Detección rápida de aneuploidías para la definición de incompatibilidad con la vida extrauterina independiente / Rapid detection of aneuploidies for definition of incompatibility with independent extrauterine life

OBJETIVO: Analizar la implementación de la prueba rápida de reacción en cadena de la polimerasa cuantitativa y fluorescente (QF-PCR) para la detección de aneuploidías. MÉTODO: Se incluyeron todas las pacientes que se realizaron una QF-PCR entre septiembre de 2017 y mayo de 2021. En todos los casos se consignaron los datos clínicos, ecográficos y de laboratorio, y se efectuó un seguimiento de quienes se realizaron además cariograma y su resultado fue normal. RESULTADOS: Se realizaron 213 procedimientos invasivos genéticos prenatales, siendo 72 para detección rápida de aneuploidía mediante QF-PCR. El promedio de edad de las madres con QF-PCR fue de 37 años y 48 pacientes (67%) tenían menos de 15 semanas de gestación. La QF-PCR demostró aneuploidía de los cromosomas 18, 13 y de triploidía en 21 de 49 casos informados como anormales. De los 22 casos sin sugerencia de alteración, 17 accedieron a proseguir el estudio con cariotipo, que resultó anormal en 6 casos. Hubo 4 casos de discordancia entre la QF-PCR y el cariotipo, que pudo afectar el manejo clínico de la gestación. En 25/72 casos (34,7%) la aneuploidía era letal. CONCLUSIONES: Considerando la necesidad de tener un diagnóstico rápido, pero también completo y que permita un consejo genético apropiado, debería integrarse la QF-PCR a un protocolo de diagnóstico que considere variables clínicas y ecográficas.

OBJECTIVE: To analyze the performance of QF-PCR test for the detection of aneuploidies. METHOD: All patients who underwent QF-PCR from September 2017 to May 2021, were included. Clinical, ultrasound and laboratory data were recorded in all cases, as well as follow-up of the cases, including those performing karyotype and the result was normal. RESULTS: 213 prenatal genetic invasive procedures were performed in the study period, 72 for rapid detection of aneuploidy by QF-PCR. 48 patients (67%) were less than 15 weeks at the time of ultrasound diagnosis. The QF-PCR test demonstrated aneuploidy of chromosomes 18, 13, and triploidy in 21/49 cases reported as abnormal. Of the cases without suggestion of alteration (22), 17 agreed to continue the study with a karyotype, which was abnormal in 6 cases. There were 4 cases of discrepancy between QF-PCR and karyotype, which could affect the clinical management of pregnancy. 25/72 cases (34. 7%) corresponded to lethal aneuploidy. CONCLUSIONS: Our results justify the use of QF-PCR. Considering the need to have a rapid diagnosis, but also complete and that allows appropriate genetic counseling, it is that QF-PCR should be integrated into a protocol that considers clinical and ultrasound variables.

Molecular studies on parental origin and cell stage of nondisjunction in sex chromosome aneuploidies / 中华预防医学杂志

