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Cytogenetic and molecular genetic analysis of three fetuses at high risk of trisomy-16 detected by cell-free fetal DNA testing / 中华围产医学杂志
Chinese Journal of Perinatal Medicine ; (12): 608-613, 2021.
Article in Chinese | WPRIM | ID: wpr-911939
ABSTRACT

Objective:

To investigate the power and prenatal diagnosis strategies of cell-free fetal DNA (cffDNA) testing for chromosomal aneuploidy screening apart from trisomy-13/18/21.

Methods:

This study collected the clinical data of three cases at high risk of trisomy-16 indicated by cffDNA testing in Hunan Provincial Maternal and Child Health Care Hospital from March 2019 to March 2020. Results of the conventional G-banding karyotype analysis of amniotic fluid, single nucleotide polymorphism array (SNP-array) and low-coverage massively parallel copy number variation sequencing (CNV-seq) of placenta/fetal skin samples were analyzed.

Results:

(1) cffDNA testing results suggested that case 1-3 were at high risk of trisomy-16 and the Z values of chromosome 16 were 20.57, 24.88 and 17.87, respectively. (2) Karyotype analysis of amniotic fluid samples did not identify any abnormalities in Case 1 and 2, while SNP-array revealed a 19.2 Mb and 23.0 Mb heterozygous deletion at 16p13.3p12.3 and 16q22.1q24.3 in Case 1, and a 16.0 Mb loss of heterozygosity at 16q22.3q24.3 in Case 2. Case 3 had a mosaicism karyotype of 47,XY,+16[3]/46,XY[97] and SNP-array analysis showed no heterozygous deletion greater than 5 Mb or copy number variation. (3) Ultrasonography indicated fetal growth restriction in Case 1 and 2 and fetal death in Case 3. All three pregnancies were terminated. CNV-seq analysis of placental tissue in the center of both fetal and maternal side revealed mosaic trisomy 16, with the copy numbers of chromosome 16 of 2.56/2.70, 2.73/2.82, 2.80/2.81, respectively. However, no copy number variation was detected in Case 1 or 2 by CNV-seq analysis of fetal skin tissues.

Conclusions:

cffDNA testing has a certain power in detecting trisomy-16 apart from trisomy-13/18/21. For high-risk cases of trisomy-16 indicated by cffDNA testing, SNP-array analysis combined with karyotype analysis is suggested to rule out low-level mosaicism and loss of heterozygosity.

Full text: Available Index: WPRIM (Western Pacific) Type of study: Etiology study Language: Chinese Journal: Chinese Journal of Perinatal Medicine Year: 2021 Type: Article

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Full text: Available Index: WPRIM (Western Pacific) Type of study: Etiology study Language: Chinese Journal: Chinese Journal of Perinatal Medicine Year: 2021 Type: Article