Molecular subtypes of Adenovirus-associated acute respiratory infection outbreak in children in Northern Vietnam and risk factors of more severe cases.

BACKGROUND: Under the pressure of Human Adenovirus (HAdV)-associated acute respiratory infection (ARI) outbreak in children in Northern Vietnam in the end of 2022, this study was initiated to identify the HAdV subtype(s) and examine the associated clinical features and risk factors of more severe cases. METHODS: This study evaluated pediatric patients with ARI which had tested positive for HAdV between October and November 2022 using a multiplex real-time PCR panel. Nasopharyngeal aspirates or nasal swab samples were used for sequencing to identify HAdV subtypes. Clinical data were collected retrospectively. RESULTS: Among 97 successfully sequenced samples, the predominant subtypes were HAdV-B3 (83%), HAdV-B7 (16%) and HAdV-C2 (1%). Lower respiratory manifestations were found in 25% of the patients of which 5% were diagnosed with severe pneumonia. There was no significant association between HAdV subtype and clinical features except higher white blood cell and neutrophil counts in those detected with HAdV-B3 (p<0.001). Co-detection of HAdV with ≥1 other respiratory viruses was found in 13/24(54%) of those with lower respiratory manifestations and 4/5(80%) of those with severe pneumonia (odds ratio (95% confidence interval) vs. those without = 10.74 (2.83, 48.17) and 19.44 (2.12, 492.73) respectively after adjusting for age, sex, birth delivery method, day of disease). CONCLUSION: HAdV-B3 and HAdV-B7 were predominant in the outbreak. Co-detection of HAdV together with other respiratory viruses was a strong risk factor for lower respiratory tract illnesses and severe pneumonia. The findings advocate the advantages of multi-factor microbial panels for the diagnosis and prognosis of ARI in children.

Clinical evaluation of RB1 genetic testing reveals novel mutations in Vietnamese patients with retinoblastoma.

Clinical evaluation of the genetic testing strategy is essential for ensuring the correct determination of mutation carriers. The current study retrospectively analyzed genetic and clinicopathological data from 62 Vietnamese patients with retinoblastoma (RB) referred to the Vinmec Hi-Tech Center for RB transcriptional corepressor 1 (RB1) genetic testing between 2017 and 2019. The present study aimed to evaluate the sensitivity of the Next Generation Sequencing (NGS) method to identify novel RB1 mutations, and to consider using age at diagnosis as a risk factor. Genomic DNA was analyzed with custom panel based targeted NGS. NGS was performed on the Beijing Genomics Institute (BGI) sequencing platform, and pathogenic or likely pathogenic variants were confirmed by Sanger sequencing, quantitative PCR (qPCR) or Multiplex Ligation-dependent Probe Amplification assay (MLPA). Constitutional RB1 variants were identified in 100% (25/25) of the bilateral cases, while several common previously reported RB1 mutations were also recorded. In addition, in Vietnamese patients with RB, nine novel RB1 mutations were identified. Children aged between 0-36 months were more likely to be RB1 carriers compared with those aged >36 months. The current findings indicated that the NGS method implemented in the Vinmec Hi-Tech Center was highly accurate, and age at diagnosis may be used to assess the risk of hereditary RB. Furthermore, the newly identified RB1 mutations may provide additional data to improve the current understanding of the mechanisms underlying RB1 inactivation and the development of rapid assays for detecting RB1 mutations. Overall, the present study suggested that NGS may be applied for detecting germline RB1 mutations in routine clinical practice.

Development of a new biochemical test to diagnose and monitor neuroblastoma in Vietnam: homovanillic and vanillylmandelic acid by gas chromatography-mass spectrometry.

OBJECTIVES: The aim of this study was to develop an accurate robust testing method to simultaneously measure urine levels of HVA and VMA using gas chromatography mass spectrometry (GCMS) and to establish age-specific reference intervals of HVA and VMA in random urines for Vietnamese children. DESIGN AND METHODS: The assay for urinary HVA and VMA was developed based on a classical urinary organic acid profiling method. Briefly, this incorporated 3-phenyl butyric acid as the internal standard and liquid-liquid extraction with ethyl acetate followed by derivatization with BSTFA. The Agilent 7890A GC and 5975C Mass Selective Detector in single ion monitoring mode was used for analysis. Reference intervals were developed from random urine samples collected from 634 disease free Vietnamese children and compared to 50 known neuroblastoma patient samples. Results were reported relative to creatinine concentration. Age related 95% reference intervals for urinary HVA and VMA were estimated from sample quantiles. The analytes (expressed as analyte/creatinine ratios) diagnostic values were determined by calculating the related sensitivity, specificity and likelihood ratios. RESULTS: HVA and VMA were linear to at least 193 and 221µmol/L, respectively. The limit of quantitation for both analytes was 0.9µmol/L. Using the bi-level control (n=15), the within-batch coefficients of variations (CVs) were less than 3% for both analytes across the assay range. The between-batch CVs (n=20 over three months), were 3.6% at 11µmol/L and 2.1% at 88µmol/L for HVA, 6.6% at 18.2µmol/L and 2.6% at 90.6µmol/L for VMA. Vietnamese age related reference intervals were established for urinary HVA and VMA per creatinine. HVA for children <6months (n=91) was 5.3-37.0µmol/mmol; 6months to <1year (n=141) was 2.7-27.7µmol/mmol; 1 to 5years (n=139) was 3.4-17.9µmol/mmol; 6 to 10years (n=136) was 2.7-8.8µmol/mmol; and 11 to 15years (n=127) was 1.1-9.4µmol/mmol. VMA for children <6months was 1.8-12.2µmol/mmol; 6months to <1year was 1.5-9.3µmol/mmol; 1 to 5years was 1.9-7.8µmol/mmol; 6 to 10years was 1.6-5.1µmol/mmol; and 11 to 15years was <0.9-6.3µmol/mmol. CONCLUSIONS: A robust testing method for simultaneous quantitation of urinary HVA and VMA by GCMS was developed. This method is accurate, precise and fit for its clinical purpose and suitable for developing countries. Age-related reference intervals of urinary HVA and VMA were established for Vietnamese children and the intervals declined progressively with increasing age for each analyte.