To study the parental origin and cell stage of nondisjunction in sex chromosome aneuploidies. Retrospectiving and analyzing the results of 385 cases of SCA confirmed by QF-PCR and karyotype analysis in the prenatal diagnosis center of Guangzhou Women and Children Medical Center from January 2015 to December 2020. The types of samples and prenatal diagnosis indications were analyzed. The parental origin and cell stage of nondisjunction in sex chromosome aneuploidies analyzed by comparing the short tandem repeat (STR) peak patterns of samples from fetuses and maternal peripheral blood. The results show that (1) There were 324 cases of nonmosaic SCA, 113 cases (113/324, 34.9%) were 45, XO, 118 cases (118/324, 36.4%) were 47, XXY, 48 cases (48/324, 14.8%) were 47, XXX and 45 cases (45/324, 13.9%) were 47, XYY. 68 (45/324, 60.2%) cases of 45, X were detected in villus samples. The other SCA cases were mainly detected in amniotic fluid samples. There were 61 mosaic SCA samples, 58(58/61, 95.1%) of mosaic SCA samples were mosaic 45, X. (2) The top two indications of 45, X cases are increased nuchal translucency(53/113, 46.9%) and fetal cystic hygroma (41/113, 36.3%), while the most common indication of other types of SCA was high risk of NIPT(170/272, 62.5%). (3) Among 45, X cases, there were 88 cases (88/113, 77.9%) inherit their single X chromosome from their mother and 25 cases (25/119, 22.1%) from their father. In 47, XXY samples, 47 cases (47/118, 39.8%) of chromosome nondisjunction occurred in meiosis stage Ⅰ of oocytes, 51 cases (51/118, 43.2%) occurred in meiosis stage Ⅰ of spermatocytes, and 20 cases (20/118, 16.9%) occurred in meiosis stage Ⅱ of oocytes. Among 47, XXX samples, 29 cases (29/48, 60.4%) of X chromosome nondisjunction occurred in meiosis stage Ⅰof oocytes, 15 cases (15/48, 31.3%) occurred in meiosis stage Ⅱ of oocytes, and 4 cases (4/48, 8.3%) occurred in meiosis stage Ⅱ of spermatocytes. In summary , the cases of 45, X were mainly diagnosed by villous samples for abnormal ultrasound findings. The other cases of SCA were mainly diagnosed by amniocentesis samples for abnormal NIPT results. Different types of SCA, the origin and occurrence period of sex chromosome nondisjunction were different.

Application of genomic copy number variation detection technology in prenatal diagnosis of 7617 pregnant women with serological screening abnormalities during the second trimester of pregnancy / 中华医学遗传学杂志

OBJECTIVE@#To analyze the genomic variation characteristics of fetal with abnormal serological screening, and to further explore the value of copy number variation (CNV) detection technology in prenatal diagnosis of fetal with abnormal serological screening.@*METHODS@#7617 singleton pregnant women who underwent amniocentesis for prenatal diagnosis solely due to abnormal Down's serological screening were selected. According to the results of serological screening, the patients were divided into high risk group, borderline risk group and single abnormal multiple of median (MOM) group. CMA and CNV-Seq were used to detect the copy number variation of amniotic fluid cell genomic DNA and combined with amniotic fluid cell karyotype analysis for prenatal diagnosis. Outpatient revisit combined with telephone inquiry was used for postnatal follow-up.@*RESULTS@#Among 7617 amniotic fluid samples, aneuploidy was detected in 138cases (1.81%) by CMA and CNV-Seq, 9 cases of aneuploid chimerism were detected by amniotic fluid cell karyotype analysis, and 203 cases of fetus carrying pathogenic and likely pathogenic CNV (P/LP CNV) were detected, the variant of uncertain significance (VUS) was detected in 437 cases (5.7%), the overall abnormal detection rate was 10.33%. The detection rate of aneuploidy by CMA and CNV-Seq in three group were 123 cases (2.9%), 13 cases (1.3%) and 2 cases (0.4%), respectively,and showing no significant difference (χ 2=7.469, P=0.024). The detection rate of pathogenic and likely pathogenic CNV in three group were 163cases (2.6%); 24 cases (2.6%) and 16 cases (3.3%), respectively, and showing no significant difference (χ 2=0.764, P=0.682). The CMA reported 2.9% (108/3729)P/LP CNV, and CNV-seq reported 2.4% (95/3888)P/LP CNV, both tests showed similar detective capabilities (χ 2=1.504, P=0.22).The most popular P/LP CNV in this cohort were Xp22.31 microdeletion, 16p13.11 microduplication /microdeletion, 22q11.21 microduplication /microdeletion. In fetuses with P/LP CNV CNV, 59 fetuses were terminated pregnancy, and 32 of 112 fetuses born had abnormal clinical manifestations. Non-medically necessary termination of pregnancy occurred in 11 fetuses carrying VUS CNV, 322 fetuses carrying VUS CNV were born, 4 of them presented abnormal clinical manifestations.@*CONCLUSION@#Compared with the traditional chromosome karyotype, CMA and CNV-Seq can improve the detection rate of pathogenic and likely pathogenic CNV. CMA and CNV-seq can be used for first tier diagnosis of pregnant women in the general population with abnormal Down's serological screening.

