The genetic landscape of chromosomal aberrations in 3776 Vietnamese fetuses with clinical anomalies during pregnancy.

Background: Copy number variation sequencing (CNV-seq) is a powerful tool to discover structural genomic variation, but limitations associated with its retrospective study design and inadequate diversity of participants can be impractical for clinical application. Aim: This study aims to use CNV-seq to assess chromosomal aberrations in pregnant Vietnamese women. Materials & methods: A large-scale study was conducted on 3776 pregnant Vietnamese women with abnormal ultrasound findings. Results: Chromosomal aberrations were found in 448 (11.86%) women. Of these, 274 (7.26%) had chromosomal aneuploidies and 174 (4.61%) carried pathogenic/likely pathogenic CNVs. Correlations were established between chromosomal aberrations and various phenotypic markers. Conclusion: This comprehensive clinical study illuminates the pivotal role of CNV-seq in prenatal diagnosis for pregnancies featuring fetal ultrasound anomalies.

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Prevalence of Thalassemia in the Vietnamese Population and Building a Clinical Decision Support System for Prenatal Screening for Thalassemia.

Introduction: The prevalence of thalassemia among the Vietnamese population was studied, and clinical decision support systems for prenatal screening of thalassemia were created. The aim of this report was to investigate the prevalence of thalassemia in the Vietnamese population, building a clinical decision support system for prenatal screening for thalassemia. Methods: A cross-sectional study was conducted on pregnant women and their husbands visiting the Vietnam National Hospital of Obstetrics and Gynecology from October 2020 to December 2021. A total of 10112 medical records of first-time pregnant women and their husbands were collected. Results: A clinical decision support system was built, including 2 different types of systems for prenatal screening for thalassemia (an expert system and 4 AI-based CDSS). One thousand nine hundred ninety-two cases were used to train and test machine learning models, while 1555 cases were used for specialized expert system evaluation. There were ten key variables for AI-based CDSS for machine learning. The four most important features in thalassemia screening were identified. The accuracy of the expert system and AI-based CDSS was compared. The rate of patients with Alpha thalassemia is 10.73% (1085 patients), the rate of patients with beta-thalassemia is 2.24% (227 patients), and 0.29% (29 patients) of patients carry both alpha-thalassemia and beta-thalassemia gene mutations. The expert system showed an accuracy of 98.45%. Among the AI-based CDSS developed, the multilayer perceptron (MLP) model was the most stable regardless of the training database (accuracy of 98,5% using all features and 97% using only the four most important features). Conclusions: When comparing the expert system with the AI-based CDSS, the accuracy of the expert system and AI-based models was comparable. The developed expert system for prenatal thalassemia screening showed high accuracy. AI-based CDSS showed satisfactory results. Further development of such systems is promising with a view to their introduction into clinical practice.

High prevalence of maternal mosaic monosomy X in pregnant women in Vietnam.

OBJECTIVE: To demonstrate the prevalence of maternal mosaic monosomy X (MMXO) in a cohort of pregnant women in Vietnam. METHODS: All 105,594 singleton pregnant women undergoing noninvasive prenatal screening (NIPS) between January 2019 and February 2021 in Vietnam were analyzed by measuring discordance between size- and count-based z-scores for chromosome X (ChrX) to identify suspected cases of MMXO and validated by fluorescence in situ hybridization (FISH) on maternal blood. RESULTS: We identified 295 (0.279%) suspected MMXO cases. After FISH analysis, MMXO was confirmed in 125 cases (42.37%), revealing the MMXO prevalence of 0.118% (95% CI: 0.097-0.139%) in this cohort. CONCLUSION: We found a relatively high prevalence of MMXO in Vietnamese pregnant women and demonstrated a strong influence of MMXO on the ChrX z-score using a count-based method, resulting in false positives. The size-based method is not sensitive to MMXO and therefore achieves higher PPV.

Developing and validating noninvasive prenatal testing for de novo autosomal dominant monogenic diseases in Vietnam.

Background: Over 60% of single-gene diseases in newborns are autosomal dominant variants. Noninvasive prenatal testing for monogenic conditions (NIPT-SGG) is cost-effective and timesaving, but not widely applied. This study introduces and validates NIPT-SGG in detecting 25 monogenic conditions. Methods: NIPT-SGG with a 30-gene panel applied next-generation sequencing and trio assays to confirm de novo variants. Diagnostic tests confirmed NIPT-detected cases. Results: Among 93 pregnancies with ultrasound findings, 11 (11.8%) fetuses were screened and diagnosed with monogenic diseases, mostly with Noonan syndrome. NIPT-SGG determined >99.99% of actual positive and negative cases, confirmed by diagnostic tests. No false-negatives or false-positives were reported. Conclusion: NIPT-SGG effectively identifies the fetuses affected with monogenic diseases, which is a promisingly safe and timely antenatal screening option for high-risk pregnancies.

De novo variants of dominant monogenic disorders in Vietnam detected by a noninvasive prenatal test: a case series.

Background: Noninvasive prenatal tests for monogenic diseases (NIPT-SGG) have recently been reported as helpful in early-stage antenatal screening. Our study describes the clinical and genetic features of cases identified by NIPT-SGG. Materials & methods: In a cohort pregnancy with abnormal sonograms, affected cases were confirmed by invasive diagnostic tests concurrently, with NIPT-SGG targeting 25 common dominant single-gene diseases. Results: A total of 13 single-gene fetuses were confirmed, including Noonan and Costello syndromes, thanatophoric dysplasia, achondroplasia, osteogenesis imperfecta and Apert syndrome. Two novel variants seen were tuberous sclerosis complex (TSC2 c.4154G>A) and Alagille syndrome (JAG1 c.3452del). Conclusion: NIPT-SGG and standard tests agree on the results for 13 fetuses with monogenic disorders. This panel method of screening can benefit high-risk Vietnamese pregnancies, but further research is encouraged to expand on the causative gene panel.