Displaying publications 61 - 80 of 135 in total

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  1. Wu YL, Lee V, Liam CK, Lu S, Park K, Srimuninnimit V, et al.
    Lung Cancer, 2018 12;126:1-8.
    PMID: 30527172 DOI: 10.1016/j.lungcan.2018.10.004
    OBJECTIVE: Patients with advanced non-small-cell lung cancer (NSCLC) with an adenocarcinoma component are recommended to undergo epidermal growth factor receptor (EGFR) mutation testing when being considered for EGFR targeted therapy. We conducted an exploratory analysis to inform the clinical utility of EGFR mutation testing in blood cell-free DNA using the cobas®EGFR Mutation Test v2.

    MATERIALS AND METHODS: Two EGFR mutation tests, a tissue-based assay (cobas® v1) and a tissue- and blood-based assay (cobas® v2) were used to analyze matched biopsy and blood samples (897 paired samples) from three Asian studies of first-line erlotinib with similar intent-to-treat populations. ENSURE was a phase III comparison of erlotinib and gemcitabine/platinum, FASTACT-2 was a phase III study of gemcitabine/platinum plus erlotinib or placebo, and ASPIRATION was a single-arm phase II study of erlotinib. Agreement statistics were evaluated, based on sensitivity and specificity between the two assays in subgroups of patients with increasing tumor burden.

    RESULTS: Patients with discordant EGFR (tissue+/plasma-) mutation status achieved longer progression-free and overall survival than those with concordant (tissue+/plasma+) mutation status. Tumor burden was significantly greater in patients with concordant versus discordant mutations. Pooled analyses of data from the three studies showed a sensitivity of 72.1% (95% confidence interval [CI] 67.8-76.1) and a specificity of 97.9% (95% CI 96.0-99.0) for blood-based testing; sensitivity was greatest in patients with larger baseline tumors.

    CONCLUSIONS: Blood-based EGFR mutation testing demonstrated high specificity and good sensitivity, and offers a convenient and easily accessible diagnostic method to complement tissue-based tests. Patients with a discordant mutation status in plasma and tissue, had improved survival outcomes compared with those with a concordant mutation status, which may be due to their lower tumor burden. These data help to inform the clinical utility of this blood-based assay for the detection of EGFR mutations.

    Matched MeSH terms: DNA Mutational Analysis/methods
  2. Choong ML, Koay ES, Khoo KL, Khaw MC, Sethi SK
    Clin Chem, 1997 Jun;43(6 Pt 1):916-23.
    PMID: 9191540
    The Arg-to-Trp substitution at codon 3500 in the apolipoprotein (apo) B-100 gene is established as a cause of familial defective apo B-100 (FDB), a functional mutation, resulting in reduced LDL receptor binding and manifest hypercholesterolemia. In a search for similar mutations in 163 Malaysians, we screened the putative receptor-binding region (codons 3456-3553) of the apo B-100 gene by PCR amplification and denaturing gradient-gel electrophoresis. Four single-base mutations were detected and confirmed by DNA sequencing. Two females, a Chinese and a Malay, had the same CGG3500-->TGG mutation, resulting in an Arg3500-to-Trp substitution. This is the second published report of such an independent mutation involving the same codon as the established Arg3500-to-Gln mutation. The two other mutations detected, CTT3517-->CTG and GCC3527-->GCT, resulted in degenerate codons with no amino acid substitutions. All four mutations were associated with a unique apo B haplotype, different from those found in Caucasian FDB patients but concurring with that previously reported for two other Asians with FDB.
    Matched MeSH terms: DNA Mutational Analysis/methods
  3. Numata S, Teye K, Krol RP, Karashima T, Fukuda S, Matsuda M, et al.
    J. Dermatol. Sci., 2015 Apr;78(1):82-5.
    PMID: 25766764 DOI: 10.1016/j.jdermsci.2015.02.006
    Matched MeSH terms: DNA Mutational Analysis
  4. Ghodsinejad Kalahroudi V, Kamalidehghan B, Arasteh Kani A, Aryani O, Tondar M, Ahmadipour F, et al.
    PLoS One, 2014;9(9):e106656.
