Consensus on laboratory diagnosis of congenital adrenal hyperplasia due to 21 hydroxylase deficiency / 中华医学遗传学杂志

21 hydroxylase deficiency (21-OHD), the most common form of congenital adrenal hyperplasia, is caused by defects in CYP21A2 gene, which encodes the cytochrome P450 oxidase (P450C21) involved in glucocorticoid and mineralocorticoid synthesis. The diagnosis of 21-OHD is based on the comprehensive evaluation of clinical manifestation, biochemical alteration and molecular genetics results. Due to the complex structure of CYP21A2, special techniques are required to perform delicate analysis to avoid the interference of its pseudogene. Recently, the state-of-the-art diagnostic methods were applied to the clinic gradually, including the steroid hormone profiling and third generation sequencing. To standardize the laboratory diagnosis of 21-OHD, this consensus was drafted on the basis of the extensive knowledge, the updated progress and the published consensuses and guidelines worldwide by expert discussion organized by Rare Diseases Group of Pediatric Branch of Chinese Medical Association, Medical Genetics Branch of Chinese Medical Doctor Association, Birth Defect Prevention and Molecular Genetics Branch of China Maternal and Child Health Association. and Molecular Diagnosis Branch of Shanghai Medical Association.

Expert consensus on the detection of genome-wide copy number variations in abortive tissues and family reproductive consultation / 中华医学遗传学杂志

Chromosomal aberrations including numerical abnormalities and segment duplications/deletions, as genome-wide copy number variations (CNVs), are a leading cause for spontaneous abortion. Analysis of abortive tissues for such CNVs can detect potential genomic variations in the couple and provide guidance for the choice of appropriate method to avoid further miscarriage or birth of child with chromosomal disorders. With evidence-based clinical data, an expert group jointly formed by the Genetic Disease Prevention and Control Group, Committee for Birth Defects Prevention and Control, Chinese Association of Preventive Medicine; the Clinical Genetics Group, the Society of Medical Genetics, Chinese Medical Association; the Professional Committee for Prenatal Diagnosis of Genetic Diseases, the Society of Medical Geneticists, Chinese Medical Doctor Association has discussed and formulated this consensus, with an aim to provide guidance for the application of genomic CNVs detection for the abortive tissue and genetic counseling for family reproduction.

Genetic analysis of a gonadal-mosaicism BMD family with prenatal diagnosis and PGT-M / 中华检验医学杂志

Objective:To identify the pathogenic characteristics of a suspected gonadal mosaicism Becker muscular dystrophy (BMD) family, and provide provide basis for pregnancy selection of similar families.Methods:A BMD family admitted to Hunan Jiahui Genetics Hospital from June 2012 to September 2019 was systematically reviewed. The medical history and family history of the proband were checked, and multiplex ligation-dependent probe amplification was used to detect the deletion/duplication of 79 exons of the Duchenne muscular dystrophy (DMD) gene in the proband, fetuses, and parents. Moreover, potential variants were verified by combining PCR amplification, short tandom repeat polymorphic linkage analysis, and real-time fluorescence quantitative PCR. High-quality embryos are screened for transplantation after preimplantation genetic testing for monogenic (PGT-M). And amniotic fluid was collected in the second trimester for prenatal diagnostic verification.Results:According to the phenotype analysis of the proband, the initial clinical diagnosis was BMD, and the exon 45-50 deletion in DMD gene was detected. The mutation was not detected in the mother′s peripheral blood, but when she was pregnant again, the prenatal diagnosis showed that the fetus had the same deletion mutation as the proband. Neither of two vitro embryos tested by PGT-M has the deletion mutation, then single embryo transfer was performed nor was pregnancy successful. After confirmation of prenatal diagnosis during pregnancy, a normal baby girl was born by full-term cesarean section.Conclusions:This BMD family was a family with two consecutive BMD homodeletion mutations, and the mutation of the DMD gene was not detected in the peripheral blood of the proband′s mother and two embryonic cells, suggesting that the mother may be a gonad chimeric carrier of this deletion mutation. The combined application of prenatal diagnosis and PGT-M provides a reference approach to effectively avoid the birth of similar children.

