Displaying publications 41 - 60 of 73 in total

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  1. Dorajoo R, Blakemore AI, Sim X, Ong RT, Ng DP, Seielstad M, et al.
    Int J Obes (Lond), 2012 Jan;36(1):159-63.
    PMID: 21544081 DOI: 10.1038/ijo.2011.86
    Recent genome-wide association studies (GWAS) have identified 38 obesity-associated loci among European populations. However, their contribution to obesity in other ethnicities is largely unknown.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  2. Haerian BS, Lim KS, Tan HJ, Wong CP, Wong SW, Tan CT, et al.
    Synapse, 2011 Oct;65(10):1073-9.
    PMID: 21465568 DOI: 10.1002/syn.20939
    The SYN2 rs3773364 A>G polymorphism has been proposed to be involved in susceptibility to epilepsy, but research results have been inconclusive. The aim of this study was to investigate the association between the SYN2 rs3773364 A>G polymorphism and susceptibility against epilepsy in a case-control study and a meta-analysis.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  3. Chen J, Teo YY, Toh DS, Sung C
    Pharmacogenomics, 2010 Aug;11(8):1077-94.
    PMID: 20712526 DOI: 10.2217/pgs.10.79
    The frequencies of alleles implicated in drug-response variability provide vital information for public health management. Differences in frequencies between genetically diverse groups of individuals can hamper drug assessments, particularly in populations where clinical data are not readily available.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  4. Teh LK, Lee WL, Amir J, Salleh MZ, Ismail R
    J Clin Pharm Ther, 2007 Jun;32(3):313-9.
    PMID: 17489883
    P-glycoprotein (PgP) is the most extensively studied ATP-binding cassette (ABC) coded by MDR1 gene. To date, 29 single nucleotide polymorphisms (SNPs) have been identified; but only SNP C3435T has been correlated with intestinal PgP expression levels and shown to influence the absorption of orally taken drugs that are PgP substrates. Individuals homozygous for the T allele have more than fourfold lower PgP expression compared with C/C individuals. We developed a one step primer based allele specific PCR method to detect SNP at C3435T to investigate the distribution of this genotype in the local population.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  5. Wang B, Ngoi S, Wang J, Chong SS, Lee CG
    Mol. Pharmacol., 2006 Jul;70(1):267-76.
    PMID: 16608921
    The MDR1 multidrug transporter represents one of the better characterized drug transporters that play an important role in protecting the body against xenobiotic insults. Single nucleotide polymorphisms (SNPs) and SNP haplotypes within this gene have been variously associated with differences in MDR1 expression/function, drug response as well as disease susceptibility. Nonetheless, the effect of polymorphisms at the MDR1 promoter region on its promoter activity remains less characterized. Through the examination of approximately 1.5 kilobases of MDR1 promoter region from five populations, including the Chinese, Malays, Indians, European Americans, and African Americans, we identified eight low-frequency SNPs, of which only two were polymorphic in at least four of the five populations examined. The other SNPs are mainly population-specific, the majority of which occur only in the African-American population. Recapitulation of the various combinations of SNP haplotypes in vitro in promoter-reporter assays revealed a few notable trends. The African and European American-specific haplotypes tended to result in enhanced MDR1 promoter activity only in the human embryonic kidney (HEK) 293 cell line. Haplotype GCTAACC, which occurs at variable frequencies in all the populations examined, with Asians having much lower frequencies (<2%) compared with the European Americans/African Americans (>4%), affected MDR1 promoter activity differently in different cell lines. Compared with the commonest haplotype, GCTA-ACC haplotype resulted in a significant decrease in MDR1 promoter activity in HeLa cells (P < 0.05) but a significant increase in the same promoter activity in HEK293 cells (P < 0.05). These results suggest that the MDR1 promoter region is largely invariant but that different haplotypes have differential effects on the MDR1 promoter activity in different cell lines.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  6. Jalil NJ, Bannur Z, Derahman A, Maskon O, Darinah N, Hamidi H, et al.
    J Pharm Pharm Sci, 2015;18(3):474-83.
    PMID: 26517138
    PURPOSE:   Enzymes potentially responsible for the pharmacokinetic variations of aspirin include cyclooxygenase-1 (COX-1), UDP-glucuronosyltransferase (UGT1A6) and P450 (CYP) (CYP2C9). We therefore aimed to determine the types and frequencies of variants of COX-1 (A-842G), UGT1A6 (UGT1A6*2; A541G and UGT1A6*3; A522C) and CYP2C9 (CYP2C9*3; A1075C) in the three major ethnic groups in Malaysia. In addition, the role of these polymorphisms on aspirin-induced gastritis among the patients was investigated.

