Displaying publications 1 - 20 of 38 in total

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  1. Fulltext Rare homozygous PRKN exon 8 and 9 deletion in Malay familial early-onset Parkinson's disease
    Tay YW, Lim JL, Tan AH, Annuar AA, Lim SY
    Ann Acad Med Singap, 2021 04;50(4):353-355.
    PMID: 33990826 DOI: 10.47102/annals-acadmedsg.2020508
    Matched MeSH terms: Exons/genetics
  2. Choice of PCR microtube can impact on the success of long-range PCRs
    Chua EW, Miller AL, Kennedy MA
    Anal Biochem, 2015 May 15;477:115-7.
    PMID: 25766577 DOI: 10.1016/j.ab.2015.02.023
    We compared four brands of microtubes with respect to their suitability for long-range polymerase chain reactions (PCRs). One of the four brands was found to have an inhibitory effect, decreasing PCR yields. The effect was universal across different PCR or enzyme systems. Increased ultraviolet absorbance suggests leaching of unknown chemical species into PCR mixtures. However, this could not be confirmed by high-performance liquid chromatography-mass spectrometry analysis. Nevertheless, our article demonstrates a clear impact of the choice of microtubes on long-range PCR success. Due consideration should be given to the PCR microtubes when determining optimal reaction conditions for long-range PCR.
    Matched MeSH terms: Exons/genetics
  3. Fulltext Biological impact of mutually exclusive exon switching
    Lam SD, Babu MM, Lees J, Orengo CA
    PLoS Comput Biol, 2021 03;17(3):e1008708.
    PMID: 33651795 DOI: 10.1371/journal.pcbi.1008708
    Alternative splicing can expand the diversity of proteomes. Homologous mutually exclusive exons (MXEs) originate from the same ancestral exon and result in polypeptides with similar structural properties but altered sequence. Why would some genes switch homologous exons and what are their biological impact? Here, we analyse the extent of sequence, structural and functional variability in MXEs and report the first large scale, structure-based analysis of the biological impact of MXE events from different genomes. MXE-specific residues tend to map to single domains, are highly enriched in surface exposed residues and cluster at or near protein functional sites. Thus, MXE events are likely to maintain the protein fold, but alter specificity and selectivity of protein function. This comprehensive resource of MXE events and their annotations is available at: http://gene3d.biochem.ucl.ac.uk/mxemod/. These findings highlight how small, but significant changes at critical positions on a protein surface are exploited in evolution to alter function.
    Matched MeSH terms: Exons/genetics*
  4. Identification of a recurrent BRCA1 exon 21-22 genomic rearrangement in Malay breast cancer patients
    Hasmad HN, Sivanandan K, Lee V, Yip CH, Mohd Taib NA, Teo SH
    Clin Genet, 2015 Apr;87(4):392-4.
    PMID: 25066186 DOI: 10.1111/cge.12451
    Matched MeSH terms: Exons/genetics
  5. HLA-B*15:349:02, a novel variant of HLA-B*15, discovered in a Singaporean Malay bone marrow donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 09;96(3):344-345.
    PMID: 32212215 DOI: 10.1111/tan.13879
    One nucleotide substitution in codon 112 of HLA-B*15:349:01 results in a novel allele, HLA-B*15:349:02.
    Matched MeSH terms: Exons/genetics
  6. HLA-DQB1*06:132, an HLA-DQB1*06 variant, discovered in a Singaporean Malay bone marrow donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 08;96(2):243-244.
    PMID: 32250029 DOI: 10.1111/tan.13889
    One nucleotide substitution in codon 38 of HLA-DQB1*06:01:01:01 results in a novel allele, HLA-DQB1*06:132.
    Matched MeSH terms: Exons/genetics
  7. HLA-DQB1*05:66:01, a novel variant of HLA-DQB1*05, identified in a Singaporean Malay bone marrow donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 08;96(2):240-241.
    PMID: 32246584 DOI: 10.1111/tan.13887
    Nucleotide substitutions in codon 38 of HLA-DQB1*05:03:01:01 result in a novel allele, HLA-DQB1*05:66:01.
    Matched MeSH terms: Exons/genetics
  8. HLA-B*38:64, an HLA-B*38 variant, detected in a Singaporean Malay unrelated hematopoietic stem cell donor
    Cho L, Kaur A, Cereb N, Lin PY, Yang KL
    HLA, 2020 08;96(2):217-218.
