Report content and prenatal diagnosis of non-invasive prenatal testing for sex chromosome aneuploidy / 中华妇产科杂志

Objective: To analyze the report content, the methods and results of prenatal diagnosis of high risk of sex chromosome aneuploidy (SCA) in non-invasive prenatal testing (NIPT). Methods: A total of 227 single pregnancy pregnant women who received genetic counseling and invasive prenatal diagnosis at Drum Tower Hospital Affiliated to the Medical School of Nanjing University from January 2015 to April 2022 due to the high risk of SCA suggested by NIPT were collected. The methods and results of prenatal diagnosis were retrospectively analyzed, and the results of chromosome karyotype analysis and chromosome microarray analysis (CMA) were compared. The relationship between NIPT screening and invasive prenatal diagnosis was analyzed. Results: (1) Prenatal diagnosis methods for 277 SCA high risk pregnant women included 73 cases of karyotyping, 41 cases of CMA and 163 cases of karyotyping combined with CMA, of which one case conducted amniocentesis secondly for further fluorescence in situ hybridization (FISH) testing. Results of invasive prenatal diagnosis were normal in 166 cases (59.9%, 166/277), and the abnormal results including one case of 45,X (0.4%, 1/277), 18 cases of 47,XXX (6.5%, 18/277), 36 cases of 47,XXY (13.0%, 36/277), 20 cases of 47,XYY (7.2%, 20/277), 1 case of 48,XXXX (0.4%, 1/277), 20 cases of mosaic SCA (7.2%, 20/277), 5 cases of sex chromosome structural abnormality or large segment abnormality (1.8%, 5/277), and 10 cases of other abnormalities [3.6%, 10/277; including 9 cases of copy number variation (CNV) and 1 case of balanced translocation]. Positive predictive value (PPV) for SCA screening by NIPT was 34.7% (96/277). (2) Among the 163 cases tested by karyotyping combined with CMA, 11 cases (6.7%, 11/163) showed inconsistent results by both methods, including 5 cases of mosaic SCA, 1 case of additional balanced translocation detected by karyotyping and 5 cases of additional CNV detected by CMA. (3) NIPT screening reports included 149 cases of "sex chromosome aneuploidy"(53.8%, 149/277), 54 cases of "number of sex chromosome increased" (19.5%, 54/277), and 74 cases of "number of sex chromosome or X chromosome decreased" (26.7%, 74/277). The PPV of "number of sex chromosome increased" and "number of sex chromosome or X chromosome decreased" were 72.2% (39/54) and 18.9% (14/74), respectively, and the difference was statistically significant (χ2=34.56, P<0.01). Conclusions: NIPT could be served as an important prenatal screening technique of SCA, especially for trisomy and mosaicism, but the PPV is comparatively low. More information of NIPT such as the specific SCA or maternal SCA might help improving the confidence of genetic counseling and thus guide clinic management. Multi technology platforms including karyotyping, CMA and FISH could be considered in the diagnosis of high risk of SCA by NIPT.

Molecular genetics study of ED1 gene for two X-linked hypohidrotic ectodermal dysplasia families / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide genetic diagnosis and counseling for patients from two families affected with X-linked hypohidrotic ectodermal dysplasia.</p><p><b>METHODS</b>Potential mutation of the ED1 gene was screened by DNA sequencing. For family 1, multiplex ligation-dependent probe amplification (MLPA) analysis and haplotyping of ED1 gene were also carried out for prenatal diagnosis.</p><p><b>RESULTS</b>For the patient from family 1, deletion of the exon 1 of the ED1 gene and 2 short tandem repeat(STR) sites (DXS8269 and DXS1422) were detected. His daughter was carrier of the deletion. Upon prenatal diagnosis, the fetus was confirmed to be a normal male, for whom the haplotype of ED1 gene has differed from that of the proband. In family 2, a c.463C>T mutation in exon 3 of the ED1 gene was detected in the proband, whose mother was heterozygous for the same mutation.</p><p><b>CONCLUSION</b>The deletion (exon 1) and missense (R155C) mutation in ED1 gene have probably underlied the disease in the two families. During prenatal diagnosis, it may be necessary to obtain precise results through combining mutation detection and haplotype analysis of the ED1 gene.</p>

Mutation analysis and prenatal diagnosis of families affected with Duchenne and Becker muscular dystrophy / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutations for probands from families affected with Duchenne/Becker muscular dystrophy (DMD/BMD), and to carry out prenatal diagnosis through identification of female carriers.</p><p><b>METHODS</b>A total of 43 DMD/BMD families were recruited. Multiplex PCR was used to analyze 18 exons within hotspots for DMD gene deletions. Multiplex ligation-dependent probe amplification (MLPA) was used to detect potential deletions and duplications of DMD gene for 43 patients and 36 females from 32 families. Prenatal diagnosis was performed for 27 families.</p><p><b>RESULTS</b>Deletional mutations were detected in 26 patients with multiplex PCR. In addition, MLPA has detected 3 deletions and 6 duplicational mutations, and the ranges of mutations were all determined. Among 36 female members, 18 were determined as carriers of deletional mutations, 10 were excluded as mutation carriers. The status of remaining 8 could not be determined. For prenatal diagnosis, 3 out of 18 male fetuses were diagnosed as patients and 1 female fetus was identified as carrier.</p><p><b>CONCLUSION</b>MLPA is an accurate and reliable method for detecting deletional/duplicational mutations of DMD gene as well as for prenatal diagnosis and detection of female carriers.</p>