    METHODS: A total of 165 patients with cardiovascular disease who were treated with 75-150 mg daily dose of aspirin and 300 healthy volunteers were recruited. DNA was extracted from the blood samples and genotyped for COX-1 (A-842G), UGT1A6 (UGT1A6*2 and UGT1A6*3) and CYP2C9 (CYP2C9*3; A1075C) using allele specific polymerase chain reaction (AS-PCR).

    RESULTS: Variants UGT1A6*2,*3 and CYP2C9*3 were detected in relatively high percentage of 22.83%, 30.0% and 6.50%, respectively; while COX-1 (A-842G) was absent. The genotype frequencies for UGT1A6*2 and *3 were significantly different between Indians and Malays or Chinese. The level of bilirubin among patients with different genotypes of UGT1A6 was significantly different (p-value < 0.05). In addition, CYP2C9*3 was found to be associated with gastritis with an odd ratio of 6.8 (95 % Cl OR: 1.39 - 33.19; P = 0.033).

    CONCLUSION: Screening of patients with defective genetic variants of UGT1A6 and CYP2C9*3 helps in identifying patients at risk of aspirin induced gastritis. However, a randomised clinical study of bigger sample size would be needed before it is translated to clinical use.

    Matched MeSH terms: European Continental Ancestry Group/genetics
  7. Lim LC, Tan HH, Lee LH, Tien SL, Abdul Ghafar A
    Ann Acad Med Singap, 1999 Mar;28(2):252-5.
    PMID: 10497677
    Resistance to activated protein C (APC-R) is the commonest inherited cause of thrombosis among Caucasians. Few studies have been carried out on its prevalence in Asians. We conducted a prospective study on 60 patients with thromboembolism to determine its prevalence in our local population. The Factor V Leiden (VaQ506) mutation associated with this condition was detected by amplification of the Factor V gene by polymerase chain reaction (PCR) and digestion of the fragment with Mnl I. Three patients were found to be heterozygous for this mutation. None of the 3 patients had other concomitant hypercoagulable states. In addition, we studied the prevalence of this condition in Malays which was found to be 0.5%. Our study suggests that the incidence of APC-R is much lower here compared to the West.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  8. Lim KB, Jeevan NH, Jaya P, Othman MI, Lee YH
    Forensic Sci Int, 2001 Jun 01;119(1):109-12.
    PMID: 11348801
    Allele frequencies for the nine STRs genetic loci included in the AmpFlSTR Profiler kit were obtained from samples of unrelated individuals comprising 139-156 Malays, 149-153 Chinese and 132-135 Indians, residing in Malaysia.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  9. Lim JM, Hong AG, Raman S, Shyamala N
    Ultrasound Obstet Gynecol, 2000 Feb;15(2):131-7.
    PMID: 10775996
    To determine whether racial differences affect the relationship between the fetal femur diaphysis length and the neonatal crown-heel length.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  10. Deurenberg-Yap M, Schmidt G, van Staveren WA, Deurenberg P
    Int. J. Obes. Relat. Metab. Disord., 2000 Aug;24(8):1011-7.
    PMID: 10951540
    OBJECTIVE: To study the relationship between body fat percentage and body mass index (BMI) in three different ethnic groups in Singapore (Chinese, Malays and Indians) in order to evaluate the validity of the BMI cut-off points for obesity.
    DESIGN: Cross-sectional study.
    SUBJECTS: Two-hundred and ninety-one subjects, purposively selected to ensure adequate representation of range of age and BMI of the general adult population, with almost equal numbers from each ethnic and gender group.
    MEASUREMENTS: Body weight, body height, sitting height, wrist and femoral widths, skinfold thicknesses, total body water by deuterium oxide dilution, densitometry with Bodpod(R) and bone mineral content with Hologic(R) QDR-4500. Body fat percentage was calculated using a four-compartment model.