Practice of clinical application of noninvasive prenatal testing based on cell-free fetal DNA / 中华医学遗传学杂志

OBJECTIVE@#To assess the application value of noninvasive prenatal testing (NIPT) based on cell-free fetal DNA.@*METHODS@#The results of 2777 cases of basic and extended NIPT were retrospectively analyzed. The clinical data and outcome of pregnancy were analyzed, in addition with the diagnosis rate and testing efficiency.@*RESULTS@#Among the 2777 pregnant women, 1192 (42.9%) had accepted basic NIPT and 1585 (57.1%) accepted extended NIPT. With a failure rate of 0.1%, 8 and 6 cases were reported respectively as high-risk pregnancies for trisomy 21 and sex chromosomal abnormalities. Other genetic abnormalities were detected in 32 cases. The positive predictive value for trisomy 21 was 85.7%, and one case of 47,XXX was diagnosed among 3 women with high risks for sex chromosomal abnormalities. For those with a high risk for other genetic abnormalities, pregnant diagnosis rates of basic and extended NIPT were 71.4% (5/7) and 68.2% (15/22), respectively. Seven copy number variations (CNVs) were confirmed, including one pathogenic CNV, one likely pathogenic CNV and 5 variants of unknown significance. Among 6 cases with high-risk of maternal CNVs, 5 fetuses and the mothers were confirmed to be carriers. No CNV was detected in the remainder fetus by chromosomal microarray analysis, while its mother was a carrier of the corresponding CNV.@*CONCLUSION@#NIPT has shown a relatively high positive predictive value for the screening of trisomy 21 and maternal CNVs but with a limited efficiency for the discovery of fetal CNVs. For other genetic abnormalities signaled by NIPT, informed choice by the pregnant women during pre-testing consultation is recommended. Invasive prenatal diagnosis should be considered in the combination of NIPT reports and fetal ultrasound, while the residual risks should be fully informed.

Retrospective and cost-effective analysis of the result of Changsha Municipal Public Welfare Program by Noninvasive Prenatal Testing / 中华医学遗传学杂志

OBJECTIVE@#To assess the practical and health economical values of non-invasive prenatal test (NIPT) in Changsha Municipal Public Welfare Program.@*METHODS@#A retrospective analysis was carried out on 149 165 women undergoing NIPT test from April 9, 2018 to December 31, 2019. For pregnant women with high risks, invasive prenatal diagnosis and follow-up of pregnancy outcome were conducted. The cost-benefit of NIPT for Down syndrome was analyzed.@*RESULTS@#NIPT was carried out for 149 165 pregnant women and succeeded in 148 749 cases (99.72%), for which outcome were available in 148 538 (99.86%). 90% of pregnant women from the region accepted the screening with NIPT. 415 (0.27%) were diagnosed as high risk. Among these, 381 (91.81%) accepted amniocentesis, which led to the diagnosis of 212 cases of trisomy 21 (PPV=85.14%), 41 cases with trisomy 18 (PPV=48.81%) and 10 cases with trisomy 13 (PPV=20.83%). The sensitivity and specificity of NIPT for trisomy 21, trisomy 18 and trisomy 13 were (97.70%, 99.98%), (97.62%, 9.97%) and (100%, 99.97%), respectively. In addition, 213 and 30 cases were diagnosed with sex chromosomal aneuploidies (PPV=46.2%) and other autosomal anomalies (PPV=16.57%), respectively. For Down syndrome screening, the cost and benefit of the project was 120.79 million yuan and 1,056.95 million yuan, respectively. The cost-benefit ratio was 1: 8.75, and safety index was 0.0035.@*CONCLUSION@#NIPT is a highly accurate screening test for trisomy 21, which was followed by trisomy 18 and sex chromosomal aneuploidies, while it was less accurate for other autosomal aneuploidies. The application of NIPT screening has a high health economical value.