Mutation analysis and prenatal diagnosis of EXT1 gene mutations in Chinese patients with multiple osteochondromas / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Multiple osteochondromas (MO), an inherited autosomal dominant disorder, is characterized by the presence of multiple exostoses on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes which encode glycosyltransferases implicated in heparin sulfate biosynthesis.</p><p><b>METHODS</b>In this study, efforts were made to identify the underlying disease-causing mutations in patients from two MO families in China.</p><p><b>RESULTS</b>Two novel EXT1 gene mutations were identified and no mutation was found in EXT2 gene. The mutation c.497T > A in exon 1 of the EXT1 gene was cosegregated with the disease phenotype in family 1 and formed a stop codon at amino acid site 166. The fetus of the proband was diagnosed negative. In family 2, the mutation c.1430-1431delCC in exon 6 of the EXT1 gene would cause frameshift and introduce a premature stop codon after the reading frame being open for 42 amino acids. The fetus of this family inherited this mutation from the father.</p><p><b>CONCLUSIONS</b>Mutation analysis of two MO families in this study demonstrates its further application in MO genetic counseling and prenatal diagnosis.</p>

Molecular genetic study of MECP2 gene for a patient with typical Rett syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide genetic diagnosis and counseling for a 2-year-old girl with typical Rett syndrome through analyzing the methyl-CpG binding protein 2 (MECP2) gene.</p><p><b>METHODS</b>Potential mutation of the MECP2 gene was screened by DNA sequencing and multiplex ligation-dependent probe amplification (MLPA) analysis of members of the family as well as normal controls. Lymphocyte culture for karyotype analysis was carried out for the patient to exclude chromosomal abnormalities.</p><p><b>RESULTS</b>The karyotype of the girl was normal. No variation of the MECP2 gene was detected in the patient by direct sequencing. A heterozygosis variation, c.1072G>A in exon 4 of the MECP2 gene was detected in a normal female control, which was not found in other controls. The son and daughter of the female control were respectively heterozygous and homozygous carriers of the same mutation. By MLPA analysis, a heterozygosis deletion of exon 3 and part of exon 4 was detected in the patient. cDNA amplification and sequencing confirmed the presence of a 1176 bp deletion (c.27-1202del1176). The same deletion was not detected in the parents.</p><p><b>CONCLUSION</b>A large deletion in MECP2 gene was detected with MLPA in a patient featuring typical Rett syndrome. The same deletion was missed by sequencing analysis. With cDNA sequencing, the breakage point of the mutation can be mapped precisely.</p>

Diagnosis of 22q11 deletion and duplication in congenital heart disease by multiplex ligation dependent probe amplification / 中国当代儿科杂志

<p><b>OBJECTIVE</b>To investigate the clinical utility of multiplex ligation-dependent probe amplification (MLPA) for detecting 22q11 deletion and duplication in congenital heart disease (CHD) cases and to study the incidence of 22q11 deletion and duplicaton in different kinds of CHD.</p><p><b>METHODS</b>Forty eight probes of which 25 located in 22q11 low copy number region (LCR 22s A-H), 7 in 22q11 surrounding region (CES, 22q13) and 16 in chromosomes 4, 8, 10 and 17 were selected to detect 22q11 deletion and duplication in 181 preoperative children with CHD and 14 fetuses with serious CHD or CHD with multiple malformations. In these cases, karyotype analysis was also performed.</p><p><b>RESULTS</b>MLPA demonstrated that 7 cases had 22q11 deletion [6 cases from CLTCL1 to LZTR1(LCR A-D) and 1 case from CLTCL1 to PCQAP (LCR A-C)] and that 1 case had 22q11 duplication,spanning from ZNF74 to LZTR1(LCR B-D). The phenotypes of heart defect included ventricular septal defect, atrioventricular septal defect, pulmonary stenosis and tetralogy of Fallot. Karyotype analysis showed that 1 case had 21q deletion [46, XY, 21q], 1 case had mosaic trisomy 8 [47,XY, +8/46, XY(1:2)] and 4 cases had trisomy 21. One of the 4 cases with trisomy 21 had concurrent 22q11 duplication.</p><p><b>CONCLUSIONS</b>MLPA is a rapid, sensitive, site specific and relatively inexpensive method for diagnosis of 22q11 deletion and duplication in CHD. 22q11 deletion and duplication may cause various kinds of CHD, suggesting that genetic detection should be performed routinely in CHD patients.</p>