Displaying publications 1 - 20 of 72 in total

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  1. 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
  2. Saha N
    Hum. Hered., 1991;41(1):47-52.
    PMID: 2050382
    A total of 627 subjects comprising 455 Chinese, 127 Dravidian Indians and 45 Malays were investigated for serum Apo A-IV polymorphism. The frequency of Apo A-IV*2 was found to be significantly higher (p less than 0.001) in Indians (0.043) compared to that in the Chinese (0.010) and Malays (0.011). The frequency of A-IV*3 was found to be around 0.02 in all the ethnic groups. A low frequency of A-IV*4 (less than 0.01) was observed in the Chinese and Indians. The phenotypic distribution of Apo A-IV was at Hardy-Weinberg equilibrium in the three ethnic groups.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  3. 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
  4. 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
  5. 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*
  6. Zhao B, Lee EJ, Yeoh PN, Gong NH
    Pharmacogenetics, 1998 Aug;8(4):299-304.
    PMID: 9731716
    The xenobiotic metabolizing enzymes N-acetyltransferases (NATs) are important for the biotransformation and/or bioactivation of drugs and carcinogens. NATs are coded for in humans by two distinct genes, designated NAT1 and NAT2. NAT1, which was originally thought to be monomorphic, was recently reported to exhibit variation in human populations. Recent studies suggested that a genetic polymorphism of NAT1 may be associated with colorectal cancer risk. The distributions of NAT1 allele and genotype frequencies in unrelated individuals among Indian (n = 140), Malay (n = 122) and Chinese (n = 181) populations in Singapore were characterized by polymerase chain reaction-restriction fragment length polymorphism and allele-specific-polymerase chain reaction. The allelic frequencies of NAT1*3, NAT1*4, NAT1*10 and NAT1*11 among Indians were 0.3, 0.51, 0.17 and 0.02, respectively. The corresponding NAT1 allelic frequencies in Malays were 0.29, 0.30, 0.39 and 0.02, respectively, and were similar to those in Chinese in the region. The allelic frequencies of NAT1*3, NAT1*4, NAT1*10 and NAT1*11 among Chinese were 0.33, 0.35, 0.30 and 0.02, respectively. These findings are of importance for the determination of cancer risk in these populations. In addition, nucleotide changes at positions 350-351 (GG to CC) and 497-499 (GGG to CCC) of the NAT1 gene were not found in the alleles of the populations studied.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  7. Choong ML, Koay ES, Khaw MC, Aw TC
    Hum. Hered., 1999 Jan;49(1):31-40.
    PMID: 9858855
    The allele frequencies for the apolipoprotein B (apo B) 5'-Ins/Del and 3'-VNTR polymorphisms varied significantly (p < 0.01) among Singaporeans of Chinese, Malay and Indian descent. We calculated the unbiased expected heterozygosities for the 5'-Ins/Del polymorphism as 0.3357, 0.1984 and 0.2418, and for the 3'-VNTR as 0.5980, 0.5260 and 0.6749, respectively, in the Chinese, Malays and Indians. Compared to heterozygosities reported for other populations, the Singaporeans differed from most Caucasians in having significantly lower values but were closely related to other non-Caucasians. Thirteen alleles, with a bimodal distribution, were observed at the 3'-VNTR polymorphic locus; the alleles occurring most frequently among the Chinese and Malays were of 35 or 53 repeats, and among the Indians, of 37 or 47 repeats. The Del allele was associated with elevated serum cholesterol (p = 0.023), LDL-cholesterol (LDL-C) (p = 0.001) in the Chinese, and apo B (p = 0.007) in the Indians. Likewise, the larger 3'-VNTR alleles (> 41 repeats) were associated with raised cholesterol (p = 0.018), LDL-C (p = 0.025), and triglyceride (p = 0.001) in the Chinese. The two polymorphisms were not in significant linkage disequilibrium (D = -0.0029, p = 0.494) in the three ethnic groups.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  8. 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
  9. Halder D, Dharap AS, Than M
    Anthropol Anz, 1999 Mar;57(1):69-75.
    PMID: 10320927
    Early identification of a syndrome at birth is of paramount importance for genetic counselling and possible prevention. Often malformation of the hands and fingers are cardinal manifestations of recognizable syndromes. As there are no published standards for hand and finger size for Malay newborn infants, this study was undertaken to establish normal values for hand, middle finger and palmar lengths, and their indices. A cross-sectional study was done on 509 consecutive newborn Malay babies between 34 and 42 weeks of gestation. Measurements were made on the right hand according to the recommended guidelines of Bergsma & Feingold (1975). The mean values for the measurements did not differ significantly between boys and girls, or change with gestation. For the whole group the mean value for total hand length was 64.4 +/- 3.42 mm, middle finger length 37.1 +/- 2.91 mm, palmar length 27.4 +/- 2.15 mm, finger index 0.425 +/- 0.03 and palmar index 0.58 +/- 0.03. A comparison with published measurements for newborns of different racial origin shows significant differences for the total hand length, middle finger length and palm length from Indian and Jewish infants, but not from Japanese infants. The indices were similar in Malay, Indian, Jewish and Japanese newborn infants.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  10. 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*
  11. 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
  12. 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*
  13. Ismail R, Teh LK
    Eur J Clin Pharmacol, 2001 Oct;57(8):617-8.
