[Prenatal diagnosis of 22q11.2 microdeletion by multiplex ligation-dependent probe amplification].

OBJECTIVE: To explore the clinical value of multiplex ligation-dependent probe amplification (MLPA) technique performed in prenatal diagnosis of chromosome 22q11.2 microdeletion. METHODS: MLPA was performed to detect chromosome 22q11.2 mircodeletion in 62 fetuses with congenital heart defects by fetal echocardiography and a normal karyotype by standard G-banding analysis.For a 22q11.2 mircodeletion fetus, his parents were detected to know if it is inherited or de novo. The microdeletion was confirmed by array-based comparative genomic hybridization (arrayCGH). RESULTS: MLPA revealed five 22q11.2 mircodeletions in the 62 fetuses, and the positive detection rate was 8% (5/62). Among these, 4 cases carried the 3M typically deletion which all are de novo, and 1 case carried the 1.5M non-typically deletion which was inherited from his father.arrayCGH confirmed the 22q11.2 microdeletions and delineated the precise location and size of microdeletions. CONCLUSION: MLPA has clinical value in prenatal diagnosis of 22q11.2 mircodeletion, which could provide important genetic information for genetic consulting, pregnancy management and intervention after birth.

[Prenatal diagnosis of two fetuses with de novo small supernumerary markers by single nucleotide polymorphism array based comparative genomic hybridization].

OBJECTIVE: To explore the origins of small de novo mosaic supernumerary marker chromosomes (mars) in two fetuses, and to assess the feasibility of single nucleotide polymorphism array-based comparative genomic hybridization (SNP-array CGH) for prenatal molecular cytogenetic diagnosis. METHODS: Two fetuses with de novo were identified. SNP-array marker chromosomes was applied to define the location and range of marker chromosomes. The karyotype of fetus I was determined to be 47,XX,+ mar[23]/46,XX[16], and that of fetus II was 47,XX,+ mar. Multiplex ligation-dependent probe amplification (MLPA) was applied to verify the genomic imbalance found in fetus II. The karyotypes of parents were normal in both families. RESULTS: SNP-array CGH has indicated a 8.3 Mb duplication at 9p21.1-p21.3 in fetus I, and a 10.8 Mb duplication at 15q11.2-q13.3 in fetus II. MLPA has also confirmed a 15q terminal duplication in fetus II. CONCLUSION: Above cases have illustrated that SNP-array CGH is a rapid, powerful and sensitive technique which may be used for identify the origins of marker chromosomes in prenatal diagnosis.

[Array-based comparative genomic hybridization detection of copy number variations in a fetus with hypoplastic left-heart syndrome].

OBJECTIVE: To detect the copy number variations (CNVs) of a fetus with hypoplastic left-heart syndrome, and to assess the value of array-based comparative genomic hybridization (array-CGH) for molecular cytogenetic diagnosis. METHODS: The whole genome of a fetus with normal karyotype by G-banding was scanned and analyzed by array-CGH, and the CNVs was confirmed by multiplex ligation-dependent probe amplification (MLPA). RESULTS: Two submicroscopic CNVs [del(11)(q24.1-ter)(121951443-134449216, -12.50 Mb),dup(15)(q26.3)(96889082-100215359, -3.33 Mb)] were identified and mapped by array-CGH. MLPA test confirmed both CNVs. CONCLUSION: Del (11) (q24.1-ter) may contribute to hypoplastic left-heart syndrome of the fetus. For its high-resolution and high-accuracy, array-CGH has provided a powerful tool for detection of genomic imbalance.

[Cytogenetic analysis of a complex chromosomal imbalance 14q+ in a fetus featuring multiple congenital defects].

OBJECTIVE: To analyze chromosomal imbalance in a fetus presenting with congenital heart disease and mild lateral ventriculomegaly, and to investigate the correlation between genotype and phenotype. The etiology of the fetal congenital diseases was determined, and the feasibility of array-based comparative genomic hybridization (array-CGH) application in molecular cytogenetic diagnosis was evaluated. METHODS: Following conventional G-banding analysis, array-based comparative genomic hybridization (array-CGH) was applied to delineate the precise location and size of genomic imbalance. RESULTS: A de novo 46, XY, -14, +der14(q31)? karyotype was identified in the fetus by G-banding analysis. Array-CGH has verified the chromosomal imbalance to be 46, XY, -14, +der(12; 14) (p13; q32.33)del(14) (q32.33→ qter). CONCLUSION: del(14)(q32.33→ qter) is probably the predominant cause of the fetal congenital disease. For its high resolution and accuracy, array-CGH has provided a powerful tool for prenatal diagnosis and genetic counseling.