Preparation and evaluation of quality management samples for noninvasive prenatal screening / 中华医学遗传学杂志

OBJECTIVE@#To prepare a quality control sample for non-invasive prenatal screening (NIPS) and evaluate its quality and stability.@*METHODS@#According to the biological characteristics of cell-free fetal DNA derived from the plasma of pregnant women, the simulated samples were prepared by mixing genomic DNA fragments derived from individuals with trisomy 21, trisomy 18 and trisomy 13 and background plasma. The samples were then compared with commercially made quality control products tested on various NIPS platforms and stored at -80℃, -20℃, 4℃, 24℃ and 37℃ for various periods of time.@*RESULTS@#The simulated samples have attained the expected results and could be detected on various platforms and stored at -80℃and -20℃ for at least 30 days.@*CONCLUSION@#A simulated sample was successfully prepared and possessed good stability. It can be used as the quality control sample for NIPS.

The value of re-sampling for patients who had failed non-invasive prenatal testing due to low cell-free fetal DNA fraction / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of re-sampling for patients who had failed non-invasive prenatal testing (NIPT) due to low cell-free fetal DNA (cffDNA) fraction.@*METHODS@#Clinical data of 20 387 patients undergoing NIPT test was reviewed. The patients were re-sampled when initial blood test did not yield a result due to cffDNA fraction. The results were analyzed, and the outcome of pregnancy was followed up.@*RESULTS@#Among all samples, 17 (0.08%) had failed to yield a result due to low cffDNA fraction, all of which accepted re-sampling. A result was attained in 16 cases, with a success rate of 94.12%. Only one sample had failed the re-test.@*CONCLUSION@#For patients who had failed the initial NIPT due to low cffDNA fraction, re-sampling should be considered with gestational week and ultrasound results taken into consideration.

Identification of pathogenic variant and preimplantation genetic testing for a Chinese family affected with osteogenesis imperfecta / 中华医学遗传学杂志

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.

First Baby Born in Brazil after Simultaneous Diagnosis through Non-Invasive and Conventional PGT-A / Primeiro bebê nascido no Brasil após diagnóstico simultâneo por PGT-A não-invasivo e convencional

Abstract Non-invasive preimplantation genetic testing for aneuploidies (niPGT-A) aiming to assess cell-free embryonic DNA in spent culturemedia is promising, especially because it might overcome the diminished rates of implantation caused by the inadequate performance of trophectoderm (TE) biopsy. Our center is part of the largest study to date assessing the concordance between conventional PGT-A and niPGT-A, and we report here the delivery of the first baby born in Brazil using niPGT-A. The parents of the baby were admitted to our center in 2018. They did not present history of infertility, and they were interested in using in vitro fertilization (IVF) and PGT-A in order to avoid congenital anomalies in the offspring. A total of 11 (3 day-5 and 8 day-6) expanded blastocysts were biopsied, and the spent culture media (culture from day-4 to day-6) from 8 day-6 blastocysts were collected for niPGT-A. Overall, 7 embryos yielded informative results for trophectoderm (TE) and media samples. Among the embryos with informative results, 5 presented concordant diagnosis between conventional PGTA and niPGT-A, and 2 presented discordant diagnosis (1 false-positive and one falsenegative). The Blastocyst 4, diagnosed as 46, XY by both niPGT-A and conventional PGTA, was warmed up and transferred, resulting in the birth of a healthy 3.8 kg boy in February 2020. Based on our results and the recent literature, we believe that the safest current application of niPGT-A would be as a method of embryo selection for patients without an indication for conventional PGT-A. The approximate 80% of reliability of niPGT-A in the diagnosis of ploidy is superior to predictions provided by other noninvasive approaches like morphology and morphokinetics selection.

