation of the NIPBL gene. The same mutation was not found in either parent. CONCLUSION The heterozygous c.2118delG (p.Lys706fs) frameshift mutation of the NIPBL gene probably underlies the CdLS in the fetus. Above finding has provided a basis for the genetic counseling for the family.
Cell Cycle Proteins/genetics* ; DNA Mutational Analysis ; De Lange Syndrome/pathology* ; Female ; Fetus ; Humans ; Male ; Mutation ; Phenotype ; Pregnancy ; Whole Exome Sequencing

OBJECTIVE: To analyze the clinical phenotype and genetic characterization of a child with early infantile epileptic encephalopathy. METHODS: The proband was subjected to history taking and was diagnosed based on his clinical manifestation, magnetic resonance imaging (MRI) and whole exome sequencing (WES). Sanger sequencing was carried out to determine the origin of pathogenic variant. RESULTS: The proband unconsciously tilts his head to one side with squint, which revealed an abnormal discharge. MRI indicated suspicious abnormal signal shadow in the left posterior frontal cortex in addition with inflammation signs in the right maxillary sinus and ethmoid sinus. WES revealed that the proband has carried a heterozygous c.5789G>A variant in the CACNAIA gene. The result of Sanger sequencing was in keeping with that of WES. Neither of his parents has carried the same variant. CONCLUSION The heterozygous c.5789G>A variant of the CACNAIA gene probably underlay the early infantile epileptic encephalopathy 42 in the proband, which has a de novo origin.
Calcium Channels/genetics* ; Genetic Testing ; Heterozygote ; Humans ; Infant ; Mutation ; Spasms, Infantile/genetics* ; Whole Exome Sequencing

The ongoing development of high-throughput sequencing technology and continuous decline of sequencing cost have made it possible to carry out large-scale screening for genetic diseases, which are the main component of birth defects. The screening of genetic diseases is expected to significantly reduce the rate of birth defects and the burden of genetic diseases to the affected families and the society. Taking Down syndrome as an example, through the analysis of the cost-benefit ratio of relevant screening programs, this article has summarized the socio-economic indicators to be considered during the design and development of genetic disease screening.
Cost-Benefit Analysis ; Down Syndrome/genetics* ; Genetic Testing ; Humans

OBJECTIVETo detect mutation of GPR143 gene in a Chinese patient affected with ocular albinism.

METHODSPeripheral blood samples were collected from the proband and his parents. The coding regions of the GPR143 gene were subjected to PCR amplification and Sanger sequencing.

RESULTSA previously unreported mutation (c.758T>A) was found in exon 6 of the GPR143 gene in the proband and his mother. The same mutation was not found in his father. As predicted, the mutation has resulted in a stop codon, causing premature termination of protein translation.

CONCLUSIONA novel mutation of the GPR143 gene related to X-linked ocular albinism has been identified.

Adult ; Albinism, Ocular ; genetics ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Eye Proteins ; genetics ; Female ; Genetic Diseases, X-Linked ; genetics ; Humans ; Infant ; Male ; Membrane Glycoproteins ; genetics ; Molecular Sequence Data ; Mutation

OBJECTIVETo analyze the expression of genes from chromosomal region 22q11.2 and assess the association between mutation(s) of particular gene(s) from this region and malformations of the urinary system.

METHODSExpression of rat homologs of 33 genes from above region was determined in kidney tissues derived from rats of different fetal development ages (E13, E15, E19) and adulthood with reverse transcriptase-PCR. Potential mutation(s) in candidate gene SNAP29, whose expression pattern appeared to be unique, was screened in 44 patients and 220 normal controls with PCR-single strand conformation polymorphism (SSCP). Suspected positive regions were sequenced to verify the mutations.

RESULTSNine genes showed no expression throughout the whole development process; 18 genes with various expression levels showed continuous expression from the beginning of development; 6 genes only expressed for a short time, among which SNAP29 was selected for mutation screening. Upon sequencing, three mutations were identified from the 44 patients, including a G to A transition (GAG to AAG) in exon 2, and two A to G transitions (AGC to GGC) in exon 3.

