Prevalence of common autosomal recessive mutation carriers in women in the Southern Vietnam following the application of expanded carrier screening.

The common autosomal recessive (AR) mutation carrier is still unknown in Vietnam. This study aims to identify the most common AR gene mutation carriers in women of reproductive age to build a Vietnamese-specific carrier screening panel for AR and X-linked disorders in the preconception and prenatal healthcare program. A cross-sectional study was conducted at University Medical Center-Branch 2 in Ho Chi Minh City from December 1st, 2020, to June 30th, 2023. 338 women have consented to take a 5 mL blood test to identify 540 recessive genes. The carrier screening panel was designed based on the American College of Medical Genetics and Genomics (ACMG)-recommended genes and suggestions from 104 clinical experts in Vietnam. Obstetricians and genetic experts counseled all positive testing results to discuss the possibility of recessive diseases in their offspring. The most common recessive disorders were defined at a prevalence of 1 in 60 or greater, and those were added to a Vietnamese-specific carrier screening panel. 338 non-pregnant and pregnant women underwent the expanded carrier screening (ECS). The carrier frequency was 63.6%, in which 215 women carried at least one AR gene mutation. GJB2 hearing impairment was identified as the most common chronic condition (1 in 5). The second most common AR disorder was beta-thalassemia (1 in 16), followed by cystic fibrosis (1 in 23), G6PD deficiency (1 in 28), Wilson's disease (1 in 31), Usher's syndrome (1 in 31), and glycogen storage disease (1 in 56). Seven common recessive genes were added in ethnic-based carrier screening. Women in the South of Vietnam have been carried for many recessive conditions at high frequency, such as hearing impairment, genetic anemia, and cystic fibrosis. It is necessary to implement a preconception and prenatal screening program by using seven widely popular AR genes in a Vietnamese-specific carrier screening panel to reduce the burden related to AR and X-linked disorders.

Effect of Helicobacter pylori on non-homologous end joining-mediated repair of proximal DNA double-strand breaks in GCV6 cells.

Infection with Helicobacter pylori is the strongest known risk factor for gastric cancer, which is one of the leading causes of cancer-related mortality worldwide. H. pylori can contribute to carcinogenesis by inducing the genomic instability of infected cells through increasing accumulation of DNA double-stranded breaks (DSBs) and deregulating DSB repair systems. However, the mechanism of this phenomenon is still being elucidated. This study aims to investigate the impact of H. pylori on the efficacy of non-homologous end joining (NHEJ)-mediated repair of DSB. In this study, we used a human fibroblast cell line bearing a single copy of an NHEJ-reporter substrate stably inserted into the genome, which provides a quantitative measurement of NHEJ. Our results indicated the potential abilities of H. pylori strains to alter the NHEJ-mediated repair of proximal DSB in infected cells. In addition, we found an association between the alteration in the NHEJ efficiency, and the inflammation responses of infected cells caused by H. pylori.

Sweet Wormwood and Tortoise Shell Decoction (Thanh Hao Miet Giap Thang) Induces DNA Damage, S-Phase Arrest, and Apoptosis in MCF-7 Cells via ATR-CHK1 Signaling Pathway.

Introduction: Sweet wormwood and tortoise shell decoction, Thanh Hao Miet Giap Thang (THMGT) in Vietnamese, a traditional formula composed of five ingredients, is used in complementary care in Vietnam for patients who underwent conventional cancer treatment. To expand the clinical use and explore novel functions of THMGT, this study was conducted to investigate the effect of THMGT in terms of antiproliferative activity and selective cytotoxicity toward human breast cancer cells MCF-7. Methods: Cytotoxicity of THMGT against human breast cancer cells MCF-7 and primary fibroblasts from a heathy donor were studied using sulforhodamine B (SRB) assay. Flow cytometry analysis, immunofluorescence, and western blotting were also performed to elucidate underlying mechanisms of THMGT action. Results: The SRB assay on treated MCF-7 cells and primary fibroblasts from a heathy donor indicated selective cytotoxicity of THMGT with a selective index of 3.92. Annexin V/PI staining and flow cytometric analysis on stained MCF-7 cells showed that the THMGT-treated cells were arrested at the S phase and subsequently underwent apoptosis. Western blot analysis showed an upregulation of γ-H2AX, increased protein levels of phosphorylated CHK1, TP53, and phosphorylated TP53 in a time-dependent manner, and a downregulated expression of ATR and MDM2. Conclusion: These results suggested DNA damaging effect and ATR-CHK1-mediated cell cycle arrest of THMGT on MCF-7 cells resulting in apoptosis induction.