Detection of Spinal Muscular Atrophy Using a Duplexed Real-Time PCR Approach With Locked Nucleic Acid-Modified Primers

Background@#Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder mainly caused by homozygous deletions that include exon 7 of the survival motor neuron 1 (SMN1) gene. A nearby paralog gene, SMN2, obstructs the specific detection of SMN1. We optimized a duplexed real-time PCR approach using locked nucleic acid (LNA)-modified primers to specifically detect SMN1. @*Methods@#An LNA-modified primer pair with 3´ ends targeting SMN1 specific sites c.835-44g and c.840C was designed, and its specificity was examined by real-time PCR and Sanger Sequencing. A duplexed real-time PCR approach for amplifying SMN1 and control gene albumin (ALB) was developed. A randomized double-blind trial with 97 fresh peripheral blood samples and 25 dried blood spots (DBS) was conducted to evaluate the clinical efficacy of the duplexed approach. This new approach was then used to screen 753 newborn DBS. @*Results@#The LNA-modified primers exhibited enhanced specificity and 6.8% increased efficiency for SMN1 amplification, compared with conventional primers. After stabilizing the SMN1 test by optimizing the duplexed real-time PCR approach, a clinical trial validated that the sensitivity and specificity of our new approach for detecting SMA patients and carriers was 100%. Using this new approach, 15 of the screened 753 newborns were identified as carriers via DBS, while the rest were identified as normal individuals. These data reveal a carrier rate of 1.99% in Hunan province, South Central China. @*Conclusions@#We have developed a novel, specific SMN1 detection approach utilizing real-time PCR with LNA-modified primers, which could be applied to both prenatal carrier and newborn screening.

Biochemical and genetic characteristics of 40 neonates with carnitine deficiency / 中南大学学报(医学版)

OBJECTIVES@#Primary carnitine deficiency (PCD) is a rare fatty acid metabolism disorder that can cause neonatal death. This study aims to analyze carnitine levels and detect SLC22A5 gene in newborns with carnitine deficiency, to provide a basis for early diagnosis of PCD, and to explore the relationship between carnitine in blood and SLC22A5 genotype.@*METHODS@#A total of 40 neonates with low free carnitine (C0G (p.Y251C), c.495 C>A (p.R165E), and c.1298T>C (p.M433T). We found 14 PCD patients including 2 homozygous mutations and 12 heterozygous mutations, 14 with 1 mutation, and 12 with no mutation among 40 children. The C0 concentration of children with SLC22A5 gene homozygous or complex heterozygous mutations was (4.95±1.62) μmol/L in the initial screening, and (3.90±1.33) μmol/L in the second screening. The C0 concentration of children with no mutation was (7.04±2.05) μmol/L in the initial screening, and (8.02±2.87) μmol/L in the second screening. There were significant differences between children with homozygous or compound heterozygous mutations and with no mutation in C0 concentration of the initial and the second screening (both @*CONCLUSIONS@#There are 5 new mutations which enriched the mutation spectrum of SLC22A5 gene. C0<5 μmol/L is highly correlated with SLC22A5 gene homozygous or compound heterozygous mutations. Children with truncated mutation may have lower C0 concentration than that with untruncated mutation in the initial screening.

Prenatal diagnosis for 30 women carrying a FMR1 mutation / 中华医学遗传学杂志

Objective@#To determine the CGG repeat number and methylation status of FMR1 gene for fetuses whose mothers have carried a FMR1 mutation.@*Methods@#For 30 pregnant women, the fetal CGG repeat number was determined with a GC-rich PCR system by using chorionic villus, amniotic fluid or umbilical blood samples. The methylation status of the FMR1 gene was confirmed with Southern blotting.@*Results@#In total 30 prenatal diagnoses were performed for 29 carriers of FMR1 gene mutations and 1 with FMR1 gene deletion mosaicism. Three fetuses were found to carry premutations, 9 were with full mutations and 1 with mosaicism of premutation and full mutations. Eighteen fetuses were normal.@*Conclusion@#Considering the genetic complexity of Fragile X syndrome (FXS), single method may not suffice accurate determination of their genetic status. The pitfalls and technical limitations of protocols requires adoption of personalized strategy for its prenatal diagnosis.

A case of Antley-Bixler syndrome caused by novel POR mutations / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a child affected with multiple malformations.@*Methods@#Genomic DNA was extracted from peripheral blood samples from the child and her parents. Tro whole exome sequencing and bioinformatics analysis were carried out. Suspicted mutations were verified by PCR and Sanger sequencing.@*Results@#The patient, a 2-year-old girl, presented with multiple malformations including dysmorphism, skeletal malformations and ambigulous genitalia. Through genetic testing, she was diagnosed with Antley-Bixler syndrome caused by compound heterozygous mutations of the POR gene (c.919G>T and c. 1615G>A), which were derived from her mother and father, respectively.@*Conclusion@#The compound heterozygous mutations of the POR gene probably underlie the Antley-Bixler syndrome in this patient.