Resumo Abordagens para o teste genético pré-implantacional não-invasivo para aneuploidias (non-invasive preimplantation genetic testing for aneuploidies, niPGT-A, em inglês) com o objetivo de avaliar o DNA embrionário livre são promissoras, especialmente porque estas podem reverter as menores taxas de implantação causadas por inadequada biópsia de trofectoderma (TE). Nesse contexto, nosso centro é parte do maior estudo atual que avalia as taxas de concordância entre PGT-A convencional e niPGT-A, e relatamos aqui o nascimento do primeiro bebê brasileiro após niPGT-A. Os pais do bebê foram admitidos no nosso centro em 2018. Eles não apresentavam histórico de infertilidade, e estavam interessados em utilizar os tratamentos de fertilização in vitro (FIV) e PGT-A para evitar anomalias congênitas na progênie.Umtotal de 11 blastocistos expandidos (3 do dia-5 e 8 do dia-6) foram submetidos a biópsia, e os meios de cultivo condicionados (cultivo do dia-4 ao dia-6) de 8 blastocistos do dia-6 foram coletados para niPGT-A. No total, resultados informativos para as amostras de TE e dos meios foram obtidos para sete embriões. Entre os embriões com resultado informativo, 5 apresentaram diagnóstico concordante entre PGT-A convencional e niPGT-A, e 2 apresentaram diagnóstico discordante (1 falso positivo e 1 falso negativo). O Blastocisto 4, diagnosticado como 46, XY por ambos niPGT-A e PGT-A convencional, foi desvitrificado e transferido, o que resultou no nascimento de ummenino saudável, que pesava 3,8 kg, em fevereiro de 2020. Com base em nossos resultados e literatura contemporânea, acreditamos que a aplicação atualmais segura do niPGT-A seria como método de seleção embrionária para pacientes sem indicação ao PGT-A convencional. A confiabilidade aproximada de 80% do niPGT-A para determinação da ploidia ainda é superior àquela obtida com abordagens não invasivas, como seleção morfológica ou morfocinética.

Importancia de la determinación de variantes en el número de copias en neonatos con aneuploidías autosómicas / Importance of determining variations in the number of copies in newborns with autosomal aneuploidies

Resumen | Introducción. Las aneuploidías son trastornos genéticos frecuentes en la práctica clínica; sin embargo, se conoce poco sobre las otras variantes genéticas que modifican el fenotipo final. Objetivo. Determinar las variantes en el número de copias y las regiones con pérdida de heterocigosidad autosómica mayor de 0,5 % o de regiones mayores de 10 Mb en neonatos con aneuploidías autosómicas. Materiales y métodos. Se hizo el análisis cromosómico por micromatrices a los neonatos con aneuploidías autosómicas (n=7), trisomía 21 (n=5) y trisomía 18 (n=2) evaluados en los hospitales Antonio Lorena y Regional de Cusco, Perú, en el 2018. Resultados. En dos neonatos se encontraron variantes en el número de copias, patogénicas o probablemente patogénicas, en regiones diferentes al cromosoma 21 o al 18. Además, se observaron dos variantes del número de copias con más de 500 kpb de patogenia desconocida. Conclusiones. Si bien el número de pacientes era muy reducido, es importante resaltar que se encontraron otras variantes en el número de copias que se han descrito asociadas con trastornos del neurodesarrollo, varias anomalías congénitas, hipoacusia y talla baja o alta, entre otras, lo que probablemente influye negativamente en el fenotipo de este grupo de pacientes.

Abstract | Introduction: Aneuploidies are frequent genetic disorders in clinical practice. However, little is known about other genetic variants that may influence the final phenotype. Objective: To determine the variations in the number of copies and regions with homozygosity greater than 0.5% or larger than 10 Mb in newborns with autosomal aneuploidies. Materials and methods: We performed a chromosomal microarray analysis on newborns with autosomal aneuploidies (n=7), trisomy 21 (n=5), and trisomy 18 (n=2) evaluated at the Hospital Antonio Lorena and Hospital Regional of Cusco, Perú, during 2018. Results: We found pathogenic and probably pathogenic variants in the number of copies in other genomic regions different to chromosomes 21 or 18 in two neonates. Additionally, we found two variants bigger than 500 kpb of unknown pathogenicity. Conclusions: Although the number of analyzed individuals was small, it is important to highlight that we found other variants in the number of copies that have been described in association with neurodevelopmental disorders, congenital anomalies, deafness, and short/ tall stature, among others, in almost half of them, which will probably impact the phenotype negatively in patients with aneuploidies.