    PMID: 25216246 DOI: 10.1371/journal.pone.0106656
    Oculocutaneous albinism (OCA) is a heterogeneous group of autosomal recessive disorders resulting from mutations of the tyrosinase (TYR) gene and presents with either complete or partial absence of pigment in the skin, hair and eyes due to a defect in an enzyme involved in the production of melanin. In this study, mutations in the TYR gene of 30 unrelated Iranian OCA1 patients and 100 healthy individuals were examined using PCR-sequencing. Additionally, in order to predict the possible effects of new mutations on the structure and function of tyrosinase, these mutations were analyzed by SIFT, PolyPhen and I-Mutant 2 software. Here, two new pathogenic p.C89S and p.H180R mutations were detected in two OCA1 patients. Moreover, the R402Q and S192Y variants, which are common non-pathogenic polymorphisms, were detected in 17.5% and 35% of the patients, respectively. The outcome of this study has extended the genotypic spectrum of OCA1 patients, which paves the way for more efficient carrier detection and genetic counseling.
    Matched MeSH terms: DNA Mutational Analysis
  5. Phuah SY, Lee SY, Kang P, Kang IN, Yoon SY, Thong MK, et al.
    PLoS One, 2013;8(8):e73638.
    PMID: 23977390 DOI: 10.1371/journal.pone.0073638
    The partner and localizer of breast cancer 2 (PALB2) is responsible for facilitating BRCA2-mediated DNA repair by serving as a bridging molecule, acting as the physical and functional link between the breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2) proteins. Truncating mutations in the PALB2 gene are rare but are thought to be associated with increased risks of developing breast cancer in various populations.
    Matched MeSH terms: DNA Mutational Analysis
  6. Hussin A, Md Nor NS, Ibrahim N
    Antiviral Res, 2013 Nov;100(2):306-13.
    PMID: 24055837 DOI: 10.1016/j.antiviral.2013.09.008
    Eleven strains of acyclovir (ACV)-resistant herpes simplex virus type 1 (HSV-1) were generated from HSV-1 clinical isolates by exposure to ACV. Genotype of the thymidine kinase (TK) and DNA polymerase (pol) genes from these mutants were further analyzed. Genotypic analysis revealed four non-synonymous mutations in TK gene associated with gene polymorphism and two to three non-synonymous mutations in DNA pol gene. Seven and six strains contained at least one resistance-associated mutation at TK and DNA pol gene, respectively. Resistance-associated mutations within the TK gene consisted of 64% of non-synonymous frameshift mutations within the homopolymer region of G's and C's, and 36% of non-synonymous nucleotide substitutions of the conserved gene region (C336Y, R51W and R222H), nucleotide that produced stop codon (L288Stop) and two amino acid substitutions outside the conserved region (E39G & L208F). There were 10 non-synonymous amino acid substitutions located outside the conserved region with the unclear significance to confer resistance observed. Resistance-associated mutations in DNA pol gene include insertion of G at the homopolymer region of G's (794-797) and amino acid substitutions inside (V621S) or outside (H1228D) the conserved region. In silico analysis of the mutated TK (C336Y, R51W and L208F), and DNA pol (V621S and H1228D) suggested structural changes that might alter the stability of these proteins. However, there were several mutations with unclear significance to confer ACV-resistance identified, especially mutations outside the conserved region.
    Matched MeSH terms: DNA Mutational Analysis
  7. Balraj P, Ahmad M, Khoo AS, Ayob Y
    Malays J Pathol, 2012 Jun;34(1):67-9.