The endemic Helicobacter pylori population in Southern Vietnam has both South East Asian and European origins.

BACKGROUND: The burden of Helicobacter pylori-induced gastric cancer varies based on predominant H. pylori population in various geographical regions. Vietnam is a high H. pylori burden country with the highest age-standardized incidence rate of gastric cancer (16.3 cases/100,000 for both sexes) in Southeast Asia, despite this data on the H. pylori population is scanty. We examined the global context of the endemic H. pylori population in Vietnam and present a contextual and comparative genomics analysis of 83 H. pylori isolates from patients in Vietnam. RESULTS: There are at least two major H. pylori populations are circulating in symptomatic Vietnamese patients. The majority of the isolates (~ 80%, 66/83) belong to the hspEastAsia and the remaining belong to hpEurope population (~ 20%, 17/83). In total, 66 isolates (66/83) were cagA positive, 64 were hspEastAsia isolates and two were hpEurope isolates. Examination of the second repeat region revealed that most of the cagA genes were ABD type (63/66; 61 were hspEastAsia isolates and two were hpEurope isolates). The remaining three isolates (all from hspEastAsia isolates) were ABC or ABCC types. We also detected that 4.5% (3/66) cagA gene from hspEastAsia isolates contained EPIYA-like sequences, ESIYA at EPIYA-B segments. Analysis of the vacA allelic type revealed 98.8% (82/83) and 41% (34/83) of the strains harboured the s1 and m1 allelic variant, respectively; 34/83 carried both s1m1 alleles. The most frequent genotypes among the cagA positive isolates were vacA s1m1/cagA + and vacA s1m2/cagA + , accounting for 51.5% (34/66) and 48.5% (32/66) of the isolates, respectively. CONCLUSIONS: There are two predominant lineages of H. pylori circulating in Vietnam; most of the isolates belong to the hspEastAsia population. The hpEurope population is further divided into two smaller clusters.

V(D)J recombination process and the Pre-B to immature B-cells transition are altered in Fanca-/- mice.

B-lymphocytes in the bone marrow (BM) must generate a functional B-cell receptor and overcome the negative selection induced by reactivity with autoantigens. Two rounds of DNA recombination are required for the production of functional immunoglobulin heavy (Ig-HCs) and light (LCs) chains necessary for the continuation of B-lymphocyte development in the BM. Both rounds depend on the joint action of recombination activating gene-1 (RAG-1) and RAG-2 endonucleases with the DNA non-homologous end-joining pathway. Loss of the FANC gene leads to the chromosome breakage and cancer predisposition syndrome Fanconi anemia. Because the FANC proteins are involved in certain aspects of the recombination process, we sought to determine the impact of the FANC pathway on the Ig diversification process using Fanca-/- mice. In this work we demonstrated that Fanca-/- animals have a mild B-cell differentiation defect characterized by a specific alteration of the IgM- to IgM+ transition of the B220low B-cell population. Pre-B cells from Fanca-/- mice show evidence of impaired kLC rearrangement at the level of the Vk-Jk junction. Furthermore, Fanca-/- mice showed a skewed Vκ gene usage during formation of the LCs Vk-Jk junctions. Therefore, the Fanca protein appears as a yet unidentified factor involved in the primary diversification of Ig.

Fanca deficiency reduces A/T transitions in somatic hypermutation and alters class switch recombination junctions in mouse B cells.

Fanconi anemia is a rare genetic disorder that can lead to bone marrow failure, congenital abnormalities, and increased risk for leukemia and cancer. Cells with loss-of-function mutations in the FANC pathway are characterized by chromosome fragility, altered mutability, and abnormal regulation of the nonhomologous end-joining (NHEJ) pathway. Somatic hypermutation (SHM) and immunoglobulin (Ig) class switch recombination (CSR) enable B cells to produce high-affinity antibodies of various isotypes. Both processes are initiated after the generation of dG:dU mismatches by activation-induced cytidine deaminase. Whereas SHM involves an error-prone repair process that introduces novel point mutations into the Ig gene, the mismatches generated during CSR are processed to create double-stranded breaks (DSBs) in DNA, which are then repaired by the NHEJ pathway. As several lines of evidence suggest a possible role for the FANC pathway in SHM and CSR, we analyzed both processes in B cells derived from Fanca(-/-) mice. Here we show that Fanca is required for the induction of transition mutations at A/T residues during SHM and that despite globally normal CSR function in splenic B cells, Fanca is required during CSR to stabilize duplexes between pairs of short microhomology regions, thereby impeding short-range recombination downstream of DSB formation.