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Objective:To analyze fetal sex chromosome abnormalities in prenatal diagnosis based on amniotic fluid cell culture.Methods:Clinical data of 12 164 pregnant women who underwent amniocentesis in Maternal and Child Health Hospital of Hunan Province from January 2017 to December 2020 were retrospectively analyzed. For those diagnosed with fetal sex chromosome abnormalities, the results of karyotyping and chromosome microarray analysis (CMA) were analyzed and described.Results:(1) Among the 12 164 cases, fetal sex chromosome abnormalities were detected in 387 cases (3.2%), including 351 cases with abnormal sex chromosome karyotype and 36 with sex chromosome microdeletion/microduplication. (2) High-risk patients indicated by non-invasive prenatal test (NIPT) had the highest proportion of sex chromosomes abnormalities (74.2%, 287/387), followed by those with other ultrasound abnormalities (8.5%, 33/387), high risk of Down syndrome screening (7.0%, 27/387), advanced maternal age (4.7%, 18/387), history of adverse pregnant or delivery (3.3%, 13/387), and nuchal translucency thickening or cervical lymphatic hygroma (2.3%, 9/387). (3) Detected chromosome karyotype abnormalities included numerical abnormalities [73.2%(257/351)], mosaicism [18.8(66/351)], and structural abnormalities [8.0%(28/351)], among which, 47,XXY [46.7%(120/257)], 45,X/46,XX[48.5%(32/66)], and X chromosome deletion [39.3%(11/28)] were the most common, respectively. Among 36 sex chromosome microdeletions/microduplications cases, 15(41.7%) were with pathogenic copy number variation (CNV), including 14 cases of X chromosome microdeletion/microduplication; 7(19.4%) with benign CNV, and 14(38.9%) with CNV of unknown clinical significance. The fragment size [ M (min-max)] of the 15 pathogenic CNV was 1.68 Mb(0.37-9.20 Mb). Of the nine cases with microdeletions, seven were found with deletion in the Xp22.31 region. Conclusions:Numerical abnormalities are the most common fetal sex chromosome abnormalities detected from amniotic fluid samples. Others included mosaicism and chromosome structure abnormalities.
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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.
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OBJECTIVE@#To explore the genetic basis for a patient with premature ovarian insufficiency.@*METHODS@#Chromosomal G-banding and C-banding, single nucleotide polymorphism array (SNP-array), fluorescence in situ hybridization (FISH) and Y chromosome microdeletion assay were used for the analysis.@*RESULTS@#With the combined techniques, the patient was found to carry a Xq;Yq translocation, with a karyotype of 46,X,der(X)t(X;Y)(q25;q12).ish der(X)(Tel XYp+,Tel XYq+,Yq12+).@*CONCLUSION@#Unbalanced Xq;Yq translocation probably underlay the premature ovarian insufficiency in this patient.
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OBJECTIVE@#To carry out prenatal diagnosis for a fetus with high risk predicted by non-invasive prenatal testing (NIPT).@*METHODS@#Next-generation sequencing (NGS) was used to analyze free fetal DNA (ffDNA) in the maternal plasma. Chromosomal karyotyping and single nucleotide polymorphism array (SNP-array) were used to ascertain copy number variation in the fetus and its parents.@*RESULTS@#SNP-array analysis and chromosomal karyotyping revealed that the fetus had a 15.018 Mb duplication at 4q34.1q35.2 and a 7.678 Mb duplication at 21q11.2q21.1, which were derived from a t(4;21)(q34.1;q21.1) translocation carried by its mother.@*CONCLUSION@#NIPT is capable of detecting submicroscopic chromosomal abnormalities of the fetus. Combined use of genetic techniques, in particular SNP-array, is crucial for the diagnosis of partial trisomy 21q in this case.
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OBJECTIVE@#To explore the genetic etiology of a pedigree with mental retardation and hypotonia by using chromosome microarray analysis (CMA), low coverage massive parallel copy number variation sequencing (CNV-seq) and quantitative PCR (qPCR).@*METHODS@#Genomic DNA was extracted from peripheral blood samples from two male patients and healthy members from the pedigree. CNV-seq was carried out for one patient. Suspected CNV was verified by qPCR. CNV-seq or single nucleotide polymorphism array (SNP array) were carried out for another patient and his family members.@*RESULTS@#Both patients showed severe hypotonia and global development delay, in particular language delay. CNV-seq and SNP array indicated that both patients had carried a Xq28 duplication, with spanned 0.26 Mb and 0.42 Mb, respectively. Both duplications encompassed the MECP2 gene. CNV-seq analysis of their family members confirmed that the mother and one sister had carried similar duplications, while an elder brother was normal.@*CONCLUSION@#CNV-seq and CMA are rapid and effective tools for the diagnosis of MECP2 duplication syndrome in children with mental retardation, hypotonia and recurrent infections.