    PMID: 32227685 DOI: 10.1111/tan.13873
    One nucleotide substitution in codon 89 of HLA-B*38:02:01:01 results in a novel allele, HLA-B*38:64.
    Matched MeSH terms: Exons/genetics
  9. Discovery of HLA-B*35:368, a novel HLA-B*35 variant, in a Singaporean Malay hematopoietic stem cell donor
    Kaur A, Cho L, Cereb N, Lin PY, Yang KL
    HLA, 2020 07;96(1):94-95.
    PMID: 32166893 DOI: 10.1111/tan.13862
    DNA substitutions from codons 69 to 71 of HLA-B*35:05:01:01 result in a novel allele, HLA-B*35:368.
    Matched MeSH terms: Exons/genetics
  10. Fulltext Improved ontology for eukaryotic single-exon coding sequences in biological databases
    Jorquera R, González C, Clausen P, Petersen B, Holmes DS
    Database (Oxford), 2018 01 01;2018:1-6.
    PMID: 30239665 DOI: 10.1093/database/bay089
    Efficient extraction of knowledge from biological data requires the development of structured vocabularies to unambiguously define biological terms. This paper proposes descriptions and definitions to disambiguate the term 'single-exon gene'. Eukaryotic Single-Exon Genes (SEGs) have been defined as genes that do not have introns in their protein coding sequences. They have been studied not only to determine their origin and evolution but also because their expression has been linked to several types of human cancer and neurological/developmental disorders and many exhibit tissue-specific transcription. Unfortunately, the term 'SEGs' is rife with ambiguity, leading to biological misinterpretations. In the classic definition, no distinction is made between SEGs that harbor introns in their untranslated regions (UTRs) versus those without. This distinction is important to make because the presence of introns in UTRs affects transcriptional regulation and post-transcriptional processing of the mRNA. In addition, recent whole-transcriptome shotgun sequencing has led to the discovery of many examples of single-exon mRNAs that arise from alternative splicing of multi-exon genes, these single-exon isoforms are being confused with SEGs despite their clearly different origin. The increasing expansion of RNA-seq datasets makes it imperative to distinguish the different SEG types before annotation errors become indelibly propagated in biological databases. This paper develops a structured vocabulary for their disambiguation, allowing a major reassessment of their evolutionary trajectories, regulation, RNA processing and transport, and provides the opportunity to improve the detection of gene associations with disorders including cancers, neurological and developmental diseases.
    Matched MeSH terms: Exons/genetics*
  11. Sequencing analysis of exons 5 and 6 in RUNX2 in non-syndromic patients with supernumerary tooth in Kelantan, Malaysia
    Saharudin S, Sanusi SY, Ponnuraj KT
    Clin Oral Investig, 2022 Feb;26(2):1261-1268.
    PMID: 34453594 DOI: 10.1007/s00784-021-04098-x
    OBJECTIVE: The aim of this study is to do a sequencing analysis of RUNX2 in non-syndromic patients with supernumerary tooth.

    MATERIALS AND METHODS: Fifty-three patients with supernumerary tooth were identified retrospectively from 1,275 radiographic reviews who attended the Hospital Universiti Sains Malaysia (USM) Dental Clinic. Informed consent was obtained from the patients prior to the study. Blood samples were collected from 41 patients and DNA extractions were performed out of which 10 samples were chosen randomly for PCR amplification using designated primers for RUNX2 followed by DNA sequencing analysis.

    RESULTS: This study involved 28 male patients (68.3%) and 13 female patients (31.7%) with a gender ratio of 2.2:1 and mean age of 15.9 ± 6.2 years. DNA extraction yielded ~ 40 ng/μl of concentrated DNA, and each DNA sample had more than 1500 bp of DNA length. The purity ranged between 1.8 and 2.0. DNA sequencing analysis did not reveal any mutations in exons 5 and 6 of RUNX2.

    CONCLUSION: This study did not reveal any mutations in exons 5 and 6 of RUNX2 in non-syndromic patients with supernumerary tooth.

    CLINICAL RELEVANCE: Analysis of mutations in RUNX2 is important to enhance the understanding of tooth development in humans.