    RESULTS: Compared with body fat percentage (BF%) obtained using the reference method, BF% for the Singaporean Chinese, Malays and Indians were under-predicted by BMI, sex and age when an equation developed in a Caucasian population was used. The mean prediction error ranged from 2.7% to 5.6% body fat. The BMI/BF% relationship was also different among the three Singaporean groups, with Indians having the highest BF% and Chinese the lowest for the same BMI. These differences could be ascribed to differences in body build. It was also found that for the same amount of body fat as Caucasians who have a body mass index (BMI) of 30 kg/m2 (cut-off for obesity as defined by WHO), the BMI cut-off points for obesity would have to be about 27 kg/m2 for Chinese and Malays and 26 kg/m2 for Indians.
    CONCLUSIONS: The results show that the relationship between BF% and BMI is different between Singaporeans and Caucasians and also among the three ethnic groups in Singapore. If obesity is regarded as an excess of body fat and not as an excess of weight (increased BMI), the cut-off points for obesity in Singapore based on the BMI would need to be lowered. This would have immense public health implications in terms of policy related to obesity prevention and management.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  11. Tan JA, Tay JS, Aziz NB, Saha N
    Hum. Hered., 1996 Jul-Aug;46(4):236-8.
    PMID: 8807327
    Restriction fragment length polymorphism (RFLP) of the gene encoding the beta chain of the human T cell receptor (TcR) was studied in three ethnic groups in Singapore by Southern blotting. Polymorphism in the beta chain gene was identified in BglII-digested DNA samples using a 770-bp TcR beta cDNA clone containing the joining and constant region segments. The TcR beta/BglII polymorphism was studied in 136 Chinese, 93 Indian and 88 Malay samples. The frequency of the less frequent allele (TcR beta*2) in all the ethnic groups was significantly lower (0.15-0.29, p < 0.01) than that in the Caucasians (0.46). Indians had a significantly lower frequency of this allele (0.15) than the Chinese (0.29) and Malays (0.26).
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  12. Lee EJ, Wong JY, Yeoh PN, Gong NH
    Pharmacogenetics, 1995 Oct;5(5):332-4.
    PMID: 8563775
    Glutathione S-transferase-theta (GSTT1) is subject to a genetic polymorphism where approximately 50% of a Caucasian population are homozygous for the null allele. Because of the possible association of the polymorphism with increased cancer risk in individuals, we genotyped by polymerase chain reaction 187 normal Chinese, 167 normal Malays and 152 normal Indians from Singapore and Malaysia. The proportion of Chinese, Malays and Indians with the null genotype were 58%, 38% and 16% respectively and mirrored previously reported frequencies of the GSTM1 null genotype in these populations. The frequency of the combined GSTM1 and GSTT1 null genotypes among Chinese, Malays and Indians were 37%, 22% and 5% respectively. The similarity with predicted frequencies indicated no interaction between the two genetic polymorphisms.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  13. Yaacob H, Nambiar P, Naidu MD
    Malays J Pathol, 1996 Jun;18(1):1-7.
    PMID: 10879216
    Determining the racial affinity of an unknown individual from dentition for identification is indeed a difficult endeavour. However, there are certain dental characteristics which are predominant in certain racial groups and these contribute important indicators in the identification process. Inherited dental characteristics are modified by prenatal and postnatal environmental and nutritional conditions. They can also become less discernible due to admixture of the various races.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  14. Roberts-Thomson PJ, Shepherd K, Bradley J, Boey ML
