Displaying publications 1 - 20 of 78 in total

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  1. Fulltext A Malay boy with the Cornelia de Lange syndrome: clinical and molecular findings
    Bhuiyan ZA, Zilfalil BA, Hennekam RC
    Singapore Med J, 2006 Aug;47(8):724-7.
    PMID: 16865217
    The Cornelia de Lange syndrome is a multiple congenital anomaly syndrome characterised by dysmorphic facial features, hirsutism, severe growth and developmental delays, and malformed upper limbs. The prevalence is estimated to be one per 10,000. Recently, several independent groups proved that Cornelia de Lange syndrome is caused by mutations in the NIPBL gene, the human homologue of the Drosophila Nipped-B gene. Here, we present the first clinical case report of a Malay child, a 9-year-old boy with the Cornelia de Lange syndrome. We also report the molecular investigation of the NIPBL gene in this patient.
  2. Fulltext A genome wide pattern of population structure and admixture in peninsular Malaysia Malays
    Hatin WI, Nur-Shafawati AR, Etemad A, Jin W, Qin P, Xu S, et al.
    Hugo J, 2014 Dec;8(1):5.
    PMID: 27090253 DOI: 10.1186/s11568-014-0005-z
    BACKGROUND: The Malays consist of various sub-ethnic groups which are believed to have different ancestral origins based on their migrations centuries ago. The sub-ethnic groups can be divided based on the region they inhabit; the northern (Melayu Kedah and Melayu Kelantan), western (Melayu Minang) and southern parts (Melayu Bugis and Melayu Jawa) of Peninsular Malaysia. We analyzed 54,794 autosomal single nucleotide polymorphisms (SNPs) which were shared by 472 unrelated individuals from 17 populations to determine the genetic structure and distributions of the ancestral genetic components in five Malay sub-ethnic groups namely Melayu Bugis, Melayu Jawa, Melayu Minang, Melayu Kedah, and Melayu Kelantan. We also have included in the analysis 12 other study populations from Thailand, Indonesia, China, India, Africa and Orang Asli sub-groups in Malay Peninsula, obtained from the Pan Asian SNP Initiative (PASNPI) Consortium and International HapMap project database.

    RESULTS: We found evidence of genetic influx from Indians to Malays, more in Melayu Kedah and Melayu Kelantan which are genetically different from the other Malay sub-ethnic groups, but similar to Thai Pattani. More than 98% of these northern Malays haplotypes could be found in either Indians or Chinese populations, indicating a highly admixture pattern among populations. Nevertheless, the ancestry lines of Malays, Indonesians and Thais were traced back to have shared a common ancestor with the Proto-Malays and Chinese.

    CONCLUSIONS: These results support genetic admixtures in the Peninsular Malaysia Malay populations and provided valuable information on the enigmatic demographical history as well as shed some insights into the origins of the Malays in the Malay Peninsula.