Genetic diagnosis and noninvasive prenatal testing of a family with Williams-Beuren syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis of a fetus with ventricular septal defect (VSD) by using modified noninvasive prenatal testing (NIPT) for the detection of microdeletion syndromes.@*METHODS@#Chromosomal karyotypes of the fetus and its parents were analyzed by G-banding technique. Next generation sequencing (NGS) was used to detect genomic copy number variations (CNVs) in cell-free fetal DNA. The results were verified by fluorescence in situ hybridization (FISH).@*RESULTS@#The fetus and its parents all had a normal karyotype at 320-400 band level. NGS revealed a deletion of 1.30 Mb at 7q11.23 in the fetus, with a 93% overlap with that of Williams-Beuren syndrome (WBS). The father also had a deletion of 1.42 Mb at 7q11.23, with a 99% overlap with that of WBS. Modified NIPT also detected the 1.30 Mb deletion at 7q11.23 in the fetus. The result of FISH has confirmed the above results.@*CONCLUSION@#It is necessary to carry out genetic testing on fetuses with VSD. NGS can detect fetal microdeletion syndromes and help to trace their parental origin. The modified NIPT for fetal chromosomal microdeletions/microduplication syndromes is highly accurate.

Molecular diagnosis and functional study of a pedigree affected with Lubs X-linked mental retardation syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with X-linked mental retardation.@*METHODS@#The proband was subjected to chromosomal karyotyping, FMR1 mutation testing and copy number variation analysis with a single nucleotide polymorphism microarray (SNP array). His family members were subjected to multiplex ligation-dependent probe amplification (MLPA) assaying. Expression of genes within the repeated region were analyzed.@*RESULTS@#The proband had a normal chromosomal karyotype and normal number of CGG repeats within the FMR1 gene. SNP array identified a 370 kb duplication in Xq28 (ChrX: 153 027 633-153 398 515), which encompassed 14 genes including MECP2. The patient was diagnosed as Lubs X-linked mental retardation syndrome (MRXSL). MLPA confirmed the presence of copy number variation, its co-segregation with the disease, in addition with the carrier status of females. Genes from the duplicated region showed higher levels of expression (1.79 to 5.38 folds) within peripheral blood nucleated cells of the proband.@*CONCLUSION@#The patients were diagnosed with MRXSL. The expression of affected genes was up-regulated due to the duplication. Genetic counseling and prenatal diagnosis may be provided based on the results.

Genetic diagnosis and non-invasive prenatal testing of a fetus with Prader-Willi/Angelman syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus featuring growth restriction and validate the effectiveness of a novel noninvasive prenatal testing (NIPT) technique for the detection of chromosomal microdeletions.@*METHODS@#Next-generation sequencing(NGS) and fluorescence in situ hybridization(FISH) were used to analyze the DNA of the fetus. Conventional G-banding was used to analyze the karyotypes of the fetus and its parents. High-throughput sequencing was used to analyze free fetal DNA.@*RESULTS@#NGS analysis has revealed a 4.88 Mb deletion at 15q11.2-q13.1 region in the fetus, which has a 99% overlap with the critical region of Prader-Willi syndrome (Type 2) and Angelman syndrome (Type 2) and encompassed critical genes including SNRPN and UBE3A. NIPT also revealed a 4.6 Mb deletion at 15q12, which was consistent with the results of fetal cord blood and amniotic DNA testing. FISH assay has confirmed the result of NGS. By karyotying, all subjects showed a normal karyotypes at a level of 320~400 bands.@*CONCLUSION@#It is quite necessary to carry out genetic testing on fetuses showing growth restriction. NIPT for fetal chromosomal microdeletions/microduplication syndromes is highly accurate for the diagnosis of Prader-Willi/Angelman syndrome.