Association of fetal cardiac structural abnormalities and chromosomal aneuploidies and copy number variations / 中华医学遗传学杂志

OBJECTIVE@#To investigate the association of fetal cardiac structural abnormalities with chromosomal aneuploidies and copy number variations (CNVs) in amniocytes.@*METHODS@#328 pregnant women were subjected to fetal ultrasonography and chromosomal microarray analysis (CMA). Based on the fetal heart structure, the subjects were divided into normal (n=273) and abnormal groups (n=55). The detection rates of chromosomal aneuploidies and CNVs were compared between the two groups. Spearman method was used to assess the association between the results and fetal cardiac structural abnormalities.@*RESULTS@#The detection rates for chromosomal aneuploidies and CNVs in the abnormal group were significantly higher than that in the normal group (P< 0.05), and the incidence of fetal cardiac structural abnormalities was strongly associated with chromosomal aneuploidies and CNVs (P< 0.05).@*CONCLUSION@#Fetal chromosomal aneuploidies and CNVs are strongly associated with cardiac structural abnormalities.

Consensus on technological standards for non-invasive prenatal screening of pathogenic copy number variations by high-throughput sequencing of maternal plasma cell-free DNA / 中华医学遗传学杂志

Genomic disorders caused by pathogenic copy number variation (pCNV) have proven to underlie a significant proportion of birth defects. With technological advance, improvement of bioinformatics analysis procedure, and accumulation of clinical data, non-invasive prenatal screening of pCNV (NIPS-pCNV) by high-throughput sequencing of maternal plasma cell-free DNA has been put to use in clinical settings. Specialized standards for clinical application of NIPS-pCNV are required. Based on the discussion, 10 pCNV-associated diseases with well-defined conditions and 5 common chromosomal aneuploidy syndromes are recommended as the target of screening in this consensus. Meanwhile, a standardized procedure for NIPS-pCNV is also provided, which may facilitate propagation of this technique in clinical settings.

Analysis to the failure rate and causes of noninvasive prenatal testing based on high-throughput sequencing / 中华医学遗传学杂志

OBJECTIVE@#To analyze the cause and pregnancy outcome for non-reportable cell-free DNA (cfDNA) results during non-invasive prenatal testing (NIPT).@*METHODS@#cfDNA was extracted from maternal plasma from 5898 singleton pregnancies at 12 to 22 gestational weeks and underwent NIPT with strict quality control standards. For those with sub-standard results, redraw or invasive prenatal procedures were recommended.@*RESULTS@#Among the 5898 cases, 32 have failed for the initial NIPT, including 17 cases with substandard cffDNA%, 10 cases with data fluctuation after twice library constructing and sequencing, and 5 cases with unidentifiable sex chromosome abnormalities. For these 32 cases, 2 directly underwent amniocentesis, and karyotyping analysis showed both were normal. Six of the 30 redrawn cases finally turned out to be nonreportable. The final nonreportable rate was therefore 0.1% (8/5898). Of the redrawn cases, 1 trisomy 21, 1 trisomy 18 and 1 trisomy 13 high risk-cases were identified, which were all confirmed to be false positive. Among the 6 nonreportable cases, 2 women underwent invasive prenatal testing, and 1 was found to have a normal fetal karyotype, while another was found to have an abnormal karyotype of mos45,X[32]/46,XY[18]. The other 4 nonreportable cases who did not accept invasive prenatal testing have all reported normal child development at follow-up.@*CONCLUSION@#The main reason for nonreportable NIPT results was low cffDNA%. The high success rate of the redrawn cases has effectively increased the overall NIPT success rate and reduced the number of the cases necessitating invasive prenatal diagnosis. The initially nonreportable women may consider retesting after careful counseling with informed consent.