  3. A new method for FMR1 gene methylation screening by multiplex methylation-specific real-time polymerase chain reaction
    Elias MH, Ankathil R, Salmi AR, Sudhikaran W, Limprasert P, Zilfalil BA
    Genet Test Mol Biomarkers, 2011 Jun;15(6):387-93.
    PMID: 21329465 DOI: 10.1089/gtmb.2010.0191
    Fragile X Syndrome (FXS) is the most common form of inherited mental retardation in men. It is caused by abnormalities in the FMR1 gene that are associated with CGG repeat expansion and the hypermethylation status of its promoter. Methylated alleles lead to transcriptional inhibition and consequent loss of Fragile X Mental Retardation Protein. Chemical modification of cytosine to uracil by bisulfite treatment has proved to be an attractive method for DNA methylation studies that precludes labor-intensive Southern blot analysis, which is the gold standard test for FXS. In this report, bisulfite-treated DNA samples were amplified using real-time multiplex methylation-specific polymerase chain reaction followed by melting curve analysis. Our results show that all control samples with known CGG repeat numbers and methylation statuses were correctly diagnosed. The samples from 43 male patients were also successfully diagnosed, which were in complete agreement with the results of Southern blotting. By such means, 39 patients were found to have an unmethylated allele; 3, a fully mutated allele; and 1, both methylated and unmethylated alleles, thus implying a diagnosis of mosaicism. In conclusion, we find our method to be convenient for screening a large number of male patients with FXS, because it is rapid and easy to perform, especially when there is a low quantity of DNA that must be sensitively and accurately assayed.
  4. Fulltext A new paradigm in medicine: genome wide association studies
    S, MARAN, LEE, Y. Y., ZILFALIL BA, NOORIZAN AM
    Buletin Persatuan Genetik Malaysia, 2011;18(1):3-6.
    MyJurnal
    Genome Wide Association (GWA) Studies of complex diseases represents a new paradigm in the
    post-genomic era. Since then, the eld of human genetics has been revolutionized by the GWA Studies approach (Yang and Hibberd 2009). Adding to this, the completion of human genome sequence had enabled a systemic identi cation of genetic loci that determines
    the etiology of complex diseases.
  5. A novel single nucleotide polymorphism, IVS2 -97A>T, in the prostaglandin F2alpha receptor gene was identified among the Malaysian patients with glaucoma
    Peng HB, Zahary MN, Tajudin LS, Lin CL, Teck CM, Sidek MR, et al.
    Kobe J Med Sci, 2007;53(1-2):49-52.
    PMID: 17582204
    The Prostaglandin F2alpha (PGF2alpha) receptor gene has been found to play an important role in reducing the intraocular pressure of the glaucomatous patients. Variations of the PGF2alpha receptor gene may be responsible for the differences in the response to an antiglaucoma drug, Latanoprost. A combined method of denaturing High Performance Liquid Chromatography (dHPLC) and sequencing was applied to detection of the PGF2alpha receptor gene variant among the 76 Malaysian patients with glaucoma, and a novel single nucleotide polymorphism (SNP), IVS -97A>T, was identified. According to the genotyping analysis, 36.8% of the subjects were heterozygous for the variant allele T, while 9.2% homozygous. The frequency of variant allele T was 0.28. Although with a limited number of samples, our data suggested that this polymorphism is common in the Malaysian patients with glaucoma.
  6. A simple and rapid genotyping method for beta-2 receptor (beta2 AR) gene using allele specific multiplex PCR
    Romaino SM, Teh LK, Zilfalil BA, Thong CP, Ismail AA, Amir J, et al.
    J Clin Pharm Ther, 2004 Feb;29(1):47-52.
    PMID: 14748897 DOI: 10.1046/j.1365-2710.2003.00535.x
    Polymorphism of the beta2-adrenergic receptor (beta2 AR) gene is an important determinant of the function of this receptor. It affects receptor down-regulation and beta2-agonist responses. It has also been a focus of interest in attempts to elucidate the genetic basis of asthma, hypertension, obesity and cystic fibrosis. Several different techniques have been established to determine beta2 AR genotypes but none of these methods are simple enough to detect simultaneously all the five alleles of our research interest (Arg16/Gly16, -20T/C, Gln27/Glu27, -47T/C and Thr164/Ile164).
  7. Fulltext A whole genome analyses of genetic variants in two Kelantan Malay individuals
    Wan Juhari WK, Md Tamrin NA, Mat Daud MH, Isa HW, Mohd Nasir N, Maran S, et al.
    Hugo J, 2014 Dec;8(1):4.
    PMID: 27090252 DOI: 10.1186/s11568-014-0004-0
    BACKGROUND: The sequencing of two members of the Royal Kelantan Malay family genomes will provide insights on the Kelantan Malay whole genome sequences. The two Kelantan Malay genomes were analyzed for the SNP markers associated with thalassemia and Helicobacter pylori infection. Helicobacter pylori infection was reported to be low prevalence in the north-east as compared to the west coast of the Peninsular Malaysia and beta-thalassemia was known to be one of the most common inherited and genetic disorder in Malaysia.

