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Fulltext A rare case of trisomy 8 mosaicism syndrome in a Malay boy

Vengidasan, Lelamekala, Siti Fatimah Ramli, Abdul Rahman Azhari, Narazah Mohd Yusoff, Nurul Hidayah Ruslan

Journal of Biomedical and Clinical Sciences, 2016;1(1):9-11.
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Trisomy 8 is a condition where every cell of an individual presents with an extra copy (three copies of chromosome 8. This disorder occurs when a pair of chromosomes fails to divide evenly, which results in cells containing more than two of this chromosome. Here, we report a case of mosaic trisomy 8 in a Malaysian Malay boy.Although patient in this case confirmed with T8M, he exhibited few of the characteristic features that previously were reported to be associated with T8M. However, the patient’s very young age might explain the lack of clinical presentation of these features.
Microfluidic chip-based assay for post-hematopoietic stem cell transplantation chimerism monitoring using polymorphic tandem repeat markers

Daud SS, Ibrahim K, Choong SS, Vengidasan L, Chong LA, Ariffin H

Anal Biochem, 2010 Feb 15;397(2):181-5.
PMID: 19822126 DOI: 10.1016/j.ab.2009.10.008

Following hematopoietic stem cell transplantation (HSCT), it is important to determine whether engraftment is successful and to track the dynamic changes of the graft. Tandem repeats such as minisatellites and microsatellites are currently the most established markers for chimerism application. We have developed a reliable method to quantitatively evaluate engraftment status in post-allogeneic HSCT patients using variable number of tandem repeat (VNTR) markers and "lab-on-a-chip" microfluidic electrophoresis technology. Following identification of an informative marker by conventional polymerase chain reaction (PCR), donor chimerism percentage was calculated based on a standard curve generated from artificially mixed patient-donor DNA-specific alleles in serial dilutions. All PCR products were mixed with commercial gel dye and loaded into Agilent DNA 1000 microfluidic LabChips for DNA sizing and quantitation. In 44 patients, separation of pretransplant and donor DNA fragments was resolved clearly and accomplished rapidly within 30min. Chimerism analysis using this platform is able to detect an amount as low as 6.3% donor DNA with acceptable coefficient of variation values. We also demonstrated concordant chimerism analysis findings using both microchip tandem repeats and real-time PCR quantitation of insertion-deletion polymorphisms. This microchip platform obviates the need for fluorescently labeled primers or any post-PCR sample manipulation. Quantitative monitoring of post-HSCT chimerism status using microfluidic electrophoresis is a useful tool for both large- and small-scale post-HSCT chimerism centers.
Fulltext Production and differential activity of recombinant human wild-type G6PD and G6PDViangchan

Vengidasan L, Yunus MA, Yusoff NM, Yahaya BH, Ismail IS

Asian Biomed (Res Rev News), 2020 Aug;14(4):159-167.
PMID: 37551388 DOI: 10.1515/abm-2020-0023

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) is essential to produce reduced nicotinamide adenine dinucleotide phosphate, which is required to protect cells against oxidative stress. G6PD deficiency is a genetic variation that may lead to hemolysis with potential consequences, such as kidney failure, and patients often experience low quality of life.
OBJECTIVES: To establish a simple, efficient, and optimized method to produce a G6PDViangchan variant and characterize the phenotypes of recombinant human wild-type G6PD and G6PDViangchan.
METHODS: G6PD was amplified by polymerase chain reaction (PCR) from a human cDNA plasmid, and the gene for G6PDViangchan was amplified by initiating a mutation at location 871 (G>A) through site-directed mutagenesis. Protein expression and western blotting were conducted after successful cloning. The enzymatic activity of both proteins was assessed spectrophotometrically after purification.
RESULTS: Both amplicons were successfully cloned into a pET26b(+) expression vector and transformed into Escherichia coli BL21 (DE3) cells for overexpression as C-terminally histidine-tagged recombinant proteins. Western blotting confirmed that both proteins were successfully produced at similar levels. The enzymes were purified by immobilized metal (Co) affinity chromatography. Postpurification assay of enzyme activity revealed about 2-fold differences in the levels of specific activity between the wild-type G6PD (155.88 U/mg) and G6PDViangchan (81.85 U/mg), which is consistent with earlier reports. Analysis in silico showed that the coding change in G6PDViangchan has a substantial effect on protein folding structure.
CONCLUSIONS: We successfully cloned, expressed, and purified both wild-type G6PD and G6PDViangchan proteins. Such a protocol may be useful for creating a model system to study G6PD deficiency disease.

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