    Rheumatol Int, 1990;10(3):95-8.
    PMID: 2392640
    Low molecular weight IgM (LMW IgM) is the monomeric subunit of the naturally occurring pentameric IgM. It is not seen in health but has been previously observed in systemic lupus erythematosus (SLE) particularly in those patients with active disease and may reflect an adverse prognostic finding. We have therefore studied the presence of LMW IgM in 33 Chinese or Malay SLE patients (Singapore) and 21 Caucasian patients (Adelaide). LMW IgM was measured using filtration chromatography or by a sensitive immunoblotting technique. LMW IgM was observed in all patients in the Adelaide group and in 32 patients in the Singapore group with slightly greater quantities being seen in the Adelaide group. LMW IgM constituted up to 15.3% of the total IgM and was frequently associated with the presence of other low molecular weight IgM oligomers. In both groups LMW IgM correlated significantly with the total IgM levels (P less than 0.01). In a more detailed study in the Singapore group LMW IgM also correlated significantly with the IgM anticardiolipin levels (P = 0.02) but not with IgG anticardiolipin or with IgG or IgM anti-DNA levels or with rheumatoid factor. Patients with more extensive organ involvement had higher levels of LMW IgM but not at a significant level. We conclude that circulating LMW IgM occurs almost universally in SLE, is closely related to the total IgM levels and appears independent of ethnic background. The significance of LMW IgM in this disorder is unclear.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  15. Milne RL, Kuchenbaecker KB, Michailidou K, Beesley J, Kar S, Lindström S, et al.
    Nat Genet, 2017 Dec;49(12):1767-1778.
    PMID: 29058716 DOI: 10.1038/ng.3785
    Most common breast cancer susceptibility variants have been identified through genome-wide association studies (GWAS) of predominantly estrogen receptor (ER)-positive disease. We conducted a GWAS using 21,468 ER-negative cases and 100,594 controls combined with 18,908 BRCA1 mutation carriers (9,414 with breast cancer), all of European origin. We identified independent associations at P < 5 × 10-8 with ten variants at nine new loci. At P < 0.05, we replicated associations with 10 of 11 variants previously reported in ER-negative disease or BRCA1 mutation carrier GWAS and observed consistent associations with ER-negative disease for 105 susceptibility variants identified by other studies. These 125 variants explain approximately 16% of the familial risk of this breast cancer subtype. There was high genetic correlation (0.72) between risk of ER-negative breast cancer and breast cancer risk for BRCA1 mutation carriers. These findings may lead to improved risk prediction and inform further fine-mapping and functional work to better understand the biological basis of ER-negative breast cancer.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  16. Ambrose KK, Ishak T, Lian LH, Goh KJ, Wong KT, Ahmad-Annuar A, et al.
    BMJ Open, 2017 03 31;7(3):e010711.
    PMID: 28363916 DOI: 10.1136/bmjopen-2015-010711
    OBJECTIVE: The lack of epidemiological data and molecular diagnostic services in Malaysia has hampered the setting-up of a comprehensive management plan for patients with myotonic dystrophy type 1 (DM1), leading to delayed diagnosis, treatment and support for patients and families. The aim of this study was to estimate the prevalence of DM1 in the 3 major ethnic groups in Malaysia and evaluate the feasibility of a single tube triplet-primed PCR (TP-PCR) method for diagnosis of DM1 in Malaysia.