    RESULT: By combining SNP information from literatures, GWAS study and NCBI ClinVar, 18 unique SNPs were selected for further analysis. From these 18 SNPs, 10 SNPs came from previous study of Helicobacter pylori infection among Malay patients, 6 SNPs were from NCBI ClinVar and 2 SNPs from GWAS studies. The analysis reveals that both Royal Kelantan Malay genomes shared all the 10 SNPs identified by Maran (Single Nucleotide Polymorphims (SNPs) genotypic profiling of Malay patients with and without Helicobacter pylori infection in Kelantan, 2011) and one SNP from GWAS study. In addition, the analysis also reveals that both Royal Kelantan Malay genomes shared 3 SNP markers; HBG1 (rs1061234), HBB (rs1609812) and BCL11A (rs766432) where all three markers were associated with beta-thalassemia.

    CONCLUSIONS: Our findings suggest that the Royal Kelantan Malays carry the SNPs which are associated with protection to Helicobacter pylori infection. In addition they also carry SNPs which are associated with beta-thalassemia. These findings are in line with the findings by other researchers who conducted studies on thalassemia and Helicobacter pylori infection in the non-royal Malay population.

  8. Fulltext Adapting the ACMG/AMP variant classification framework: A perspective from the ClinGen Hemoglobinopathy Variant Curation Expert Panel
    Kountouris P, Stephanou C, Lederer CW, Traeger-Synodinos J, Bento C, Harteveld CL, et al.
    Hum Mutat, 2022 Aug;43(8):1089-1096.
    PMID: 34510646 DOI: 10.1002/humu.24280
    Accurate and consistent interpretation of sequence variants is integral to the delivery of safe and reliable diagnostic genetic services. To standardize the interpretation process, in 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published a joint guideline based on a set of shared standards for the classification of variants in Mendelian diseases. The generality of these standards and their subjective interpretation between laboratories has prompted efforts to reduce discordance of variant classifications, with a focus on the expert specification of the ACMG/AMP guidelines for individual genes or diseases. Herein, we describe our experience as a ClinGen Variant Curation Expert Panel to adapt the ACMG/AMP criteria for the classification of variants in three globin genes (HBB, HBA2, and HBA1) related to recessively inherited hemoglobinopathies, including five evidence categories, as use cases demonstrating the process of specification and the underlying rationale.
  9. Allele-specific PCR for a cost-effective & time-efficient diagnostic screening of spinal muscular atrophy
    Marini M, Sasongko TH, Watihayati MS, Atif AB, Hayati F, Gunadi, et al.
    Indian J Med Res, 2012;135:31-5.
    PMID: 22382180
    Genetic diagnosis of spinal muscular atrophy (SMA) is complicated by the presence of SMN2 gene as majority of SMA patients show absence or deletion of SMN1 gene. PCR may amplify both the genes non selectively in presence of high amount of DNA. We evaluated whether allele-specific PCR for diagnostic screening of SMA is reliable in the presence of high amount of genomic DNA, which is commonly used when performing diagnostic screening using restriction enzymes.
  10. An improved rapid genotyping method for the study of beta-2 adrenergic receptor gene polymorphisms using single tube allele specific multiplex PCR
    Zilfalil BA, Hoh BP, Nizam MZ, Liza-Sharmini AT, Teh LK, Ismail R
    J Clin Pharm Ther, 2006 Dec;31(6):637-40.
    PMID: 17176369
    Seventeen single nucleotide polymorphisms (SNPs) have been identified so far, within the beta-2 receptor (beta(2) AR) gene. The presence of so many SNPs within the beta(2) AR gene causes a problem, for those studying beta(2) AR pharmacogenetics, in relation to which SNPs to choose. Most of the work has focused on the three common SNPs within the coding block (alleles 16, 27 and 164) and the techniques developed have been for these three functionally important alleles.
  11. Analysis of Hereditary Nonpolyposis Colorectal Cancer in Malay Cohorts using Immunohistochemical Screening
    Wan Juhari WK, Wan Abdul Rahman WF, Mohd Sidek AS, Abu Hassan MR, Ahmad Amin Noordin KB, Zakaria AD, et al.
    Asian Pac J Cancer Prev, 2015;16(9):3767-71.
    PMID: 25987035
    BACKGROUND: Lynch syndrome (LS) is an inherited predisposition to colorectal, endometrial (uterine) and other cancers. Although most cancers are not inherited, about 5 percent (%) of people who have colorectal or endometrial cancer have the Lynch syndrome. It involves the alteration of mismatch repair (MMR) genes; MLH1, MSH2, MSH6 or PMS2. In this study, we analyzed the expression of MMR proteins in colorectal cancer in a Malay cohort by immunohistochemistry.

