Genetic analysis of 387 cases of fetal sex chromosome abnormalities detected from amniotic fluid samples / 中华围产医学杂志

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.

Genetic analysis of a pedigree with MECP duplication syndrome / 中华医学遗传学杂志

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.

Genetic etiology analysis of 420 children with neurodevelopmental disorders / 中华实用儿科临床杂志

Objective@#To investigate the genetic etiology of neurodevelopmental disorders (NDD), and to provide a theoretical basis for its genetic counseling, family risk evaluation and prenatal diagnosis.@*Methods@#Karyotype analysis and chromosome microarray analysis (CMA) were conducted of the data from 420 children diagnosed accor-ding to NDD diagnostic criteria at Maternal and Child Health Hospital of Hunan Province from January 2016 to December 2018.@*Results@#Among the 420 cases, 14 cases (3.33%, 14/420 cases) with global developmental disabilities/intellectual disabilities (GDD/ID) had chromosomal abnormalities.The location of chromosome breakpoints and the range of deleted or duplicated fragments in 13 cases were further determined by using CMA.In this study, pathogenic copy number variations (CNVs) were detected in 61 children (14.52%, 61/420 cases), which included 31 cases (50.82%, 31/61 cases) of known syndromes, including Angelman/Prader-Will syndrome (8 cases), Williams syndrome (3 cases), Phelan-McDermid syndrome (3 cases) and other 13 syndromes, and 30 cases with clinically significant pathogenic CNVs.Additionally, by the combination of CMA and fluorescence in situ hybridization (FISH), a family were diagnosed with mental retardation caused by 10q26 and 12p13 occult rearrangement.@*Conclusions@#Chromosomal abnormalities and genomic microdeletion/duplication are the primary genetic causes for children with NDD.Combination of karyotype analysis, CMA and FISH can provide definite etiological diagnosis for these children, which has important clinical signi-ficance for the treatment of children and guidance of their parents′ reproduction.

Genetic analysis of a child with mental retardation and hypospadia / 中华医学遗传学杂志

Objective@#To carry out genetic testing for a boy presenting with mental retardation and hypoplasia.@*Methods@#Conventional karyotyping, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism based array (SNP-array) were used to analyze the boy and his parents.@*Results@#SNP-array has detected a 25.7 Mb microduplication at 2q33.3q36.3 in the boy. Chromosomal karyotyping and FISH analysis indicated that his mother had a karyotype of 46, XX, ish ins(11; 2)(p15; q33q36), and that the boy has carried an abnormal chromosome 11 derived from the maternal translocation. The karyotype of the boy was ascertained as 46, XY, ish der(11)ins(11; 2)(p15; q33q36)mat.@*Conclusion@#SNP-array combined with G-banding and FISH can delineate the cryptic translocation and is valuable for the assessment of recurrence risk for subsequent pregnancies.

Genetic analysis of a child with mental retardation and hypospadia / 中华医学遗传学杂志

OBJECTIVE@#To carry out genetic testing for a boy presenting with mental retardation and hypoplasia.@*METHODS@#Conventional karyotyping, fluorescence in situ hybridization (FISH) and single nucleotide polymorphism based array (SNP-array) were used to analyze the boy and his parents.@*RESULTS@#SNP-array has detected a 25.7 Mb microduplication at 2q33.3q36.3 in the boy. Chromosomal karyotyping and FISH analysis indicated that his mother had a karyotype of 46,XX,ish ins(11;2) (p15;q33q36), and that the boy has carried an abnormal chromosome 11 derived from the maternal translocation. The karyotype of the boy was ascertained as 46,XY,ish der(11)ins(11;2) (p15;q33q36)mat.@*CONCLUSION@#SNP-array combined with G-banding and FISH can delineate the cryptic translocation and is valuable for the assessment of recurrence risk for subsequent pregnancies.

Identification of a de novo interstitial 21q22.12q22.13 deletion in a patient with intellectual disability / 中华医学遗传学杂志

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.

Prenatal diagnosis of monochorionic-diamniotic twins discordant for 45,X/46,XX mosaicism / 中华医学遗传学杂志

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.

Establishment of hemophilia A patient-specific inducible pluripotent stem cells with urine cells / 中华医学遗传学杂志

OBJECTIVE To generate hemophilia A (HA) patient-specific inducible pluripotent stem cells (iPSCs) and induce endothelial differentiation. METHODS Tubular epithelial cells were isolated and cultured from the urine of HA patients. The iPSCs were generated by forced expression of Yamanaka factors (Oct4, Sox2, c-Myc and Klf4) using retroviruses and characterized by cell morphology, pluripotent marker staining and in vivo differentiation through teratoma formation. Induced endothelial differentiation of the iPSCs was achieved with the OP9 cell co-culture method. RESULTS Patient-specific iPSCs were generated from urine cells of the HA patients, which could be identified by cell morphology, pluripotent stem cell surface marker staining and in vivo differentiation of three germ layers. The teratoma experiment has confirmed that such cells could differentiate into endothelial cells expressing the endothelial-specific markers CD144, CD31 and vWF. CONCLUSION HA patient-specific iPSCs could be generated from urine cells and can differentiate into endothelial cells. This has provided a new HA disease modeling approach and may serve as an applicable autologous cell source for gene correction and cell therapy studies for HA.