    PMID: 22870602 MyJurnal
    Haemophilia B is caused by coagulation defects in the factor IX gene located in Xq27.1 on the X chromosome. Identification of mutations contributing to defective factor IX may be advantageous for precise carrier and prenatal diagnosis. We studied 16 patients from 11 families, consisting of 8 patients of the Malay ethnic group, of which 6 were siblings. Factor IX mutations have not been previously reported in the Malay ethnic group. The functional region of the factor IX gene was sequenced and mutations were identified in either the exon or intronic regions in 15 of the patients. One novel mutation, 6660_6664delTTCTT was identified in siblings with moderate form of haemophilia B. Mutations identified in our patients when linked with disease severity were similar to findings in other populations. In summary, this preliminary data will be used to build a Malaysian mutation database which would facilitate genetic counseling.
    Matched MeSH terms: DNA Mutational Analysis
  8. Balraj P, Lim PG, Sidek H, Wu LL, Khoo AS
    J. Endocrinol. Invest., 2013 Jun;36(6):366-74.
    PMID: 23027774 DOI: 10.3275/8648
    Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is a common autosomal recessive disorder. Our objective was to identify the 21-hydroxylase active gene, CYP21A2 mutations in Malaysian 21-OHD patients using different techniques.
    Matched MeSH terms: DNA Mutational Analysis
  9. Chua KH, Puah SM, Chew CH, Wong CH, Goh KL
    Pancreatology, 2011;11(4):441-4.
    PMID: 21952138 DOI: 10.1159/000330943
    Hereditary pancreatitis (HP) is a very rare form of early-onset chronic pancreatitis, which usually begins in childhood with a variable spectrum of severity of disease. HP is commonly caused by variants/mutations in the PRSS1 gene as reported in many studies. Therefore, in this study, we aimed to investigate the possible association of PRSS1 gene variants/mutations in a Malaysian Chinese family with HP.
    Matched MeSH terms: DNA Mutational Analysis
  10. Yusnita Y, Norsiah MD, Rahman AJ
    Malays J Pathol, 2010 Dec;32(2):103-10.
    PMID: 21329181 MyJurnal
    Mitochondrial Subunit ND1 (mtND1) gene is involved in the first step of the electron transport chain of oxidative phosphorylation (OXPHOS). Alteration of the electron transport components by mutations in mtDNA may compromise the normal electron flow. This could lead to an increase of bifurcation and generation of superoxidase radicals and increase oxidative stress in various types of cancer cells. Genomic DNA was extracted from thirty matched primary colorectal tumour tissues and matching non-tumour tissues. Blood samples were obtained from twenty-five normal people. The mtNDI coding region was amplified by step-down PCR. The purified products were then subjected to direct sequencing and subsequently, the DNA sequences obtained were compared with the revised Cambridge Reference Sequence (rCRS) and MITOMAP. From the analysis, the mtND1 gene showed 11 (45.8%) different mutations and also 13 (54.2%) polymorphisms. The heteroplasmic mutation A4123A/G (I273I/V) might have a pathogenic significance as it fulfills various pathogenic criteria. Three mutations, T3394C (Y30H), A3434G (Y43C) and C3497T (A64V) which occur in a highly conserved region were likely to alter the structure and function of the ND1 protein. We suggest that these mutations, and in combination with the polymorphic variance in mtDNA, may cause slight changes that generate subtly higher levels of toxic reactive oxygen species (ROS).
    Matched MeSH terms: DNA Mutational Analysis
  11. Wong FL, Boo NY, Ainoon O, Wang MK
    Malays J Pathol, 2009 Dec;31(2):99-104.
    PMID: 20514852 MyJurnal
    This study aimed to determine the prevalence of four variants of organic anion transporter polypeptide 2 (OATP2) gene, and their association with severe hyperbilirubinemia.
    Matched MeSH terms: DNA Mutational Analysis
  12. Teh LK, Zahri MK, Zakaria ZA, Ismail R, Salleh MZ
    J Clin Pharm Ther, 2010 Dec;35(6):723-8.