    MATERIALS AND METHODS: A total of 17 patients were selected fulfilling one of the Bethesda criteria: colorectal cancer diagnosed in a patient aged less than 50 years old, having synchronous and metachronous colorectal cancer or with a strong family history. Immunohistochemical staining was performed on paraffin embedded tumour tissue samples using four antibodies: MLH1, MSH2, MSH6 and PMS2.

    RESULTS: Twelve out of 17 patients (70.6%) were noted to have a family history. A total of 41% (n=7) of the patients had abnormal immunohistochemical staining with one or more of the four antibodies. Loss of expression were noted in 13 tumour tissues with a negative staining score <4. Of 13 tumour tissues, four showed loss expression of MLH1. For PMS2, loss of expression were noted in five cases. Both MSH2 and MSH6 showed loss of expression in two tumour tissues respectively.

    CONCLUSIONS: Revised Bethesda criteria and immunohistochemical analysis constituted a convenient approach and is recommended to be a first-line screening for Lynch syndrome in Malay cohorts.

  12. Fulltext Analysis of sequence variations in low-density lipoprotein receptor gene among Malaysian patients with familial hypercholesterolemia
    Al-Khateeb A, Zahri MK, Mohamed MS, Sasongko TH, Ibrahim S, Yusof Z, et al.
    BMC Med Genet, 2011;12:40.
    PMID: 21418584 DOI: 10.1186/1471-2350-12-40
    Familial hypercholesterolemia is a genetic disorder mainly caused by defects in the low-density lipoprotein receptor gene. Few and limited analyses of familial hypercholesterolemia have been performed in Malaysia, and the underlying mutations therefore remain largely unknown.We studied a group of 154 unrelated FH patients from a northern area of Malaysia (Kelantan). The promoter region and exons 2-15 of the LDLR gene were screened by denaturing high-performance liquid chromatography to detect short deletions and nucleotide substitutions, and by multiplex ligation-dependent probe amplification to detect large rearrangements.
  13. Analysis of the genetic structure of the Malay population: Ancestry-informative marker SNPs in the Malay of Peninsular Malaysia
    Yahya P, Sulong S, Harun A, Wan Isa H, Ab Rajab NS, Wangkumhang P, et al.
    Forensic Sci Int Genet, 2017 09;30:152-159.
    PMID: 28743033 DOI: 10.1016/j.fsigen.2017.07.005
    Malay, the main ethnic group in Peninsular Malaysia, is represented by various sub-ethnic groups such as Melayu Banjar, Melayu Bugis, Melayu Champa, Melayu Java, Melayu Kedah Melayu Kelantan, Melayu Minang and Melayu Patani. Using data retrieved from the MyHVP (Malaysian Human Variome Project) database, a total of 135 individuals from these sub-ethnic groups were profiled using the Affymetrix GeneChip Mapping Xba 50-K single nucleotide polymorphism (SNP) array to identify SNPs that were ancestry-informative markers (AIMs) for Malays of Peninsular Malaysia. Prior to selecting the AIMs, the genetic structure of Malays was explored with reference to 11 other populations obtained from the Pan-Asian SNP Consortium database using principal component analysis (PCA) and ADMIXTURE. Iterative pruning principal component analysis (ipPCA) was further used to identify sub-groups of Malays. Subsequently, we constructed an AIMs panel for Malays using the informativeness for assignment (In) of genetic markers, and the K-nearest neighbor classifier (KNN) was used to teach the classification models. A model of 250 SNPs ranked by In, correctly classified Malay individuals with an accuracy of up to 90%. The identified panel of SNPs could be utilized as a panel of AIMs to ascertain the specific ancestry of Malays, which may be useful in disease association studies, biomedical research or forensic investigation purposes.