Analysis of the results of chromosomal trisomies 21, 18 and 13 screening among 40 628 women by non-invasive prenatal testing / 中华医学遗传学杂志

OBJECTIVE@#To assess the clinical value of non-invasive prenatal testing (NIPT) for the screening of trisomy and copy number variations (CNVs) of chromosomes 21, 18 and 13.@*METHODS@#From January 2015 to December 2019, 40 628 pregnant women underwent NIPT testing using high-throughput sequencing and bioinformatics analysis to test the cell-free fetal DNA in maternal plasma. High-risk pregnant women underwent invasive prenatal diagnosis, while low-risk ones were followed up by telephone.@*RESULTS@#The three most common indications included intermediate risk of serological screening, high risk of serological screening and advanced maternal age. Among all pregnant women, 257 cases were detected as trisomy 21, 18 and 13 (170, 49 and 38 cases, respectively). 227 cases chose invasive prenatal diagnosis, with respectively 122, 28 and 10 cases confirmed. The positive predictive value (PPV) was 81.33% (122/150), 65.12% (28/43), 29.41% (10/34), respectively. Two false negative cases of trisomy 18 were found during follow-up. Meanwhile, NIPT has detected 46 cases (15, 16 and 15 cases, respectively) CNVs on chromosomes 21, 18 and 13, among which 37 cases underwent invasive prenatal diagnosis. There were 5, 3 and 5 positive cases, which yielded a PPV of 41.67% (5/12), 25%(3/12) and 33.33%(5/15), respectively. Two other chromosome CNVs were accidentally discovered among the false positive samples.@*CONCLUSION@#The incidence of chromosomal abnormalities in the serological screening high-risk group was 52.02%, which was significantly higher than other groups. NIPT has a high sensitivity and specificity for the screening of trisomies 21, 18 and 13, while its accuracy for detecting CNVs of chromosomes 21, 18 and 13 needs to be improved. As a screening method, NIPT has a great clinical value, though there are still limitations of false positive and false negative results.Comprehensive pre- and post-test genetic counseling should be provided to the patients.

Analysis of the effect of expanded non-invasive prenatal testing in prenatal screening population during pregnancy / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical effect of expanded non-invasive prenatal testing (NIPT-plus) for prenatal screening.@*METHODS@#The screening result, prenatal diagnosis and pregnancy outcome of 3700 pregnant women who volunteered NIPT-plus screening at our center from September 2018 to December 2019 were reviewed.@*RESULTS@#Among the 3700 pregnant women, 74(2.0%) were scored positive for clinically significant fetal chromosomal abnormalities and underwent NIPT-plus screening. Sixty three women with a high risk underwent invasive prenatal diagnosis, among whom 19 were diagnosed, which yielded a positive predictive value (PPVs) of 30.2% (19/63). Statistical analysis showed that NIPT-plus has higher PPVs for common aneuploidies and low-to-medium PPVs for sex chromosome aneuploidies and microdeletion/microduplication syndromes.@*CONCLUSION@#As a screening technique, NIPT-plus has broader applications compared with conventional techniques, and has reference value for clinicians and pregnant women during pregnancy.

Is it necessary to choose NIPT-plus for pregnant women who opt for non-invasive prenatal testing? A study of 50 cases / 中华医学遗传学杂志

OBJECTIVE@#To explore whether it is necessary to choose NIPT-plus for the prenatal screening of pregnant women.@*METHODS@#The results of NIPT and NIPT-plus sequencing data, fetal DNA concentration, prenatal diagnosis and pregnancy outcome of 50 pregnant women were compared.@*RESULTS@#Compared with NIPT, NIPT-plus attained similar fetal DNA concentration and a 4.4-fold increase in sequencing data. NIPT was able to detect 4 cases of 21-trisomy, 2 cases of 18-trisomy, and 9 cases of sex chromosome aneuploidies (SCAs) signaled by NIPT-plus, but missed one 18-trisomy, and failed to detect rare chromosome aneuploidies (RCAs) and microdeletion/microduplication syndromes (MMS). The PPVs of NIPT-plus for 21-trisomy, 18-trisomy, SCAs, MMS and RCAs were 100%, 100%, 44.4%, 30.4% and 0%, respectively. And those of NIPT for 21-trisomy, 18-trisomy, and SCAs were 100%, 100%, and 44.4%, respectively.@*CONCLUSION@#It is necessary for pregnant women to select NIPT-plus to improve the detection rate of common trisomies, SCAs and disease-specific MMS, therefore reduce the occurrene of birth defect.