    PMID: 21054465 DOI: 10.1111/j.1365-2710.2009.01146.x
    CYP2C8 is involved in the cytochrome P450 (CYP) epoxygenase pathway. Arachidonic acid metabolites such as epoxyeicosatrienenoic acids and hydroxyeicosatetrenoic acids, produced may have a role in hypertension. We aimed to develop a medium through-put method for screening samples of known and new mutations of CYP2C8 using denaturing high performance liquid chromatography (DHPLC).
    Matched MeSH terms: DNA Mutational Analysis
  13. Ariffin H, Martel-Planche G, Daud SS, Ibrahim K, Hainaut P
    Cancer Genet. Cytogenet., 2008 Oct;186(1):49-53.
    PMID: 18786442 DOI: 10.1016/j.cancergencyto.2008.06.004
    We report on a Malaysian kindred with Li-Fraumeni syndrome. The proband was an 8-year-old girl who presented with embryonal rhabdomyosarcoma of the trunk at the age of 8 months and developed a brain recurrence at the age of 7 years, which was 5 years after remission. A younger sister later developed adrenocortical carcinoma at the age of 6 months. Their mother and maternal grandmother were diagnosed with breast cancer at the ages of 26 and 38 years, respectively. TP53 mutation detection in this family revealed a duplication of a GGCGTG motif starting at nucleotide 17579 in exon 10, resulting in an in-frame insertion of two amino acids between residues 334 and 336 in the tetramerization domain of the p53 protein. This mutation was found in the proband and her affected sister as well as her mother. In addition, the mutation was detected in two other siblings (a brother aged 3 years and a sister aged 18 months) who have not yet developed any malignancy. Sequencing of TP53 in the father and two other asymptomatic siblings revealed wild-type TP53. To our knowledge, this is a first report of a Li-Fraumeni syndrome family in Southeast Asia.
    Matched MeSH terms: DNA Mutational Analysis
  14. Teong YT, Teo ST, Tan LP, Wu BQ, Peh SC
    Med J Malaysia, 2006 Dec;61(5):526-33.
    PMID: 17623951 MyJurnal
    Gastrointestinal stromal tumour (GIST) is a rare but most common mesenchymal tumour in the gastrointestinal tract. Although GIST research has been carried out extensively worldwide, it has yet to be studied in Malaysia. To establish the immunohistochemical expression pattern of CD117 (c-KIT), CD34, S-100 and Desmin, the incidence of c-KIT and PDGFRA genes mutation in GISTs, and correlate it with clinicopathological parameters. Eleven clinically diagnosed GISTs were stained for CD117, CD34, Desmin and S-100 protein by immunohistochemical technique, and c-KITand PDGFRA gene mutations were studied by PCR-CSGE-DNA sequencing method. All GISTs (7 cases) stain positive for CD117, and co-expressed CD34. None of these cases express Desmin, and only one expressed S-100 protein focally. Fifty-seven percent (4/7 cases) of GIST harboured mutations at exon 11 of c-KIT gene, and they were all high risk and malignant cases. No mutation was detected at exons 9, 13 and 17 of KIT gene, and exons 12 and 18 of PDGFRA gene. Immunohistochemistry using a panel of antibodies shows consistent pattern of CD117 and CD34 expression in GIST, and mutational study may be a useful prognostic marker for kinase inhibitor treatment of GIST.
    Matched MeSH terms: DNA Mutational Analysis
  15. Azian M, Hapizah MN, Khalid BA, Khalid Y, Rosli A, Jamal R
    Malays J Pathol, 2006 Jun;28(1):7-15.