  14. Fulltext Analysis of the survival motor neuron and neuronal apoptosis inhibitory protein genes in Malay patients with Spinal Muscular Atrophy
    Zilfalil BA, Zabidi-Hussin AMH, Watihayati MS, Rozainah MY, Naing L, Sutomo R, et al.
    Med J Malaysia, 2004 Oct;59(4):512-4.
    PMID: 15779584 MyJurnal
    In Malaysia, Spinal Muscular Atrophy (SMA) is diagnosed based on clinical observation with or without muscle biopsy. Molecular analyses of the SMA-related genes have not been available so far. In this preliminary study, we searched for homozygous deletion of Survival Motor Neuron (SMN1) and Neuronal Apoptosis Inhibitory Protein (NAIP) genes in Malay patients with SMA and found homozygous deletion of SMN1 exon 7 and 8 in all the patients while homozygous deletion of NAIP exon 5 was detected in only our type 1 patients but not in the type 3 patient. To the best of our knowledge, these are the first SMA cases diagnosed at the molecular level in Malaysia.
  15. Ancestry-informative marker (AIM) SNP panel for the Malay population
    Yahya P, Sulong S, Harun A, Wangkumhang P, Wilantho A, Ngamphiw C, et al.
    Int J Legal Med, 2020 Jan;134(1):123-134.
    PMID: 31760471 DOI: 10.1007/s00414-019-02184-0
    Ancestry-informative markers (AIMs) can be used to infer the ancestry of an individual to minimize the inaccuracy of self-reported ethnicity in biomedical research. In this study, we describe three methods for selecting AIM SNPs for the Malay population (Malay AIM panel) using different approaches based on pairwise FST, informativeness for assignment (In), and PCA-correlated SNPs (PCAIMs). These Malay AIM panels were extracted from genotype data stored in SNP arrays hosted by the Malaysian node of the Human Variome Project (MyHVP) and the Singapore Genome Variation Project (SGVP). In particular, genotype data from a total of 165 Malay individuals were analyzed, comprising data on 117 individual genotypes from the Affymetrix SNP-6 SNP array platform and data on 48 individual genotypes from the OMNI 2.5 Illumina SNP array platform. The HapMap phase 3 database (1397 individuals from 11 populations) was used as a reference for comparison with the Malay genotype data. The accuracy of each resulting Malay AIM panel was evaluated using a machine learning "ancestry-predictive model" constructed by using WEKA, a comprehensive machine learning platform written in Java. A total of 1250 SNPs were finally selected, which successfully identified Malay individuals from other world populations with an accuracy of 90%, but the accuracy decreased to 80% using 157 SNPs according to the pairwise FST method, while a panel of 200 SNPs selected using In and PCAIMs could be used to identify Malay individuals with an accuracy of approximately 80%.
  16. Fulltext Central resources of variant discovery and annotation and its role in precision medicine
    Halim-Fikri H, Syed-Hassan SR, Wan-Juhari WK, Assyuhada MGSN, Hernaningsih Y, Yusoff NM, et al.
    Asian Biomed (Res Rev News), 2022 Dec;16(6):285-298.
    PMID: 37551357 DOI: 10.2478/abm-2022-0032
    Rapid technological advancement in high-throughput genomics, microarray, and deep sequencing technologies has accelerated the possibility of more complex precision medicine research using large amounts of heterogeneous health-related data from patients, including genomic variants. Genomic variants can be identified and annotated based on the reference human genome either within the sequence as a whole or in a putative functional genomic element. The American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) mutually created standards and guidelines for the appraisal of proof to expand consistency and straightforwardness in clinical variation interpretations. Various efforts toward precision medicine have been facilitated by many national and international public databases that classify and annotate genomic variation. In the present study, several resources are highlighted with recognition and data spreading of clinically important genetic variations.
