Application of non-invasive prenatal testing for the screening of fetal chromosomal abnormalities in 12 085 cases / 中华医学遗传学杂志

OBJECTIVE@#To assess the value of non-invasive prenatal testing (NIPT) for the screening of fetal chromosomal abnormalities.@*METHODS@#For 12 085 pregnant women, the results of NIPT and invasive prenatal diagnosis were compared.@*RESULTS@#The test was successful in 12 067 cases and has detected 179 chromosomal abnormalities, with a positive rate of 1.48%, sensitivity of 98.39% and specificity of 99.02%. Invasive prenatal diagnosis was performed for 3 of 18 patients who had failed NIPT but has detected no karyotypic abnormality. Except for one case of twin Cesarean section which delivered a normal female fetus and a stillbirth of unknown sex, the remainder of the 18 cases all had a normal delivery. The positive rate of NIPT screening for the abnormal ultrasound group was significant higher than that other groups (P< 0.01). Among those with positive results of NIPT, 122 underwent invasive prenatal diagnosis, and 25 trisomy 21, 7 trisomy 18, 3 trisomy 13, 4 aneuploidies of other autosomes, 13 sex chromosomal aneuploidies and 9 microdeletion/microduplications were confirmed, which yielded a positive predictive rate of 86.21%, 50.00%, 23.08%, 21.05%, 46.43%, and 47.36%, respectively.@*CONCLUSION@#NIPT has high sensitivity, specificity and positive predictive value, and is an effective method for prenatal screening. In addition to chromosomes 21, 18 and 13, NIPT has certain predictive value for other autosomal aneuploidies, sex chromosomal aneuploidies, microdeletion/microduplications, and can provide a reference for karyotype analysis and chromosomal microarray verification.

Prenatal diagnosis of a fetus with Phelan-McDermid syndrome and 21q21 microdeletion by multiple genetic techniques / 中华医学遗传学杂志

OBJECTIVE@#To carry out prenatal diagnose for a fetus with ultrasonography abnormalities using multiple genetic techniques.@*METHODS@#Routine G-banding chromosomal analysis and single nucleotide polymorphism array (SNP-array) were applied in conjunction for the prenatal diagnosis of the fetus. The result was confirmed by fluorescence in situ hybridization (FISH).@*RESULTS@#SNP-array detected that the fetus has carried a hemizygous 5.1 Mb deletion at 22q13.31q13.33, which is associated with Phelan-McDermid syndrome, and a hemizygous 4.5 Mb deletion at 21q21.1q21.2. FISH analysis of the fetus and its parents suggested that both deletions were de novo in origin.@*CONCLUSION@#The hemizygous deletions on 21q21.1q21.2 and 22q13.31q13.33 probably underlay the abnormal phenotype of the fetus. Genetic analysis can provide crucial information for the prenatal diagnosis and genetic counseling.

Prenatal diagnosis of a tetrasomy 18p case using BACs-on-Beads technology and single nucleotide polymorphism array / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To determine the origin of a supernumerary small marker chromosome found in a fetus using prenatal BACs-on-Beads (BoBs) and single nucleotide polymorphism array (SNP-array) assays.</p><p><b>METHODS</b>The fetal sample was subjected to chromosomal karyotyping and BoBs analysis, and the results were validated with genome-wide scanning using a SNP microarray.</p><p><b>RESULTS</b>The fetus was found to have a 47,XX,+mar karyotype. BoBs analysis indicated that there was an amplification between 18p11.32 and 18p11.21, which was verified by the SNP-array assay as a 18.3 Mb duplication occurring at 18p11.32q11.1.</p><p><b>CONCLUSION</b>The karyotype of the fetus was determined as 47,XX,+der18(18p11.32?18q11.1::18q11.1?18p11.32). The duplication has involved important genes including SMCHD1, LPIN2 and TGIF1, which may result in severe malformations in the fetus.</p>

A case of Wolf-Hirschhorn syndrome diagnosed by single nucleotide polymorphism array / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genetic causes for a child with multiple congenital malformations and epilepsy through analysis of copy number variations, and to correlate the genotype with the phenotype.</p><p><b>METHODS</b>G-banding karyotyping was performed on the child and her parents. Single nucleotide polymorphisms array (SNP-array) was used to map the exact chromosomal breakpoints in the proband. The result was validated with fluorescence in situ hybridization (FISH).</p><p><b>RESULTS</b>G banding analysis suggested that the proband had a karyotype of 46,XX,del(4)(p15), while both of his parents had a normal karyotype. SNP-array has identified a hemizygous deletion of 13.3 Mb on chromosome 4p16.3p15.33, which has been implicated in Wolf-Hirschhorn syndrome. FISH assay has confirmed the de novo origin of the deletion, with the karyotype and clinical phenotype of both parents taken into consideration.</p><p><b>CONCLUSION</b>A case of Wolf-Hirschhorn syndrome has been diagnosed by clinical manifestation and karyotyping analysis. Compared with conventional karyotyping analysis, SNP-array has greater resolution and accuracy, and can provide useful information for genetic counseling.</p>

Prenatal diagnosis of a Pallister-Killian syndrome case through analysis of a supernumerary chromosome using single nucleotide polymorphism array / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the origin of a supernumerary small marker chromosome (sSMC) in a fetus, and to assess the feasibility of single nucleotide polymorphism array (SNP-array) for prenatal diagnosis.</p><p><b>METHODS</b>The fetal sample was subjected to karyotyping analysis. The identified sSMC was subjected to genome-wide scan using a SNP microarray chip. The results were validated with fluorescence in situ hybridization (FISH).</p><p><b>RESULTS</b>The karyotype of the fetus was determined as 47,XX,+mar, which was verified by SNP microarray chip analysis as a 34.6 Mb duplication in 12p13.33p11.1. FISH analysis confirmed that the sSMC has originated from chromosome 12p.</p><p><b>CONCLUSION</b>The karyotype of the fetus was determined as 47,XX,+i(12)(p10). Tetrasomy 12p is reported to be a marker for Pallister-Killian syndrome, which may result in multi-system anomalies. SNP-array analysis can simultaneously detect microdeletions and microduplications, which may be used for prenatal diagnosis of suspected cases.</p>

Diagnosis of a case with Williams-Beuren syndrome by single nucleotide polymorphism array / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore the genetic cause for a child with mental retardation, developmental delay and multi-systemic developmental disorders by analyzing the copy number variations (CNVs) and correlating the genotype with the phenotype.</p><p><b>METHODS</b>Routine G-banding was performed to analyze the karyotype of the patient and her parents. In addition, single nucleotide polymorphisms array (SNP-array) was used to determine the CNVs, which was confirmed by fluorescence in situ hybridization (FISH).</p><p><b>RESULTS</b>No karyotypic abnormality was detected upon chromosome analysis. However, SNP-array has identified a de novo hemizygous deletion of 1673 kb on chromosome region 7q11.23, which has been associated with Williams-Beuren syndrome. The microdeletion was confirmed by FISH testing.</p><p><b>CONCLUSION</b>A child with Williams-Beuren syndrome has been diagnosed by SNP-array and FISH. The de novo 7q11.23 microdeletion probably underlies the clinical manifestation of the patient. Compared with routine karyotype analysis, SNP-array is more useful for diagnosing children with multiple congenital anomalies with unclear etiology.</p>