    DESIGN, SETTING AND PARTICIPANTS: We used PCR to determine the size of CTG repeats in 377 individuals not known to be affected by DM and 11 DM1 suspected patients, recruited from a tertiary hospital in Kuala Lumpur. TP-PCR was performed on selected samples, followed by Southern blot hybridisation of PCR amplified fragments to confirm and estimate the size of CTG expansion.

    OUTCOME MEASURES: The number of individuals not known to be affected by DM with (CTG)>18 was determined according to ethnic group and as a whole population. The χ2 test was performed to compare the distribution of (CTG)>18 with 12 other populations. Additionally, the accuracy of TP-PCR in detecting CTG expansion in 11 patients with DM1 was determined by comparing the results with that from Southern blot hybridisation.

    RESULTS: Of the 754 chromosomes studied, (CTG)>18 frequency of 3.60%, 1.57% and 4.00% in the Malay, Chinese and Indian subpopulations, respectively, was detected, showing similarities to data from Thai, Taiwanese and Kuwaiti populations. We also successfully detected CTG expansions in 9 patients using the TP-PCR method followed by the estimation of CTG expansion size via Southern blot hybridisation.

    CONCLUSIONS: The results show a low DM1 prevalence in Malaysia with the possibility of underdiagnosis and demonstrates the feasibility of using a clinical and TP-PCR-based approach for rapid and cost-effective DM1 diagnosis in developing countries.

    Matched MeSH terms: European Continental Ancestry Group/genetics
  17. Tai KY, Wong K, Aghakhanian F, Parhar IS, Dhaliwal J, Ayub Q
    BMC Genet, 2020 03 14;21(1):31.
    PMID: 32171244 DOI: 10.1186/s12863-020-0835-8
    BACKGROUND: Publicly available genome data provides valuable information on the genetic variation patterns across different modern human populations. Neuropeptide genes are crucial to the nervous, immune, endocrine system, and physiological homeostasis as they play an essential role in communicating information in neuronal functions. It remains unclear how evolutionary forces, such as natural selection and random genetic drift, have affected neuropeptide genes among human populations. To date, there are over 100 known human neuropeptides from the over 1000 predicted peptides encoded in the genome. The purpose of this study is to analyze and explore the genetic variation in continental human populations across all known neuropeptide genes by examining highly differentiated SNPs between African and non-African populations.

    RESULTS: We identified a total of 644,225 SNPs in 131 neuropeptide genes in 6 worldwide population groups from a public database. Of these, 5163 SNPs that had ΔDAF |(African - non-African)| ≥ 0.20 were identified and fully annotated. A total of 20 outlier SNPs that included 19 missense SNPs with a moderate impact and one stop lost SNP with high impact, were identified in 16 neuropeptide genes. Our results indicate that an overall strong population differentiation was observed in the non-African populations that had a higher derived allele frequency for 15/20 of those SNPs. Highly differentiated SNPs in four genes were particularly striking: NPPA (rs5065) with high impact stop lost variant; CHGB (rs6085324, rs236150, rs236152, rs742710 and rs742711) with multiple moderate impact missense variants; IGF2 (rs10770125) and INS (rs3842753) with moderate impact missense variants that are in linkage disequilibrium. Phenotype and disease associations of these differentiated SNPs indicated their association with hypertension and diabetes and highlighted the pleiotropic effects of these neuropeptides and their role in maintaining physiological homeostasis in humans.

    CONCLUSIONS: We compiled a list of 131 human neuropeptide genes from multiple databases and literature survey. We detect significant population differentiation in the derived allele frequencies of variants in several neuropeptide genes in African and non-African populations. The results highlights SNPs in these genes that may also contribute to population disparities in prevalence of diseases such as hypertension and diabetes.