  17. Fulltext Chromosomal abnormalities and reproductive outcome in Malaysian couples with miscarriages
    Pal S, Ma SO, Norhasimah M, Suhaida MA, Siti Mariam I, Ankathil R, et al.
    Singapore Med J, 2009 Oct;50(10):1008-12.
    PMID: 19907893
    This study was done to determine the prevalence of chromosomal abnormalities and the subsequent reproductive outcome in couples who had two or more miscarriages.
  18. Chromosomal alterations in Malaysian patients with nasopharyngeal carcinoma analyzed by comparative genomic hybridization
    Natasya Naili MN, Hasnita CH, Shamim AK, Hasnan J, Fauziah MI, Narazah MY, et al.
    Cancer Genet. Cytogenet., 2010 Dec;203(2):309-12.
    PMID: 21156250 DOI: 10.1016/j.cancergencyto.2010.07.136
    Nasopharyngeal carcinoma (NPC) is one of the most common cancers in Malaysia, mainly occurring among the Chinese population. To detect common genetic alterations in NPC, we screened seven cases of NPC using the comparative genomic hybridization (CGH) technique. Before proceeding to the CGH technique, the tumors were first confirmed to consist of 75% tumor cells or more. In brief, the technique consists of binding tumor DNA with normal DNA and human Cot-1 DNA, which is then hybridized to normal metaphase spreads. The slides were then counterstained with 4,6 diamino-2-phenylindole (DAPI II) for detection. Analyses were performed using CGH software (Cytovision). We found genetic alterations in all seven NPC samples. The common chromosomal gains (57%, four cases) were found on chromosome arms 1q, 4p, 5, 7q, 11, 14p, 15q, 18p, and 21p, and common chromosomal losses (43%, three cases) were found on chromosome arm 16p. Our results showed chromosomal alterations in all seven NPC cases in the Malaysian population. This result provides the platform for further investigations to locate tumor suppressor genes and oncogenes at specific chromosomal regions in Malaysian NPC patients.
  19. Clinical and genetic analysis of long QT syndrome in two Malay children
    Wong AR, Zilfalil BA, Bhuiyan ZA
    Med J Malaysia, 2019 08;74(4):341-343.
    PMID: 31424047
    Long QT syndrome (LQTS) is predominantly a genetic cardiac arrhythmia disorder. We report here our study on long QT syndrome from two children from Kelantan, Malaysia. Clinical and genetic findings of these two unrelated Malay children with LQTS is discussed. We found a Long QT, type 1 causal mutation, p.Ile567Thr in the KCNQ1 gene in the first child. A pathogenic mutation could not be detected in the second child, explaining the heterogeneity of this disease.
  20. Clinical manifestations in trisomy 9
    Kannan TP, Hemlatha S, Ankathil R, Zilfalil BA
    Indian J Pediatr, 2009 Jul;76(7):745-6.
    PMID: 19475342 DOI: 10.1007/s12098-009-0158-2
    Complete trisomy 9 is a lethal diagnosis and most fetuses diagnosed thus die prenatally or during the early postnatal period and majority of such cases have been known to end in spontaneous abortion in the first trimester itself. One such rare survival of fetus ending in normal delivery and surviving until 20 days is reported here detailing the clinical manifestations of the child during the period of survival. The salient clinical features observed were small face, wide fontanel, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also webbed neck, characteristic of this trisomy 9 syndrome.
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