    Matched MeSH terms: Exons/genetics
  12. Fulltext Identification and characterization of a novel Epstein-Barr Virus-encoded circular RNA from LMP-2 Gene
    Tan KE, Ng WL, Marinov GK, Yu KH, Tan LP, Liau ES, et al.
    Sci Rep, 2021 Jul 13;11(1):14392.
    PMID: 34257379 DOI: 10.1038/s41598-021-93781-w
    Epstein-Barr virus (EBV) has been recently found to generate novel circular RNAs (circRNAs) through backsplicing. However, comprehensive catalogs of EBV circRNAs in other cell lines and their functional characterization are still lacking. In this study, we have identified a list of putative EBV circRNAs in GM12878, an EBV-transformed lymphoblastoid cell line, with a significant majority encoded from the EBV latent genes. A novel EBV circRNA derived from the exon 5 of LMP-2 gene which exhibited highest prevalence, was further validated using RNase R assay and Sanger sequencing. This circRNA, which we term circLMP-2_e5, can be universally detected in a panel of EBV-positive cell lines modelling different latency programs. It ranges from lower expression in nasopharyngeal carcinoma (NPC) cells to higher expression in B cells, and is localized to both the cytoplasm and the nucleus. We provide evidence that circLMP-2_e5 is expressed concomitantly with its cognate linear LMP-2 RNA upon EBV lytic reactivation, and may be produced as a result of exon skipping, with its circularization possibly occurring without the involvement of cis elements in the short flanking introns. Furthermore, we show that circLMP-2_e5 is not involved in regulating cell proliferation, host innate immune response, its linear parental transcripts, or EBV lytic reactivation. Taken together, our study expands the current repertoire of putative EBV circRNAs, broadens our understanding of the biology of EBV circRNAs, and lays the foundation for further investigation of their function in the EBV life cycle and disease development.
    Matched MeSH terms: Exons/genetics
  13. Co-inheritance of variants/mutations in Malaysian patients with Crohn's disease
    Chua KH, Ng CC, Hilmi I, Goh KL
    Genet. Mol. Res., 2012;11(3):3115-21.
    PMID: 23007989
    Crohn's disease is a chronic, relapsing inflammatory bowel disease; it affects the mucosa and deeper layers of the digestive wall. Two Crohn's disease patients who carried the JW1 variant and two patients who carried the SNP5 variant were investigated for other co-inherited polymorphisms that could influence Crohn's disease development. Based on the sequencing results, a homozygous 5'-UTR-59 G to A variant in exon 1 (SNP6) was observed in a patient who carried SNP5, while a heterozygous SNP6 variant was detected in the other patient who carried SNP5. No other associated mutations or polymorphisms were detected in the two patients who carried the JW1 variant of the CARD15/NOD2 gene.
    Matched MeSH terms: Exons/genetics
  14. Deletion analysis of SMN1 exon 7 alone may be necessary and sufficient for the diagnosis of spinal muscular atrophy
    Sasongko TH, Gunadi, Zilfalil BA, Zabidi-Hussin Z
    J. Neurogenet., 2011 Mar;25(1-2):15-6.
    PMID: 21338334 DOI: 10.3109/01677063.2011.559561
    The authors suggest a simplification for the current molecular genetic testing of spinal muscular atrophy (SMA). Deletion analysis of SMN1 exon 7 alone may be necessary and sufficient for the diagnosis of SMA. It is based on sole contribution of survival motor neuron 1 (SMN1) exon 7 to SMA pathogenesis.
    Matched MeSH terms: Exons/genetics*
  15. A nonsense mutation in exon 8 of the APC gene (Arg283Ter) causes clinically variable FAP in a Malaysian Chinese family
    Mohamed Z, Ahmad R, Yoke NS, Zakaria Z, Ahmad H, Yew TH
    Cancer Sci, 2003 Aug;94(8):725-8.