Application of mapping allele with resolved carrier status technique for preimplantation genetic testing in carriers with balanced chromosomal translocations / 中华医学遗传学杂志

OBJECTIVE@#To assess the application value of mapping allele with resolved carrier status (MaReCs) technique for preimplantation genetic testing (PGT).@*METHODS@#The characteristics of MaReCs for PGT and outcome of patients were retrospectively analyzed.@*RESULTS@#Compared with those who could not use the technique, carriers who have used the MaReCs technique were younger, had significantly higher level of anti-Mullerian hormone, more antral follicles, occytes, mature occytes, biopsied embryos and euploid embryos, and lower risks for de novo chromosomal abnormality (P 0.05). Carriers undergoing MaReCs test could preferentially select embryos with normal chromosome structures for the transfer.@*CONCLUSION@#Application of MaReCs has a prerequisite for having a minimum number of occytes and biopsied embryos and using discarded embryos sometimes. MaReCs is efficient for the detection of carrier status of embryos and attaining higher rate of pregnancy and live birth, which can significantly improve the outcome for couples carrying chromosomal translocations.

Preliminary study on the application of third-generation sequencing technology for the detection of chromosomal aneuploidies / 中华医学遗传学杂志

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.

Effectiveness of non-invasive prenatal screening for the detection of fetal sex chromosome anomalies / 中华医学遗传学杂志

OBJECTIVE@#To evaluate the efficacy of non-invasive prenatal screening (NIPS) for fetal sex chromosome anomalies.@*METHODS@#A retrospective analysis was carried out for 20 802 women undergoing NIPS screening. For 165 cases suspected for fetal sex chromosomal anomalies, the results of invasive prenatal diagnosis were obtained.@*RESULTS@#Among the 165 cases suspected for fetal sex chromosome anomalies, 129 have accepted invasive prenatal diagnosis, and 45 were confirmed, which yielded a positive predictive value of 34.88%. These included 16 cases of 47,XYY, 10 cases of 47,XXY, 6 cases of 45,X/46,XX, 5 cases of 47,XXX, 3 cases of 45,X, 1 case of 45,X/46,X,i(X)(q10), 1 case of 45,X/46,X,del(X)(q22), 1 case of 46,X,del(X)(q22), 1 case of 46,X,del(X)(p11) and 1 case of Xp22.31 1.2 Mb deletion.@*CONCLUSION@#NIPS has limited value for detecting fetal sex chromosome anomalies. Karyotyping analysis combined with other diagnostic techniques can offer effective prenatal diagnosis for suspected cases.

Clinical characteristics and prenatal diagnosis of fetuses with sex chromosomal aneuploidies detected by non-invasive prenatal testing during early and midterm pregnancies / 中华医学遗传学杂志

OBJECTIVE@#To analyze the indication, karyotyping result, ultrasound finding, pregnancy decision and follow-up of fetuses with sex chromosome aneuploidies (SCA) detected by non-invasive prenatal testing (NIPT) during early and midterm pregnancies.@*METHODS@#The results of 225 singleton pregnancies with fetal SCA detected by NIPT were reviewed and analyzed.@*RESULTS@#The 225 cases included 45,X (n=37), 47,XXY (n=74), 47,XXX (n=50), 47,XYY (n=56) and mosaicisms (n=8), among which 121 (53.8%) have opted to terminate the pregnancy, including 45,X (n=31), 47,XXY (n=61), 47,XXX (n=14), 47,XYY (n=12) and 3 mosaicisms. The remainder 104 (46.2%) have elected to continue with the pregnancy, among which three have opted to terminate due to abnormalities detected by ultrasonography, and two had spontaneous abortions.@*CONCLUSION@#NIPT as a first-tier screening method can effectively detect fetal trisomies 21, 13 and 18 as well as SCA. The types of fetal SCA and presence of ultrasound abnormalities are critical factors for the termination of pregnancy.