Combined Gap-Polymerase Chain Reaction and Targeted Next-Generation Sequencing Improve α- and ß-Thalassemia Carrier Screening in Pregnant Women in Vietnam.

Vietnam has a high thalassemia burden. We collected blood samples from 5880 pregnant Vietnamese women during prenatal health checks to assess thalassemia carrier frequency using combined gap-polymerase chain reaction (gap-PCR) and targeted next-generation sequencing (NGS). Thalassemia carriers were identified with prevalence of 13.13% (772), including 7.82% (460) carriers of α-thalassemia (α-thal), 5.31% (312) carriers of ß-thalassemia (ß-thal), and 0.63% (37) concurrent α-/ß-thal carriers. Deletional mutations (368) accounted for 80.0% of α-thal carriers, of which, --SEA (Southeast Asian) (n = 254; 55.0%) was most prevalent, followed by the -α3.7 (rightward) (n = 66; 14.0%) and -α4.2 (leftward) (n = 45; 9.8%) deletions. Hb Westmead (HBA2: c.369C>G) (n = 53) and Hb Constant Spring (Hb CS or HBA2: c.427T>C) (in 28) are the two most common nondeletional α-globin variants, accounting for 11.5 and 6.0% of α-thal carriers. We detected 11 different ß-thal genotypes. Hb E (HBB: c.79G>A) (in 211) accounted for 67.6% of ß-thal carriers. The most common ß-thal genotypes were associated with mutations at codon 17 (A>T) (HBB: c.52A>T), codons 41/42 (-TTCT) (HBB: c.126_129delCTTT), and codon 71/72 (+A) (HBB: c.217_218insA) (prevalence 0.70%, 0.68%, and 0.2%, respectively). Based on mutation frequencies calculated in this study, estimates of 5021 babies in Vietnam are affected with clinically severe thalassemia annually. Our data suggest a higher thalassemia carrier frequency in Vietnam than previously reported. We established that combining NGS with gap-PCR creates an effective large-scale thalassemia screening method that can detect a broad range of mutations.

Genetic landscape of recessive diseases in the Vietnamese population from large-scale clinical exome sequencing.

Accurate profiling of population-specific recessive diseases is essential for the design of cost-effective carrier screening programs. However, minority populations and ethnic groups, including Vietnamese, are still underrepresented in existing genetic studies. Here, we reported the first comprehensive study of recessive diseases in the Vietnamese population. Clinical exome sequencing data of 4503 disease-associated genes obtained from a cohort of 985 Vietnamese individuals was analyzed to identify pathogenic variants, associated diseases and their carrier frequencies in the population. A total of 118 recessive diseases associated with 164 pathogenic or likely pathogenic variants were identified, among which 28 diseases had carrier frequencies of at least 1% (1 in 100 individuals). Three diseases were prevalent in the Vietnamese population with carrier frequencies of 2-12 times higher than in the world populations, including beta-thalassemia (1 in 23), citrin deficiency (1 in 31), and phenylketonuria (1 in 40). Seven novel pathogenic and two likely pathogenic variants associated with nine recessive diseases were discovered. The comprehensive profile of recessive diseases identified in this study enables the design of cost-effective carrier screening programs specific to the Vietnamese population.

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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Phenyl glycosides from Bacopa monnieri with their antioxidant and anti-inflammatory activities.

Bacopa monnieri (L.) Wettst (Plantaginaceae), is traditionally used in many countries as neural tonic and memory enhancer, or to relieve acute pain and inflammation. This study described the isolation and identification of one new, bacomoside D3 (1), and seven known phenyl glycosides (2 - 8). The structures of isolates were established by analysis of their spectroscopic data or hydrolysis followed by HPLC analysis together with a comparison to those reported in the literature. These compounds were evaluated for antioxidant and anti-inflammatory activities. Among them, compounds 4 and 5 exhibited strong DPPH radical scavenging activity with IC50 values of 9.77 ± 0.08 and 3.50 ± 0.04 µM, respectively. Compounds 2 and 5 significantly inhibited TNF-α production in LPS-stimulated RAW264.7 cells with IC50 values of 40.60 ± 3.05 and 38.19 ± 1.75 µM, respectively. Furthermore, the active compounds could be efficient inhibitors of oxidants by interfering with the DPPH activity in silico study.

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.

Agallochin P, a new diterpene from Vietnamese mangrove Excoecaria agallocha L.

A new diterpene (1) along with eight known compounds (2-9) were isolated from Excoecaria agallocha leaves. The structure and relative configuration of new compound were established on the basis of spectroscopic data analysis and confirmed by NMR chemical shifts calculation with DP4+ probability. Cytotoxicity of the isolated compounds were also evaluated.[Formula: see text].

Detection of maternal carriers of common α-thalassemia deletions from cell-free DNA.