    PMID: 12901799 DOI: 10.1111/j.1349-7006.2003.tb01509.x
    The present study was carried out to characterize the causative genetic mutation in a medium-sized Malaysian Chinese pedigree of three generations affected with familial adenomatous polyposis (FAP). Clinical data and genetic studies revealed considerable phenotypic variability in affected individuals in this family. Blood was obtained from members of the FAP-01 family and genomic DNA was extracted. Mutation screening of the adenomatous polyposis coli (APC) gene was carried out using the single strand conformation polymorphism (SSCP) technique. The possibility of exon skipping was predicted by splicing motif recognition software (ESEfinder release2.0). SSCP results showed mobility shifts in exon 8 of the APC gene which segregated with affected members of the family. Sequence analysis revealed that the affected individuals are heterozygous for a C847T transition, whilst all the unaffected family members and control individuals are homozygous C at the same position. This nucleotide substitution generates a stop codon at amino acid position 283, in place of the usual arginine (Arg283Ter). We conclude that an Arg283Ter mutation in the APC gene is causative of the FAP phenotype in this family, although there is considerable variation in the presentation of this disease among affected individuals. Computational analysis predicts that this mutation occurs within sequences that may function as splicing signals, so that the sequence change may affect normal splicing.
    Matched MeSH terms: Exons/genetics*
  16. Genotyping of Malaysian G6PD-deficient neonates by reverse dot blot flow-through hybridisation
    Alina MF, Azma RZ, Norunaluwar J, Azlin I, Darnina AJ, Cheah FC, et al.
    J Hum Genet, 2020 Mar;65(3):263-270.
    PMID: 31863082 DOI: 10.1038/s10038-019-0700-7
    G6PD deficiency is the commonest enzyme deficiency found in humans. Current diagnostic methods lack sensitivity to detect all cases of G6PD deficiency. We evaluated the reverse dot blot flow-through hybridisation assay designed to detect simultaneously multiple known G6PD mutations in a group of Malaysian neonates. Archival DNA samples from 141 G6PD-deficient neonates were subjected to reverse dot blot flow-through hybridisation assay using the GenoArray Diagnostic Kit (Hybribio Limited, Hong Kong) and DNA sequencing. The method involved PCR amplification of 5 G6PD exons using biotinylated primers, hybridisation of amplicons to a membrane containing oligoprobes designed for G6PD mutations known to occur in the Malaysian population and colour detection by enzyme immunoassay. The assay detected 13 of the 14 G6PD mutations and genotyped 133 (94.3%) out of 141 (102 males, 39 females) cases. Among the 39 female G6PD-deficient neonates, there were 7 homozygous and 6 compound heterozygous cases. The commonest alleles were G6PD Viangchan 871G > A (21%) and G6PD Mahidol 487G > A(20%) followed by G6PD Mediterranean 563C > T, (14%), G6PD Vanua Lava 383T > C (12%), G6PD Canton 1376G > T (10%), G6PD Orissa 131C > G (6.3%) G6PD Coimbra 592C > T (5.6%) plus 6 other mutations. DNA sequencing of remaining cases revealed 6 cases of intron 11 nt 93C > T not previously reported in Malaysia and two novel mutations, one case each of nt 1361G > T and nt 1030G > A. We found the reverse dot blot assay easy to perform, rapid, accurate and reproducible, potentially becoming an improved diagnostic test for G6PD deficiency.
    Matched MeSH terms: Exons/genetics
  17. Polycythaemia Vera among Sudanese Patients with Special Emphasis on JAK2 Mutations
    Ibrahim IK, Hassan R, Ali EW, Omer A
    Asian Pac J Cancer Prev, 2019 Jan 25;20(1):41-44.
    PMID: 30677867
    Background: In recent years, a somatic point mutation in the Janus Kinase 2 (JAK2) gene (1849 G→T, V617F)
    has been reported to occur in over 90% of patients with polycythemia vera (PV). Another JAK2 mutation in exon 12
    had been described and shown capable of activating erythropoietin signaling pathways. Objective: In this study, we
    aimed to determine the frequency of Jak2 mutations (JAK2V617F and JAK2 exon 12) as well as their relationships
    with hematological parameters in Sudanese patients with myeloproliferative disorders (MPD). A comparison with
    findings of published studies from other geographic regions was included. Materials and Methods: From each of
    a total of 83 polycythaemia patients, six milliliters (ml) of venous blood were collected and processed for molecular
    analysis and measurement of serum erythropoietin level by enzyme-linked immunoassay (ELISA). The JAK2 V617F
    mutation was determined using an allele-specific competitive blocker (ACB) -PCR assay and High Resolution Melting
    (HRM) analysis was applied for the JAK2 exon 12 mutation. Results: According to patients’ history and the results
    for EPO levels, nine (10.7 %) out of 83 patients were found to have secondary polycythaemia and 74 (89.3%) PV. The
    overall frequency of the 2 JAK2 mutations was 94.6% in our Sudanese PV patients, JAK2V617F being found in 91%
    and JAK2 exon 12 mutations in 8.1%.Conclusion: In summary JAK2 V617F and JAK2 exon 12 mutations are very
    common in Sudanese PC cases.