Prenatal diagnosis for 30 women carrying a FMR1 mutation / 中华医学遗传学杂志

OBJECTIVE@#To determine the CGG repeat number and methylation status of FMR1 gene for fetuses whose mothers have carried a FMR1 mutation.@*METHODS@#For 30 pregnant women, the fetal CGG repeat number was determined with a GC-rich PCR system by using chorionic villus, amniotic fluid or umbilical blood samples. The methylation status of the FMR1 gene was confirmed with Southern blotting.@*RESULTS@#In total 30 prenatal diagnoses were performed for 29 carriers of FMR1 gene mutations and 1 with FMR1 gene deletion mosaicism. Three fetuses were found to carry premutations, 9 were with full mutations and 1 with mosaicism of premutation and full mutations. Eighteen fetuses were normal.@*CONCLUSION@#Considering the genetic complexity of Fragile X syndrome (FXS), single method may not suffice accurate determination of their genetic status. The pitfalls and technical limitations of protocols requires adoption of personalized strategy for its prenatal diagnosis.

A case of Antley-Bixler syndrome caused by novel POR mutations / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a child affected with multiple malformations.@*METHODS@#Genomic DNA was extracted from peripheral blood samples from the child and her parents. Tro whole exome sequencing and bioinformatics analysis were carried out. Suspicted mutations were verified by PCR and Sanger sequencing.@*RESULTS@#The patient, a 2-year-old girl, presented with multiple malformations including dysmorphism, skeletal malformations and ambigulous genitalia. Through genetic testing, she was diagnosed with Antley-Bixler syndrome caused by compound heterozygous mutations of the POR gene (c.919G>T and c.1615G>A), which were derived from her mother and father, respectively.@*CONCLUSION@#The compound heterozygous mutations of the POR gene probably underlie the Antley-Bixler syndrome in this patient.

The application of next generation sequencing on non-invasive prenatal testing: today and tomorrow / 中华检验医学杂志

Next-generation sequencing has boosted the development and application of non-invasive prenatal testing.Non-invasive prenatal screening of fetal aneuploidies (T21/T18/T13) has been widely applied around the world as the well-recognized best screening method because of its high sensitivity, low false-positive rate and false-negative rate.Non-invasive prenatal testing of fetal sex chromosome aneuploidies, common chromosome deletion-duplication syndromes and several monogenic disorders has also become technically feasible.It can be expected that primary challenges in the future would be the issues of clinical services and proper managements.

Application of single nucleotide polymorphism array for the identification of pathogenic copy number variations in fetuses with malformations and women with an adverse reproductive history / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To apply single nucleotide polymorphism microarray (SNP array) for the detection of genome-wide copy number variations(CNVs) in fetuses with malformations and women with an adverse reproductive history, and to explore the correlation of rare CNVs with the clinical manifestations.</p><p><b>METHODS</b>Amniotic fluid and umbilical cord blood samples were collected from 314 women with singleton pregnancy. SNP array was performed on samples where chromosomal abnormalities were excluded after G-banding analysis.</p><p><b>RESULTS</b>Pathological CNVs were detected in 8.91% (28/314) of all samples, which included 11 duplications, 9 deletions, 4 loss of heterozygosity (LOH), and 4 conjoined deletions and duplications. The sizes of duplications and deletions were between 0.47 Mb and 16.7 Mb, and between 0.16 Mb and 13.3 Mb, respectively. Fifteen CNVs were mapped to the regions of microdeletion or microduplication syndromes or regions associated with clinical manifestations, while the remainder 13 were considered benign or variant of uncertain significance.</p><p><b>CONCLUSION</b>A proportion of fetuses with malformations and women with an adverse reproductive history may be attributed to CNVs, half of which are mapped with to the regions of well known syndromes. SNP array may facilitate discovery of new syndromes and provide a basis for genetic counseling and prenatal diagnosis.</p>

Genetic diagnosis and analysis for two cases of ring chromosome 22 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To confirm the genetic diagnosis of two patients with ring chromosome 22 syndrome and investigate the mechanism underlying the formation of r(22) and potential genetic causes for the clinical phenotypes.</p><p><b>METHODS</b>Cytogenetic and molecular analyses using standard G-banding, fluorescence in situ hybridization and single nucleotide polymorphism array (SNP array) were performed.</p><p><b>RESULTS</b>For case 1, the karyotype was 46,XY,r(22)(p11q13). SNP array has identified a 7.0 Mb heterozygous deletion at 22q13.2q13.33. For case 2, the karyotype was 46,XY,r(22)(p11q13)[84]/45,XY,-22[6]; SNP array has detected a heterozygous microdeletion of 1.6 Mb at 22q13.33.</p><p><b>CONCLUSION</b>With combined application of genetic testing, 2 cases of r(22) syndrome were diagnosed, which has improved the understanding of the genotype-phenotype correlation of r(22).</p>

