Prenatal diagnosis and genetic analysis of a special case with complex structural rearrangements of chromosome 8 / 中华医学遗传学杂志

OBJECTIVE@#To present on a prenatally diagnosed case with complex structural rearrangements of chromosome 8.@*METHODS@#Chromosome karyotyping, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) were carried out for a fetus with increased nuchal thickness.@*RESULTS@#The karyotype of the amniotic fluid sample showed extra materials on 8p. FISH revealed a centromeric signal at the terminal of 8p with absence of telomeric signal. CMA revealed partial deletion of 8p23.3 [(208049_2256732)×1], partial duplication of 8p23.3p23.2 [(2259519_3016818)×3], and partial duplication of 8q [8q11.1q12.2(45951900_60989083)×3].@*CONCLUSION@#The complex structural rearrangements of chromosome 8 in this case has differed from the commonly seen inv dup del(8p).

Development of plasma quality control material for non-invasive prenatal detection of fetal aneuploidy / 中华检验医学杂志

Objective:To develop a self-made plasma quality control material for non-invasive prenatal testing (NIPT) and evaluate its performance.Methods:139 NIPT-negative maternal plasmas stored in the genetic department of Shaoxing maternal and child health hospital from January 1, 2019 to June 30, 2021 were divided into male groups (19 cases) and female groups (120 cases) according to the neonatal gender. 9360 cases from September 2020 to September 2021 were enrolled as clinical validation cases.First step, 200 μl plasma from a 47 years-old non-pregnant healthy women was used as a matrix. Different amounts (0.1, 0.2, 0.5, 2.5, and 5 μl) of positive DNA from fetal chromosome aneuploidy (T21, T18, T13) detection kit were added. The appropriate volume of positive DNA was 0.5 μl according to the test results. Second step,Plasma in male and female group was treated as matrix. 0.5 μl positive DNA was added per 205 μl. Plasma matrix from female group showed good repeatability and the sensitivity was 100%.Third step, evaluate the self-made plasma quality control material, including storage stability, matrix uniformity and repeatability, and the effect of different batch numbers of positive DNA, by calculating Z score and the CV of fetal DNA concentration (FF).Results:Plasma matrix from female group showed good repeatability and the sensitivity was 100%, while the sensitivity of male group was only 84%. The CV of FF in female matrix was 3.9% in the repetitive experiments. After adding 0.5 μl positive DNA, the mean FF of self-made positive plasma quality control was 5.63%±0.42%, Z values>6, and the CV was 7% after storage of three months. Considering the concentration variation of positive DNA in different lots, 1 μl of positive DNA should be added when the FF of positive DNA is lower than 10%.Used in 9360 clinical cases from September 2020 to September 2021, all positive plasma quality control materials showed positive results, and the positive predictive value of trisomy 21 was 100%.Conclusions:The NIPT self-made positive plasma quality control material has been successfully developed in this study. The preliminary experimental results show that it has good repeatability and stability, which is suitable for clinical application.

Application of BACs-on-Beads in prenatal diagnosis / 中华医学遗传学杂志

OBJECTIVE@#To explore the value of BACs-on-Beads (BoBs) for the practice of prenatal diagnosis.@*METHODS@#The results of chromosomal karyotyping and BoBs of 1773 prenatal samples were compared. Microdeletions and microduplications detected by BoBs were subjected to chromosome microarray analysis (CMA) with informed consent from patients.@*RESULTS@#BoBs has detected 46 cases of common aneuploidies involving chromosomes 13, 18, and 21, and 16 cases involving X and Y chromosomes. For 4 fetuses with normal results by BoBs, karyotyping analysis of amniotic fluid sample suggested low percentage mosaicisms (< 20%). BoBs has detected none of the 9 common microdeletions, but 14 male fetuses with Xp22 microdeletions and 5 with other microdeletions/microduplications. In 10 cases, the couples had chosen CMA verification, and the results were all consistent.@*CONCLUSION@#As a rapid diagnostic technique, BoBs has a high accuracy for common aneuploidies, and is capable of discovering certain chromosome microdeletions and microduplications. The difficulty lies in the inability to detect low proportion mosaicisms and the consultation following detection for male fetuses carrying Xp22 microdeletions.

Genetic analysis of a 45,X male fetus / 中华医学遗传学杂志

OBJECTIVE@#To analyze the prenatal diagnosis procedure for a 45,X male fetus.@*METHODS@#A 31-year-old women underwent amniocentesis due to a moderate risk of trisomy 21. The fetal cells were subjected to chromosomal karyotyping, BACs-on-Beads (BoBs) assay, chromosomal microarray analysis and fluorescence in situ hybridization.@*RESULTS@#Combined analyses revealed that the whole of Yp has translocated to 21p, which yielded a fetal karyotype of 45,X,dic(Y;21)(q11;p11).ishdic(Y;21)(SRY+,CEPY+;CEP21+).@*CONCLUSION@#BoBs and modified N-banding method are helpful for the diagnosis of 45,X male fetus with Yp translocation.

Study of two cases of prenatally detected small supernumerary marker chromosomes / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the origin of two prenatally detected small supernumerary marker chromosomes (sSMCs).</p><p><b>METHODS</b>The sSMCs were analyzed with combined G-banding, C-banding, fluorescence in situ hybridization (FISH), and single nucleotide polymorphisms array (SNP-array) techniques.</p><p><b>RESULTS</b>In case 1, G-banding analysis has identified a 47,XY,+mar karyotype. Affymetrix CytoScan 750K Array scan has suggested arr 15q11.2q12(22 770 421-26 604 587)?, while FISH analysis suggested 47,XN,+mar.ish i(15)(q12)(D15Z1+,SNRPN++,PML-). In case 2, G-banding analysis has suggested 46,X,+mar/46,XY, FISH analysis showed two SRY hybridization signals, indicating 46,X,i(Y)(p10)/46,XY.</p><p><b>CONCLUSION</b>Multiple techniques needed be applied for verification of the origin of sSMCs identified in prenatal diagnosis.</p>

Application of modified three-step fluorescence in situ hybridization in prenatal diagnosis / 中华检验医学杂志

Objective To investigate a simple and efficient fluorescence in situ hybridization method for prenatal diagnosis.Methods Thirty-six cases of chorionic villus samples were hybridized with probes 18/X/Y,13/21 by using traditional cuhure methods and modified three-step methods in controlled experimentation during 2012 to 2013.The hybridization rate and fluorescence signals were analyzed.Results A total of 72 hybrid zone were detected.Probe 21/13 hybridization rate and fluorescence signals of three-step modified methods were higher than that of traditional methods(99.72％ ±0.42％ vs 85.90％ ±4.15％,t =20.4,P ＜0.01; 2.58 ±0.50 vs 1.52 ± 0.55,t =7.53,P ＜0.01).Probe 18/X/Y has the same hybridization rate and fluorescence signals between three-step modified methods and traditional methods (99.57％ ±0.53％ vs99.70％ ±0.42％,t=1.30,P＞0.05; 2.22±0.42 vs2.36±0.48,t=1.57,P＞0.05).The coincidence rate of two methods was 100％ (36/36).Conclusion The modified fluorescence in situ hybridization three-step methods in the study was simple,rapid,effective and environment-friendly.At the same time,it has some defects such as the signals of 18/X/Y was not concentrated enough.Further exploration is needed.