[Application of multiplex ligation-dependent probe amplification for rapid detection of aneuploidies in prenatal diagnosis].

OBJECTIVE: To determine the applicability of multiplex ligation-dependent probe amplification (MLPA) for rapid detection of aneuploidies in prenatal diagnosis. METHODS: A total of 561 prenatal samples were analyzed in parallel by MLPA and traditional karyotyping. Another 20 clinical samples with known common chromosome abnormalities were also determined by MLPA to evaluate the accuracy and reliability of MLPA. The results obtained from MLPA were compared with that from traditional karyotyping. RESULTS: The results were available within 48 h. A total of 38 aneuploidies were identified by MLPA, including 20 cases of trisomy 21, 10 cases of trisomy 18, 1 case of trisomy 13, 4 cases of Turner syndrome, 1 case of Klinefelter syndrome, 1 case of 47, XYY trisomy and 1 case of 48,XYY, +18. MLPA was able to detect all the expected aneuploidies with 100% accuracy. The results obtained from MLPA agreed with traditional karyotyping. Among 561 prenatal samples, the results of 550 samples were concordant with those of karyotyping, and the coincidence rate of MLPA was 98.04%. CONCLUSION: MLPA is a rapid, simple and reliable method for detection of the most common chromosome aneuploidies in prenatal diagnosis. MLPA is a valuable tool in prenatal clinical practice.

[Detection of cryptic copy number variations in a fetus with congenital heart disease by array-based comparative genomic hybridization].

OBJECTIVE: To detect the copy number variation (CNV) of a fetus with interrupted aortic arch and ventricular septal defect, in order to explore the underlying genetic causes of the congenital malformation, and investigate the feasibility of array-based comparative genomic hybridization (array-CGH) in molecular cytogenetic diagnosis. METHODS: The whole genome of the fetus with de novo apparently balanced translocations [46,XX,t(7;9)(q12;q21)] diagnosed by G-banding was scanned and analyzed by array-CGH, and the copy number variation was confirmed by fluorescence in situ hybridization (FISH). RESULTS: A pathologic submicroscopic CNV [del(22) (q11.2) (17 370 128-19 790 009, -2.42 Mb)] was identified and mapped by array-CGH. FISH test confirmed the microdeletion detected by array-CGH. CONCLUSION: The cryptic 22q11.2 deletion might be the reason leading to the congenital malformation of the fetus. This study provides evidence that apparently balanced translocations classified by conventional cytogenetic techniques may host additional submicroscopic CNVs which are not located at the breakpoints. Due to the high-resolution, high-throughput and high-accuracy, array-CGH is considered to be a powerful tool for submicroscopic CNVs detection.

[Prenatal genetic study of fetuses with congenital heart diseases].

OBJECTIVE: To investigate the genetic abnormalities of fetuses with congenital heart diseases (CHD), and to provide guidance for the management of pregnancy and genetic counseling. METHODS: Eighty-one fetuses with CHD detected by fetal echocardiography were analyzed by karyotyping after amniocentesis, cordocentesis or chorionic sampling. Then 22q11.2 deletion/duplication was detected by a competitive fluorescent multiplex short tandem repeat assay in 47 CHD fetuses without chromosomal abnormalities. With fluorescence in situ hybridization (FISH) using LSI dual color DNA probe, the deletion/duplication status was confirmed. RESULTS: Thirty-four of 81 CHD fetuses had chromosomal anomalies, and 1 of the 47 CHD fetuses without chromosomal anomalies had duplication at chromosome 22q11. The incidence of aneuploidy associated CHD was 43.2%. The rate of chromosomal anomalies is higher in the cases associated with extra-cardiac anomalies than in that with isolated CHD (64.5% versus 28.0%). In the 35 fetuses with chromosomal abnormalities, 19 (54.3%) were trisomy 18. CONCLUSION: Chromosomal abnormalities occurred in 43.2% of CHD cases and trisomy 18 is the most common aneuploidy. The likelihood of chromosomal anomaly increases when there is extracardiac involvement. Testing for the 22q11.2 microdeletion/duplication is recommended in all CHD fetuses without chromosomal anomalies. It is important for the further management of pregnancy and genetic counseling.