CONCLUSIONThrough systematic analysis of the expression of genes from chromosomal region 22q11.2, the SNAP29 gene was found to have a potential role in the development of genitourinary system. Two missense mutations were identified in three patients. These included one in exon 2 (featuring cryptorchidism), and the other in exon 3 (featuring cryptorchidism and hypospadia). Neither of the mutations was found in the normal controls. The results suggested that mutation(s) of gene(s) from chromosomal region 22q11.2 may play an important role in the genesis of genitourinary malformations.

Animals ; DNA Mutational Analysis ; methods ; Exons ; genetics ; Female ; Humans ; Male ; Membrane Glycoproteins ; Membrane Proteins ; genetics ; Mice ; Platelet Glycoprotein GPIb-IX Complex ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Polymorphism, Single-Stranded Conformational ; Qb-SNARE Proteins ; genetics ; Qc-SNARE Proteins ; genetics ; Urogenital Abnormalities ; genetics

OBJECTIVE: To identify the pathogenic variant for a husband with osteogenesis imperfecta and provide preimplantation genetic testing (PGT) for the couple. METHODS: High-throughput sequencing and Sanger sequencing were carried out to identify the pathologic variant in the husband patients. PGT of embryos was performed through direct detection of the mutation site. Meanwhile, chromosome aneuploidy of the blastocysts was screened. Following transplantation, cytogenetic and genetic testing of fetal amniotic fluid sample was carried out during mid-pregnancy. Chromosome copy number variant (CNV) was detected at multiple sites of the placenta after delivery. RESULTS: The husband was found to harbor heterozygous c.544-2A>G variant of the COL1A1 gene. The same variant was not detected in either of his parents. PGT revealed that out of three embryos of the couple, one was wild-type for the c.544-2A site but mosaicism for duplication of 16p13.3.11.2. The other two embryos were both heterozygous for the c.544-2A>G variant. Following adequate genetic counseling, the wild-type embryo was transplanted. Amniotic fluid testing confirmed that the fetus had normal chromosomes and did not carry the c.544-2A>G variant. The copy number of chromosomes at different parts of placenta was normal after birth. CONCLUSION For couples affected with monogenic disorders, e.g., osteogenesis imperfecta, direct detection of the mutation site may be used for PGT after identifying the pathogenic variant. After adequate genetic counseling, prenatal diagnosis must be carried out to ensure the result.
Aneuploidy ; China ; Female ; Genetic Testing ; Humans ; Osteogenesis Imperfecta/genetics* ; Pregnancy ; Preimplantation Diagnosis

OBJECTIVE: To apply nanopore third-generation sequencing for the detection of chromosomal aneuploidy samples, and explore its performance and application prospects. METHODS: DNA extracted from two human cell lines with X chromosome monosomy and 22.5 Mb deletion in 7q11.23-q21.3 region was sequenced with a MinION sequencer, and the results were analyzed. RESULTS: Respectively, 555 872 and 2 679 882 reads were obtained from the two samples within 24 hours, with genome coverage being 53.75% and 88.63%. With a sequencing depth of 0.81× and 2.40× , respectively, the abnormal chromosomal regions could be detected by comparative analysis using Minimap2. CONCLUSION With low-depth whole genome sequencing, the use of nanopore third-generation sequencing is expected to complete the detection and analysis of chromosomal aneuploidy samples within 24 hours, but its further application and promotion needs to overcome the cost constraints.
Aneuploidy ; Chromosomes ; High-Throughput Nucleotide Sequencing ; Humans ; Sequence Analysis, DNA ; Technology

OBJECTIVE: To diagnose a fetus with Papillorenal syndrome by prenatal ultrasonography and genetic testing, and to correlate its genotype with phenotype. METHODS: Ultrasound finding of the fetus was reviewed. Muscle sample of the abortus was taken, and genetic variant related to the clinical phenotype was screened by whole exome sequencing (WES). Suspected pathogenic variant was verified by Sanger sequencing. RESULTS: Prenatal ultrasound revealed severe dysplasia of the fetal kidneys and oligohydramnios. WES revealed that the fetus has carried a c.736G>T (p.Glu246Ter) nonsense variant of the PAX2 gene, which was unreported previously. The result of Sanger sequencing was consistent with that of WES. Both parents of the fetus were of the wild-type, suggesting a de novo origin of the fetal variant. CONCLUSION The novel heterozygous c.736G>T (p.Glu246Ter) variant of the PAX2 gene probably underlay the Papillorenal syndrome in the fetus. Above finding has provided a basis for genetic counseling and clinical decision-making.