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OBJECTIVE@#To explore the genetic basis of a child featuring intellectual disability, developmental delay and epilepsy.@*METHODS@#Cytogenetic and molecular analysis including chromosomal karyotyping analysis, single nucleotide polymorphism array (SNP array) and qPCR were performed.@*RESULTS@#The karyotype of the child was determined as 46, XX; SNP array: arr [19]21q22.12q22.13(36 860 195-38 801 482)×1 dn. A heterozygous 1.9 Mb microdeletion was detected at 21q22.12q22.13. qPCR has confirmed deletion of exon 1 of the DYRK1A gene, which has occurred de novo.@*CONCLUSION@#A 21q22 deletion was diagnosed with multiple genetic methods. Genotype-phenotype correlation suggested DYRK1A to be a candidate for intellectual disability.
Subject(s)
Child , Humans , Developmental Disabilities , Genetics , Epilepsy , Genetics , Genetic Association Studies , Intellectual Disability , Genetics , Karyotyping , Protein Serine-Threonine Kinases , Genetics , Protein-Tyrosine Kinases , Genetics , Sequence DeletionABSTRACT
OBJECTIVE@#To explore the prenatal screening and diagnosis for a pair of monochorionic-diamniotic (MCDA) twins discordant for 45,X/46,XX mosaicism.@*METHODS@#Amniotic fluid samples were taken from both twins for whom non-invasive prenatal testing has signaled a high risk for sex chromosomal abnormality. Uncultured amniotic fluid was analyzed by fluorescence in situ hybridization (FISH) and single nucleotide polymorphism array (SNP-array). Conventional G-banded karyotyping analysis was performed on the cultured amniotic fluid.@*RESULTS@#Metaphase chromosome analysis showed that one of the twins had a mos 45,X[11]/46,XX[26] karyotype, while the other had a normal karyotype. FISH and SNP-array applied on uncultured amniotic fluid revealed about 30% mosaicism in one of the twins. The twins were confirmed to be monozygotic by SNP-array analysis.@*CONCLUSION@#To avoid confusion arising from discordant karyotypes in MCDA twins with abnormal non-invasive prenatal testing (NIPT) results, dual amniocentesis should be carried out to obtain amniotic fluid samples for chromosomal as well as molecular analysis. To determine the ratio of 45,X and 46,XX cells in Turner syndrome can provide valuable information for prenatal genetic counseling.
Subject(s)
Female , Humans , Pregnancy , Amniocentesis , Chromosomes, Human, X , In Situ Hybridization, Fluorescence , Karyotyping , Mosaicism , Prenatal DiagnosisABSTRACT
<p><b>OBJECTIVE</b>To investigate the phenotype-genotype association of isodicentromere Y chromosome by analysis of two female patients carrying the chromosome with sexual development disorders.</p><p><b>METHODS</b>The karyotypes of the two patients were determined by application of conventional G banding of peripheral blood samples and fluorescence in situ hybridization (FISH). PCR was applied to detect the presence of SRY gene.</p><p><b>RESULTS</b>Conventional karyotype analysis showed case 1 to be a mosaic: mos.45,X[38]/46,X,+mar[151]/47,XY,+mar[5]/47,X,+mar × 2[2]/46,XY[4], FISH showed that 12 different cell lines were presented in the karyotype of case 1 and partial cell lines with SRY gene, the marker is an isodicentromere Y chromosome [idic(Y)(p)]. No mutation was found in the SRY gene. The karyotype of case 2 was mos.45,X[25]/46,X,+mar[35]. FISH showed the marker to be an idic(Y)(p) without the SRY gene.</p><p><b>CONCLUSION</b>The karyotype of patients carrying idic(Y)(p) seems unstable, and female patients have the characteristics of short stature and secondary sexual hypoplasia. Karyotype analysis combined with FISH analysis can accurately determine the breakpoint of idic(Y) and identify the types of complex mosaic, which may facilitate genetic counseling and prognosis.</p>
Subject(s)
Adolescent , Child , Female , Humans , Chromosomes, Human, Y , Disorders of Sex Development , Genetics , Karyotype , Sex Chromosome Aberrations , Sex-Determining Region Y Protein , GeneticsABSTRACT
<p><b>OBJECTIVE</b>To assess the association of PEX10 gene and 1p36 copy number variations in 1p36 region with concurrent epilepsy through analyzing 3 cases.</p><p><b>METHODS</b>The karyotypes of 3 patients were determined by high resolution chromosome banding, multiplex ligation dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH) combined with single nucleotide polymorphism array (SNP) technology. Real-time PCR was carried out to determine the mRNA levels of PEX10 gene in peripheral blood of the patients.</p><p><b>RESULTS</b>No abnormality was found upon high resolution karyotyping. MLPA analysis showed that all of the 3 patients had a copy number variation of subtelomeric region in the short arm of chromosome 1, which was confirmed by FISH and SNP chip analyses. Case 1 and case 2 both had an epilepsy phenotype, and their copy number variations have encompassed the PEX10 gene. On the other hand, case 3 has absent epilepsy, and its PEX10 gene copy number was normal. Family investigation confirmed that the chromosome abnormalities in all of the 3 cases were of de novo type. Compared with healthy controls, real-time PCR showed that mRNA of the PEX10 gene was increased in case 1 but decreased in case 2.</p><p><b>CONCLUSION</b>The abnormal expression of PEX10 gene resulting from copy number variations of 1p36 region may be associated with the epilepsy phenotype.</p>