α-Thalassemia is a common inherited blood disorder manifested mainly by the deletions of α-globin genes. In geographical areas with high carrier frequencies, screening of α-thalassemia carrier state is therefore of vital importance. This study presents a novel method for identifying female carriers of common α-thalassemia deletions using samples routinely taken for non-invasive prenatal tests for screening of fetal chromosomal aneuploidies. A total of 68,885 Vietnamese pregnant women were recruited and α-thalassemia statuses were determined by gap-PCR, revealing 5344 women (7.76%) carried deletions including αα/--SEA (4.066%), αα/-α3.7 (2.934%), αα/-α4.2 (0.656%), and rare genotypes (0.102%). A two-stage model was built to predict these α-thalassemia deletions from targeted sequencing of the HBA gene cluster on maternal cfDNA. Our method achieved F1-scores of 97.14-99.55% for detecting the three common genotypes and 94.74% for detecting rare genotypes (-α3.7/-α4.2, αα/--THAI, -α3.7/--SEA, -α4.2/--SEA). Additionally, the positive predictive values were 100.00% for αα/αα, 99.29% for αα/--SEA, 94.87% for αα/-α3.7, and 96.51% for αα/-α4.2; and the negative predictive values were 97.63%, 99.99%, 99.99%, and 100.00%, respectively. As NIPT is increasingly adopted for pregnant women, utilizing cfDNA from NIPT to detect maternal carriers of common α-thalassemia deletions will be cost-effective and expand the benefits of NIPT.

Garcinoxanthones SV, new xanthone derivatives from the pericarps of Garcinia mangostana together with their cytotoxic and antioxidant activities.

Xanthones (9H-xanthene-9-ones) are considered to be very promising compounds due to a variety of interesting biological and pharmacological activities. In this study, column chromatography of the methanol extract of the Garcinia mangostana L. pericarps resulted in the isolation of four new xanthones (garcinoxanthones SV, 1-4) and five known analogs including garcinone E (5), 11-hydroxy-1-isomangostin (6) mangostenone E (7), 1,3,6,7-tetrahydroxyxanthone (8), and α-mangostin (9). The structures of the new compounds were elucidated by NMR, HRESIMS, and ECD spectra. Compound 8 (1,3,6,7-tetrahydroxyxanthone) was found from the G. mangostana pericarps for the first time. All the isolated compounds (1-8) were evaluated for their 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity and cytotoxicity in vitro against three human cancer cell lines including SK-LU-1, MCF7, and HT-29 cell lines. Compounds 3, 5, and 8 exhibited significant DPPH scavenging capacity with IC50 values of 68.55, 63.05, and 28.45 µM, respectively, in comparison with ascorbic acid (IC50 = 48.03 µM). Compounds 5 and 8 showed moderate cytotoxic effects against the three human cancer cell lines with IC50 value ranges of 19.86-27.38 µM.

Genetic profiling of Vietnamese population from large-scale genomic analysis of non-invasive prenatal testing data.

The under-representation of several ethnic groups in existing genetic databases and studies have undermined our understanding of the genetic variations and associated traits or diseases in many populations. Cost and technology limitations remain the challenges in performing large-scale genome sequencing projects in many developing countries, including Vietnam. As one of the most rapidly adopted genetic tests, non-invasive prenatal testing (NIPT) data offers an alternative untapped resource for genetic studies. Here we performed a large-scale genomic analysis of 2683 pregnant Vietnamese women using their NIPT data and identified a comprehensive set of 8,054,515 single-nucleotide polymorphisms, among which 8.2% were new to the Vietnamese population. Our study also revealed 24,487 disease-associated genetic variants and their allele frequency distribution, especially 5 pathogenic variants for prevalent genetic disorders in Vietnam. We also observed major discrepancies in the allele frequency distribution of disease-associated genetic variants between the Vietnamese and other populations, thus highlighting a need for genome-wide association studies dedicated to the Vietnamese population. The resulted database of Vietnamese genetic variants, their allele frequency distribution, and their associated diseases presents a valuable resource for future genetic studies.

Treatment of dementia and mild cognitive impairment with or without cerebrovascular disease: Expert consensus on the use of Ginkgo biloba extract, EGb 761®.

BACKGROUND: The Ginkgo biloba special extract, EGb 761® has been widely used in the treatment of neuropsychiatric disorders, including Alzheimer's disease (AD). METHODS: To guide clinical practice in the Asian region, the Asian Clinical Expert Group on Neurocognitive Disorders compiled evidence-based consensus recommendations regarding the use of EGb 761® in neurocognitive disorders with/without cerebrovascular disease. RESULTS: Key randomized trials and robust meta-analyses have demonstrated significant improvement in cognitive function, neuropsychiatric symptoms, activities of daily living (ADL) and quality of life with EGb 761® versus placebo in patients with mild-to-moderate dementia. In those with mild cognitive impairment (MCI), EGb 761® has also demonstrated significant symptomatic improvement versus placebo. World Federation of Societies of Biological Psychiatry guidelines list EGb 761® with the same strength of evidence as acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) antagonists e.g. memantine (Grade 3 recommendation; Level B evidence). Only EGb 761® had Level B evidence in improving cognition, behaviour, and ADL in both AD and vascular dementia patients. Safety analyses show EGb 761® to have a positive risk-benefit profile. While concerns have been raised regarding a possible increased bleeding risk, several randomized trials and two meta-analyses have not supported this association. CONCLUSIONS: The Expert Group foresee an important role for EGb 761® , used alone or as an add-on therapy, in the treatment of MCI and dementias, particularly when patients do not derive benefit from acetylcholinesterase inhibitors or NMDA antagonists. EGb 761® should be used in alignment with local clinical practice guidelines.