    Matched MeSH terms: Exons/genetics*
  18. Fulltext Circular RNA enrichment in platelets is a signature of transcriptome degradation
    Alhasan AA, Izuogu OG, Al-Balool HH, Steyn JS, Evans A, Colzani M, et al.
    Blood, 2016 Mar 03;127(9):e1-e11.
    PMID: 26660425 DOI: 10.1182/blood-2015-06-649434
    In platelets, splicing and translation occur in the absence of a nucleus. However, the integrity and stability of mRNAs derived from megakaryocyte progenitor cells remain poorly quantified on a transcriptome-wide level. As circular RNAs (circRNAs) are resistant to degradation by exonucleases, their abundance relative to linear RNAs can be used as a surrogate marker for mRNA stability in the absence of transcription. Here we show that circRNAs are enriched in human platelets 17- to 188-fold relative to nucleated tissues and 14- to 26-fold relative to samples digested with RNAse R to selectively remove linear RNA. We compare RNAseq read depths inside and outside circRNAs to provide in silico evidence of transcript circularity, show that exons within circRNAs are enriched on average 12.7 times in platelets relative to nucleated tissues and identify 3162 genes significantly enriched for circRNAs, including some where all RNAseq reads appear to be derived from circular molecules. We also confirm that this is a feature of other anucleate cells through transcriptome sequencing of mature erythrocytes, demonstrate that circRNAs are not enriched in cultured megakaryocytes, and demonstrate that linear RNAs decay more rapidly than circRNAs in platelet preparations. Collectively, these results suggest that circulating platelets have lost >90% of their progenitor mRNAs and that translation in platelets occurs against the backdrop of a highly degraded transcriptome. Finally, we find that transcripts previously classified as products of reverse transcriptase template switching are both enriched in platelets and resistant to decay, countering the recent suggestion that up to 50% of rearranged RNAs are artifacts.
    Matched MeSH terms: Exons/genetics
  19. Identification of a novel HLA-A*01 variant, HLA-A*01:211, in a Singaporean Malay bone marrow donor
    Kaur A, Cho L, Cereb N, Lin PY, Yang KL
    HLA, 2020 09;96(3):329-330.
    PMID: 32227684 DOI: 10.1111/tan.13884
    One nucleotide substitution in codon 73 of HLA-A*01:01:01:01 results in a novel allele, HLA-A*01:211.
    Matched MeSH terms: Exons/genetics
  20. Structural analysis of a missense mutation (Val414Phe) in the catalytic core domain of the factor XIII(A) subunit
    Aslam S, Yee VC, Narayanan S, Duraisamy G, Standen GR
    Br J Haematol, 1997 Aug;98(2):346-52.
    PMID: 9266932
    Molecular analysis has been performed on a Malaysian patient with a severe bleeding disorder due to factor XIII(A) subunit deficiency. Total mRNA was isolated from the patient's leucocytes and four overlapping segments corresponding to the entire coding region of the A subunit cDNA were amplified by RT-PCR. The cDNA segments amplified efficiently and were of expected size. Direct sequencing of the complete reading frame revealed a single homozygous base change (nt 1327G-T) in exon 10 corresponding to a missense mutation, Val414Phe, in the catalytic core domain of the A subunit monomer. The mutation eliminates a BsaJ1 restriction site and family screening showed that both parents were heterozygous for the defect. The base substitution was absent in 55 normal individuals. Val414 is a highly conserved residue in the calcium-dependent transglutaminase enzyme family. Computer modelling based on 3D crystallographic data predicts that the bulky aromatic side chain of the substituted phenylalanine residue distorts protein folding and destabilizes the molecule. In addition, conformation changes in the adjacent catalytic and calcium binding regions of the A subunit are likely to impair the enzymatic activity of any protein synthesized.
    Matched MeSH terms: Exons/genetics
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