    PMID: 11758642
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  14. Tan JH, Low PS, Tan YS, Tong MC, Saha N, Yang H, et al.
    Hum Genet, 2003 Jul;113(2):106-17.
    PMID: 12709788
    Mutations in the ATP-binding cassette transporter ABCA1 underlie Tangier disease and familial hypoalphaliproteinemia (FHA), disorders that are characterised by reduced high-density lipoprotein-cholesterol (HDL-C) concentration and cholesterol efflux, and increased coronary artery disease (CAD). We explored if polymorphisms in the ABCA1 gene are associated with CAD and variations in plasma lipid levels, especially HDL-C, and whether the associations may depend on ethnicity. Male cases and controls from the Singapore Chinese, Malay and Indian populations were genotyped for five ABCA1 single nucleotide polymorphisms. Various single-locus frequency distribution differences between cases and controls were detected in different ethnic groups: the promoter -14C>T in Indians, exon 18 M883I in Malays, and 3'-untranslated (UTR) region 8994A>G in Chinese. For the Malay population, certain haplotypes carrying the I825- A (exon 17) and M883- G alleles were more frequent among cases than controls, whereas the converse was true for the alternative configuration of V825- G and I883- A, and this association was reinforced in multi-locus disequilibrium analysis that utilized genotypic data. In the healthy controls, associations were found for -14C>T genotypes with HDL-C in Chinese; 237indelG (5'UTR) with apolipoprotein A1 (apoA1) in Malays and total cholesterol (TC) in Indians; M883I with lipoprotein(a) [Lp(a)] in Malays and apolipoprotein B (apoB) in Chinese; and 8994A>G with Lp(a) in Malays, and TC, low-density lipoprotein-cholesterol (LDL-C) as well as apoB in Indians. While genotype-phenotype associations were not reproduced across populations and loci, V825I and M883I were clearly associated with CAD status in Malays with no effects on HDL-C or apoA1.
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  15. 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*
  16. Zainuddin Z, Teh LK, Suhaimi AW, Ismail R
    J Clin Pharm Ther, 2006 Apr;31(2):187-91.
    PMID: 16635054
    CYP2C9 is one of the major drug metabolizing enzymes for many drugs including warfarin, NSAIDs and losartan. It is polymorphic in many populations. Data on the distribution of CYP2C9 and the implication of CYP2C9 polymorphism in the Malaysian population is lacking. Our objectives were therefore to investigate the prevalence of CYP2C9 variants among unrelated healthy volunteers of Malays, Chinese and Indians in Malaysia.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  17. 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
  18. Ismail R
    J Postgrad Med, 2006 Oct-Dec;52(4):245.
    PMID: 17243206
    Matched MeSH terms: European Continental Ancestry Group/genetics*
  19. Chang YM, Perumal R, Keat PY, Yong RY, Kuehn DL, Burgoyne L
    Forensic Sci Int, 2007 Mar 2;166(2-3):115-20.
    PMID: 16765004
    The use of STR multiplexes with the incorporated gender marker Amelogenin is common practice in forensic DNA analysis. However, when a known male sample shows a dropout of the Amelogenin Y-allele, the STR system falsely genotypes it as a female. To date, our laboratory has observed 18 such cases: 12 from our Y-STR database and six from casework. A study on 980 male individuals in the Malaysian population using the AmpFlSTR Y-filer has revealed a distinct Y-chromosome haplotype associated with the Amelogenin nulls. Our results showed that whilst the Amelogenin nulls were noticeably absent among the Chinese, both the Indians and Malays exhibited such mutations at 3.2 and 0.6%, respectively. It was also found that the Amelogenin negative individuals predominantly belonged to the J2e lineage, suggesting the possibility of a common ancestor for at least some of these chromosomes. The null frequencies showed concordance with the data published in Chang et al. [Higher failures of Amelogenin sex test in an Indian population group, J. Forensic Sci. 48 (2003) 1309-1313] on a smaller Malaysian population of 338 males which used a Y-STR triplex. In the current study, apart from the absence of the Amelogenin Y-locus, a complete absence of the DYS458 locus in all the nulls was also observed. This study together with the 2003 study has indicated a similar deletion region exists on the Y(p)11.2 band in all the 18 Y-chromosomes. Using bioinformatics, this deletion has been mapped to a region of at least 1.13 Mb on the Y(p)11.2 encompassing the Amelogenin, MSY1 minisatellite and DYS458 locus. Further, the Y-filer haplotypes revealed an additional null at Y-GATA H4 in two of the Indian males presented here.
    Matched MeSH terms: European Continental Ancestry Group/genetics
  20. 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
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