    PMID: 17694954 MyJurnal
    Familial hypercholesterolaemia (FH) and Familial defective apolipoprotein B100 (FDB) are autosomal dominant inherited diseases of lipid metabolism caused by mutations in the low density lipoprotein (LDL) receptor and apolipoprotein B 100 genes. FH is clinically characterised by elevated concentrations of total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), presence of xanthomata and premature atherosclerosis. Both conditions are associated with coronary artery disease but may be clinically indistinguishable. Seventy-two (72) FH patients were diagnosed based on the Simon Broome's criteria. Mutational screening was performed by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). Positive mutations were subjected to DNA sequencing for confirmation of the mutation. We successfully amplified all exons in the LDL receptor and apo B100 genes. DGGE was performed in all exons of the LDL receptor (except for exons 4-3', 18 and promoter region) and apo B100 genes. We have identified four different mutations in the LDL receptor gene but no mutation was detected in the apo B 100 gene. The apo B100 gene mutation was not detected on DGGE screening as sequencing was not performed for negative cases on DGGE technique. To our knowledge, the C234S mutation (exon 5) is a novel mutation worldwide. The D69N mutation (exon 3) has been reported locally while the R385W (exon 9) and R716G (exon 15) mutations have not been reported locally. However, only 4 mutations have been identified among 14/72 patients (19.4%) in 39 FH families. Specificity (1-false positive) of this technique was 44.7% based on the fact that 42/76 (55.3%) samples with band shifts showed normal DNA sequencing results. A more sensitive method needs to be addressed in future studies in order to fully characterise the LDLR and apo B100 genes such as denaturing high performance liquid chromatography. In conclusion, we have developed the DNA analysis for FH patients using PCR-DGGE technique. DNA analysis plays an important role to characterise the type of mutations and forms an adjunct to clinical diagnosis.
    Matched MeSH terms: DNA Mutational Analysis
  16. Kham SK, Yin SK, Quah TC, Loong AM, Tan PL, Fraser A, et al.
    J Pediatr Hematol Oncol, 2004 Dec;26(12):817-9.
    PMID: 15591902
    DNA technology provides a new avenue to perform neonatal screening tests for single-gene diseases in populations of high frequency. Thalassemia is one of the high-frequency single-gene disorders affecting Singapore and many countries in the malaria belt. The authors explored the feasibility of using PCR-based diagnostic screening on 1,116 unselected sequential cord blood samples for neonatal screening. The cord blood samples were screened for the most common reported alpha- and beta-thalassemia mutations in each ethnic group (Chinese, Malays, and Indians) in a multiracial population. The carrier frequency for alpha-thalassemia mutations was about 6.4% in the Chinese (alpha deletions = 3.9%, alpha deletions = 2.5%), 4.8% in Malays, and 5.2% in Indians. Only alpha deletions were observed in the Chinese. The carrier frequency for beta-thalassemia mutations was 2.7% in the Chinese, 6.3% in Malays, and 0.7% in Indians. Extrapolating to the population distribution of Singapore, the authors found a higher overall expected carrier frequency for alpha- and beta-thalassemia mutations of 9% compared with a previous population study of 6% by phenotype. The highly accurate results make this molecular epidemiologic screening an ideal method to screen for and prevent severe thalassemia in high-risk populations.
    Matched MeSH terms: DNA Mutational Analysis
  17. Sutomo R, Talib NA, Yusoff NM, Van Rostenberghe H, Sadewa AH, Sunarti, et al.
    Pediatr Int, 2004 Oct;46(5):565-9.
    PMID: 15491385
    There are significant differences in the prevalence and severity of neonatal jaundice among various populations. Recently, it has been reported that a mutation of the UGT1A1 gene, glycine to arginine at codon 71 (G71R), is related to the development of neonatal jaundice in East Asian populations. However, whether the G71R mutation contributes to the high incidence of neonatal jaundice in different Asian populations remains unknown. The authors screened for this mutation in the Javanese-Indonesian and Malay-Malaysian populations.