The clinical application and follow-up study of f non-invasive prenatal testing / 重庆医学

Objective To provide valid data and useful genetic counseling in the clinical application of non‐invasive prenatal test (NIPT) ,fetal chromosomal disorder were screened by massive parallel sequencing and made a follow‐up study .Methods Preg‐nant women with Down screening in high‐risk were screened by NIPT ;NIPT verified high‐risk individuals were suggested for kary‐otyping ;and we follow up on whoever showed low risk by NIPT before and after their deliveries .Results (1)Totally 1 676 cases of pregnant women were tested by NIPT ,25 cases prompted to be abnormal ,with an abnormal rate of 1 .49% ,karyotype analysis re‐sults in 12 cases of abnormalit ,the accuracies of NIPT for T21 ,T18 ,XO ,XXY ,and XYY were 99 .93% ,100 .00% ,99 .66% , 100 .00% ,100 .00% respectively ;the accuracy of NIPT for women with advanced paternal age and twins were both 100 .00% ;kary‐otyping positive individuals underwent abortion ,which gives a prenatal intervention rate of 100 .00% .(2)Out of 1 651 cases of NIPT low risk testers ,1 468 cases were successfully followed up ,with a 88 .91% success rate .We found chromosome abnormality with one case of inversion of chromosome 9 (maternal) .(3)Ultrasound‐detection possessed 98 .17% accuracy and 7 .69% in detec‐tion rate;in high‐risk pregnant woman ,Down screening had an accuracy of 0 .88% and false positive rate of 99 .12% ;98 .71%women were avoided prenatal diagnosis via NIPT .Conclusion Compare to ultrasound and maternal plasma screening ,NIPT is a far more accurate prenatal screening approach .To build effective follow‐up and service systems of NIPT is necessary to reduce birth de‐fects in medical institutions .

Analysis of CGG repeat instability in germline cells from two male fetuses affected with fragile X syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the pattern of CGG repeat instability within germline cells derived from two male fetuses affected with Fragile X syndrome (FXS).</p><p><b>METHODS</b>The length and methylation status of CGG repeats within the testes of a fetus carrying a full FXS mutation and another fetus carrying mosaicism FXS mutation were analyzed with Southern blotting and AmplideX FMR1 PCR. Immunohistochemistry was also applied for the measurement of FMR1 protein (FMRP) expression within the testes.</p><p><b>RESULTS</b>For the fetus carrying the full mutation, Southern blotting analysis of the PCR product has detected an expected band representing the full mutation in its brain and a premutation band of > 160 CGG repeats in its testis. Whereas the pattern of premutation/full mutation in mosaic testis was similar to that in peripheral blood and no sign of contracted fragment was found other than a band of about 160 CGG repeats. Immunohistochemistry assay with a FMRP-specific antibody demonstrated a number of FMRP-positive germ cells, which suggested a contraction from full mutation to premutation alleles.</p><p><b>CONCLUSION</b>This study has clarified the instability pattern of CGG repeat and expression of FMRP protein within the testes of fetuses affected with FXS, confirming that the CGG repeat can contract progressively within the germline. The FMRP expression in the testis is consistent with spermatogonium proliferation, and thus the contraction from full mutation to unmethylated premutations may occur for the requirement of FMRP expression during spermatogenesis. The better understanding of FMRP function during germ cell proliferation may elucidate the mechanism underlying the contraction of full FXS mutation in male germline.</p>

Influence of chromosomal polymorphisms on the clinical outcome of patients undergoing in vitro fertilization embryo transfer / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the influence of chromosome polymorphisms on the outcome of in vitro fertilization embryo transfer (IVF-ET).</p><p><b>METHODS</b>Patients who completed the first cycle of in vitro fertilization fresh embryo transfer were retrospective studied. Patients with the chromosome polymorphisms were classified as to the study group (200 treatment cycles), all patients with normal chromosomes at the same period were classified as the control group (4777 treatment cycles).</p><p><b>RESULTS</b>No significant difference was found between the chromosome polymorphisms and the control groups in terms of clinical pregnancy rate (44.50% vs. 39.85%, P=0.750), early abortion rate (15.73% vs. 10.79%, P=0.163) and live birth rate per cycle (34.5% vs. 30.73%, P=0.437) except for fertilization rate (60.94% vs. 64.08%, P=0.001), cleavage rate (95.01% vs. 97.09%, P=0.000) and good quality embryo rate (53.8% vs. 58.2%, P=0.001).</p><p><b>CONCLUSION</b>Chromosomal polymorphisms appeared to have no adverse influence on the outcome of IVF-ET treatment.</p>