    Matched MeSH terms: European Continental Ancestry Group/genetics
  18. Pan JW, Zabidi MMA, Ng PS, Meng MY, Hasan SN, Sandey B, et al.
    Nat Commun, 2020 Dec 22;11(1):6433.
    PMID: 33353943 DOI: 10.1038/s41467-020-20173-5
    Molecular profiling of breast cancer has enabled the development of more robust molecular prognostic signatures and therapeutic options for breast cancer patients. However, non-Caucasian populations remain understudied. Here, we present the mutational, transcriptional, and copy number profiles of 560 Malaysian breast tumours and a comparative analysis of breast cancers arising in Asian and Caucasian women. Compared to breast tumours in Caucasian women, we show an increased prevalence of HER2-enriched molecular subtypes and higher prevalence of TP53 somatic mutations in ER+ Asian breast tumours. We also observe elevated immune scores in Asian breast tumours, suggesting potential clinical response to immune checkpoint inhibitors. Whilst HER2-subtype and enriched immune score are associated with improved survival, presence of TP53 somatic mutations is associated with poorer survival in ER+ tumours. Taken together, these population differences unveil opportunities to improve the understanding of this disease and lay the foundation for precision medicine in different populations.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  19. Moriyama T, Yang YL, Nishii R, Ariffin H, Liu C, Lin TN, et al.
    Blood, 2017 Sep 07;130(10):1209-1212.
    PMID: 28659275 DOI: 10.1182/blood-2017-05-782383
    Prolonged exposure to thiopurines (eg, mercaptopurine [MP]) is essential for curative therapy in acute lymphoblastic leukemia (ALL), but is also associated with frequent dose-limiting hematopoietic toxicities, which is partly explained by inherited genetic polymorphisms in drug metabolizing enzymes (eg, TPMT). Recently, our group and others identified germ line genetic variants in NUDT15 as another major cause of thiopurine-related myelosuppression, particularly in Asian and Hispanic people. In this article, we describe 3 novel NUDT15 coding variants (p.R34T, p.K35E, and p.G17_V18del) in 5 children with ALL enrolled in frontline protocols in Singapore, Taiwan, and at St. Jude Children's Research Hospital. Patients carrying these variants experienced significant toxicity and reduced tolerance to MP across treatment protocols. Functionally, all 3 variants led to partial to complete loss of NUDT15 nucleotide diphosphatase activity and negatively influenced protein stability. In particular, the p.G17_V18del variant protein showed extremely low thermostability and was completely void of catalytic activity, thus likely to confer a high risk of thiopurine intolerance. This in-frame deletion was only seen in African and European patients, and is the first NUDT15 risk variant identified in non-Asian, non-Hispanic populations. In conclusion, we discovered 3 novel loss-of-function variants in NUDT15 associated with MP toxicity, enabling more comprehensive pharmacogenetics-based thiopurine dose adjustments across diverse populations.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  20. Beaty TH, Fallin MD, Hetmanski JB, McIntosh I, Chong SS, Ingersoll R, et al.
    Genetics, 2005 Sep;171(1):259-67.
    PMID: 15965248
    Analysis of haplotypes based on multiple single-nucleotide polymorphisms (SNP) is becoming common for both candidate gene and fine-mapping studies. Before embarking on studies of haplotypes from genetically distinct populations, however, it is important to consider variation both in linkage disequilibrium (LD) and in haplotype frequencies within and across populations, as both vary. Such diversity will influence the choice of "tagging" SNPs for candidate gene or whole-genome association studies because some markers will not be polymorphic in all samples and some haplotypes will be poorly represented or completely absent. Here we analyze 11 genes, originally chosen as candidate genes for oral clefts, where multiple markers were genotyped on individuals from four populations. Estimated haplotype frequencies, measures of pairwise LD, and genetic diversity were computed for 135 European-Americans, 57 Chinese-Singaporeans, 45 Malay-Singaporeans, and 46 Indian-Singaporeans. Patterns of pairwise LD were compared across these four populations and haplotype frequencies were used to assess genetic variation. Although these populations are fairly similar in allele frequencies and overall patterns of LD, both haplotype frequencies and genetic diversity varied significantly across populations. Such haplotype diversity has implications for designing studies of association involving samples from genetically distinct populations.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
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