    Matched MeSH terms: DNA Mutational Analysis
  18. Rani AQ, Sasongko TH, Sulong S, Bunyan D, Salmi AR, Zilfalil BA, et al.
    J. Neurogenet., 2013 Jun;27(1-2):11-5.
    PMID: 23438214 DOI: 10.3109/01677063.2012.762580
    We undertook the clinical feature examination and dystrophin analysis using multiplex ligation-dependent probe amplification (MLPA) and direct DNA sequencing of selected exons in a cohort of 35 Malaysian Duchenne/Becker muscular dystrophy (DMD/BMD) patients. We found 27 patients with deletions of one or more exons, 2 patients with one exon duplication, 2 patients with nucleotide deletion, and 4 patients with nonsense mutations (including 1 patient with two nonsense mutations in the same exon). Although most cases showed compliance to the reading frame rule, we found two unrelated DMD patients with an in-frame deletion of the gene. Two novel mutations have been detected in the Dystrophin gene and our results were compatible with other studies where the majority of the mutations (62.8%) are located in the distal hotspot. However, the frequency of the mutations in our patient varied as compared with those found in other populations.
    Matched MeSH terms: DNA Mutational Analysis
  19. Mohd Yusoff N, Shirakawa T, Nishiyama K, Choo KE, Isa MN, Matsuo M
    PMID: 15906717
    Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked red blood cell enzymopathy common in malaria endemic areas. Individuals affected by this disease show a wide variety of clinical signs of acute hemolytic anemia. Mutations of the G6PD gene in the Malay population with G6PD deficiency in Kelantan, a state in North East Malaysia were studied. Ninety-three individuals with G6PD deficiency were subjected to mutation analysis of the G6PD gene using polymerase chain reaction based techniques of multiplex PCR. Of the ninety-three DNA samples studied, molecular defects were identified in 80 cases (86%). Variants were heterogeneous - 28.7% were found to have a G to A nucleotide change at nucleotide 871 of the G6PD gene (G871A), corresponding to G6PD Viangchan. The other major mutations were G6PD Mediterranean, G6PD Vanua Lava, G6PD Coimbra, G6PD Kaiping, G6PD Orissa, G6PD Mahidol, G6PD Canton and G6PD Chatham. These results showed that there are heterogeneous mutations of the G6PD gene associated with G6PD deficiency and that G6PD Viangchan and G6PD Mediterranean account for the main variants in G6PD deficiency among the Malay population in Malaysia.
    Matched MeSH terms: DNA Mutational Analysis
  20. Yenchitsomanus PT, Sawasdee N, Paemanee A, Keskanokwong T, Vasuvattakul S, Bejrachandra S, et al.
    J Hum Genet, 2003;48(9):451-456.
    PMID: 12938018 DOI: 10.1007/s10038-003-0059-6
    We have previously demonstrated that compound heterozygous (SAO/G701D) and homozygous (G701D/G701D) mutations of the anion exchanger 1 (AE1) gene, encoding erythroid and kidney AE1 proteins, cause autosomal recessive distal renal tubular acidosis (AR dRTA) in Thai patients. It is thus of interest to examine the prevalence of these mutations in the Thai population. The SAO and G701D mutations were examined in 844 individuals from north, northeast, central, and south Thailand. Other reported mutations including R602H, DeltaV850, and A858D were also examined in some groups of subjects. The SAO mutation was common in the southern Thai population; its heterozygote frequency was 7/206 and estimated allele frequency 1.70%. However, this mutation was not observed in populations of three other regions of Thailand. In contrast, the G701D mutation was not found in the southern population but was observed in the northern, northeastern, and central populations, with heterozygote frequencies of 1/216, 3/205, and 1/217, and estimated allele frequencies of 0.23%, 0.73%, and 0.23%, respectively. The higher allele frequency of the G701D mutation in the northeastern Thai population corresponds to our previous finding that all Thai patients with AR dRTA attributable to homozygous G701D mutation originate from this population. This suggests that the G701D allele that is observed in this region might arise in northeastern Thailand. The presence of patients with compound heterozygous SAO/G701D in southern Thailand and Malaysia and their apparently absence in northeastern Thailand indicate that the G701D allele may have migrated to the southern peninsular region where SAO is common, resulting in pathogenic allelic interaction.
    Matched MeSH terms: DNA Mutational Analysis
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