Prenatal diagnosis of a case of Pallister-Killian syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the clinical and genetic characteristics of Pallister-Killian syndrome and improve the diagnosis for this rare chromosomal disease.</p><p><b>METHODS</b>Standard G-banding was carried out for the patient and his parents. Single nucleotide polymorphism array (SNP array) for copy number detection was applied to identify chromosome microdeletion or microduplication. Interphase fluorescence in situ hybridization (FISH) and cytogenetic analyses of fibroblast cells were performed based on the Results of array.</p><p><b>RESULTS</b>The patient's G-banded karyotype has turned out to be 46,XY, whilst his parents were both normal. A duplication of the whole short arm of chromosome 12 was detected by SNP array in the child. The result of interphase FISH performed on interphase chromosomes derived from peripheral blood cells was nucish (RP11-104 b5, a19 RP11-956) × 4 [19/100］, whilst the karyotype of fibroblast cells was 47,XY,+i(12) (p10 [44]/46, XY[56].</p><p><b>CONCLUSION</b>By combining with clinical characteristics, SNP array, skin fibroblasts karyotype analysis and FISH can diagnose Pallister-Killian syndrome effectively.</p>

Application of next-generation DNA sequencing for prenatal testing of fetal chromosomal aneuploidies / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the value of next-generation sequencing for the non-invasive prenatal testing of fetal chromosomal aneuploidies.</p><p><b>METHODS</b>Plasma from 4004 women with singleton pregnancy at a gestational age between 12-35(+5) weeks was collected prior to amniocentesis between April 19th 2011 and December 31st 2013. The samples were divided into three groups: (1) High risk for Down syndrome by biochemical screening; (2) Advanced maternal age; (3) Abnormalities by ultrasound or other methods. Plasma DNA extracted from above samples was sequenced at low coverage. Positive results were verified against the karyotypes of the fetuses. For those with negative results, the fetuses were followed up by telephone call for at least six months after birth.</p><p><b>RESULTS</b>Among 4003 samples subjected to non-invasive prenatal diagnosis, 66 (1.65%) had a positive result. In group 1, 22 cases of trisomy 21 (T21), 3 cases of trisomy 18 (T18), 1 case of 13 trisomy (T13), 8 cases of 45,X and 2 cases of other chromosomal abnormality were detected. In group 2, 13 cases of T21, 2 cases of T18, 1 case of T13, 5 cases of 45,X, 2 cases of 47,XXN and 1 case of other chromosomal abnormality were detected. In group 3, 1 case of T21, 1 case of T18, 1 case of T13, and 3 cases of 47,XXN were detected. For 55 samples underwent prenatal diagnosis, 30 cases of T21 and 4 cases of T18 were discovered, which was consistent with the results of non-invasive prenatal diagnosis. For the 13 cases indicated as 45,X, 3 were verified by karyotype analysis, 2 were verified as mosaicism (45,X/46,XN), 8 were 46,XN (false positives). For the 5 cases indicated as 47,XXN, 2 were verified by karyotype analysis, the other 3 were 46,XN (false positives). Karyotypes of 3 cases suspected for other chromosomal abnormalities were all verified as 46,XN (false positive). Until May 1st 2014, telephone follow-up for those with negative screening results only identified a boy with facial abnormalities and developmental delay, which was similar to his older sister, combined karyotyping and fluorescence in situ hybridization analysis has verified the karyotype of the boy as 46,XY,rec(14)dup(14q)inv(14)(p12q14)pat.</p><p><b>CONCLUSION</b>Our results indicated that sequencing of plasma free DNA can rapidly detect fetal chromosomal aneuploidies. The method is non-invasive, and the results are highly consistent with karyotype analysis in terms of accuracy and specificity. Non-invasive testing can be used as an effective adjunct to conventional prenatal diagnostic methods, which can greatly reduce unnecessary invasive prenatal diagnosis. However, the sensitivity and accuracy for aneuploidy detection other than chromosome 13/18/21 still need to be improved.</p>