Objectives To compare the performance of traditional G-banding karyotyping with that of copy number variation sequencing (CNV-Seq

The Kagami–Ogata syndrome (KOS) is a rare imprinting disorder with a distinct clinical phenotype. In KOS, polyhydramnios is associated with a small bell-shaped thorax and coat-hanger ribs. The genetic etiology of KOS includes paternal uniparental disomy 14 [upd(14)pat], epimutations, and microdeletions affecting the maternally derived imprinted region of chromosome 14q32.2. More than 77 cases of KOS have been reported; however, only one mosaic upd(14)pat case has been reported. Here we report a second mosaic upd(14)pat case. The prognosis of upd(14)pat patients is poor because of severe respiratory insufficiency. We summarized prenatal ultrasound findings of KOS to raise awareness of this condition for possible diagnosis of KOS prenatally when polyhydramnios combination with a small bell-shaped thorax and other related features are first observed. Prenatal diagnosis using methylation-specific multiplex ligation-dependent probe amplification (MLPA) or a single-nucleotide polymorphism-based microarray analysis is recommended.

Objective: Since 2011, noninvasive prenatal testing (NIPT) has undergone rapid expansion with both utilization and coverage. However, conclusive data regarding the clinical validity and utility of this testing tool, have lagged behind. Thus, there is a continued need to educate clinicians and patients about the current benefits and limitations to inform pre- and posttest counseling, pre/perinatal decision making, and medical risk assessment/management.Methods: A retrospective study among women referred for invasive prenatal diagnosis to confirm positive NIPT results between January 2017 and December 2020. Prenatal diagnosis testing were taken including karyotype, chromosomal microarray analysis (CMA) or CNV-seq. Positive predictive values (PPV) were calculated.Results: A total of 468 women were recruited. The PPVs for trisomy 21, 18, 13 were 86.1%, 57.8%, 25.0%, respectively. The PPV for RCAs and CNVs were 17.0%, 40.4% respectively. Detection of SCAs had PPV of 20% for monosomy X, 23.5% for 47,XXX, 68.8% for 47,XXY and 62.5% for 47,XYY. High-risk groups had a significant increase in the number of true positive cases compared to the low and moderate risk groups.Conclusion: T13, Monosomy X, RCA are associated with lower PPVs. Improvement of the cell-free fetal DNA screening technology and continued monitoring of its performance is important.