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.

Dandy-walker syndrome and microdeletions on chromosome 7 / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate genetic etiology of Dandy-Walker syndrome with array-based comparative genomic hybridization (array-CGH).</p><p><b>METHODS</b>Eight fetuses with Dandy-Walker malformations but normal karyotypes by conventional cytogenetic technique were selected. DNA samples were extracted and hybridized with Affymetrix cytogenetic 2.7 M arrays by following the manufacturer's standard protocol. The data were analyzed by special software packages.</p><p><b>RESULTS</b>By using array-CGH technique, common deletions and duplication on chromosome 7p21.3 were identified in three cases, within which were central nervous system disease associated genes NDUFA4 and PHF14.</p><p><b>CONCLUSION</b>Copy number variations (CNVs) of chromosome 7p21.3 region are associated with Dandy-Walker malformations which may be due to haploinsufficiency or overexpression of NDUFA4 and PHF14 genes.</p>

Application of fluorescence in situ hybridization to prenatal diagnosis of aneuploidy in 110 uncultured amniotic fluid samples / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To optimize the prenatal diagnosis platform by using domestically made fluorescence in situ hybridization(FISH) kit and to explore the clinical application of FISH to rapid prenatal diagnosis of a wide range of chromosomal abnormalities.</p><p><b>METHODS</b>Amniotic fluid samples from 110 pregnant women were studied with the rapid prenatal diagnosis method of FISH and the conventional cell culture method of karyotyping, the results from both methods were compared.</p><p><b>RESULTS</b>Four cases of trisomy 21, 1 case of trisomy 18, 58 cases of 46, XX, and 47 cases of 46, XY were detected by FISH in the 110 amniotic fluid samples. It is concordant with the results from conventional karyotype analysis. The concordance rate is 100%.</p><p><b>CONCLUSION</b>Domestically made FISH kit can be used to rapidly and accurately detect the most common chromosome aneuploidies by using less sample volume while the price is relatively low. FISH can be a reliable and rapid prenatal diagnostic tool as an adjunct to classical cytogenetic study. It can be used for rapid and accurate prenatal diagnosis of women with high risk of maternal serum screening.</p>

Application of spectral karyotyping in diagnosis of complex chromosome aberration / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the value of spectral karyotyping (SKY) to identify the complex chromosome aberration.</p><p><b>METHODS</b>Four cases were selected that can not be identified by standard cytogenetic techniques. The chromosome specimens were detected by the routine SKY method, and the results were analyzed by the SKY View software.</p><p><b>RESULTS</b>By using SKY a case of complex chromosome rearrangements and two cases of chromosome duplication were identified. However it could not identify the chromosome inversion and the breakpoint of chromosome aberration.</p><p><b>CONCLUSION</b>SKY may be a valuable tool in identification of complex chromosome translocation, rearrangement, minute aberration and unknown derivative chromosomes. Though SKY can not replace the standard cytogenetic techniques, but it will be the benefit supplementary.</p>

Polymorphisms analysis of short tandem repeat loci D21S1433, D21S1442, D21S1444, D21S2051 in Guangdong Han nationality in China / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To investigate the polymorphic distribution of short tandem repeat (STR) sequences D21S1433, D21S1442, D21S1444, D21S2051 in Guangdong Han nationality in China.</p><p><b>METHODS</b>Using quantitative fluorescens PCR technology, the authors analyzed 200 unrelated samples to acknowledge the allele frequency, heterozygosity and other genetic information.</p><p><b>RESULTS</b>D21S1433, D21S1442, D21S1444, D21S2051 were tested in 200 samples, which were tested to be statistical according to Hardy-Weinberg equilibrium (P> 0.05), 9, 10, 9 and 5 alleles were detected separately in each STRs. The heterozygosity of each STR was 0.818, 0.820, 0.770, and 0.261. The polymorphic information content > 0.7 in D21S1433, D21S1442, D21S1444, while D21S2051 owned only 0.247 polymorphic information.</p><p><b>CONCLUSION</b>D21S1433, D21S1442, D21S1444 are found to have high heterozygosity and polymorphic information content, and they could provide useful markers for genetic purposes, while D21S2051 is not informative in Guangdong Han nationality in China.</p>

Application of real-time fluorescence quantitative PCR to rapid molecular detection of Down's syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To develop a rapid and reliable technique for the detection of Down's syndrome.</p><p><b>METHODS</b>The peripheral blood samples were collected from twenty-five Down's syndrome patients and fifty normal individuals. Four polymorphic loci on chromosomes 21, 1, 19 were amplified by real-time fluorescence quantitative PCR, and then four pairs of deltaCt values were analytically compared between the two groups.</p><p><b>RESULTS</b>The deltaCt values of Down's syndrome patients were significantly lower than those of normal individuals, and the reference ranges for clinical application were primarily established. The difference between the two groups was highly significant (P < 0.001), and the reference ranges between the two groups were not overlapped. Real-time quantitative PCR technique can effectively differentiates Down's syndrome samples from the normal fetuses; furthermore, the results were consistent with those of the karyotype analysis.</p><p><b>CONCLUSION</b>Real-time quantitative PCR is a fast and reliable method that may provide a new approach for rapid detection of Down's syndrome.</p>