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  1. Obesity and genomics: role of technology in unraveling the complex genetic architecture of obesity
    Apalasamy YD, Mohamed Z
    Hum Genet, 2015 Apr;134(4):361-74.
    PMID: 25687726 DOI: 10.1007/s00439-015-1533-x
    Obesity is a complex and multifactorial disease that occurs as a result of the interaction between "obesogenic" environmental factors and genetic components. Although the genetic component of obesity is clear from the heritability studies, the genetic basis remains largely elusive. Successes have been achieved in identifying the causal genes for monogenic obesity using animal models and linkage studies, but these approaches are not fruitful for polygenic obesity. The developments of genome-wide association approach have brought breakthrough discovery of genetic variants for polygenic obesity where tens of new susceptibility loci were identified. However, the common SNPs only accounted for a proportion of heritability. The arrival of NGS technologies and completion of 1000 Genomes Project have brought other new methods to dissect the genetic architecture of obesity, for example, the use of exome genotyping arrays and deep sequencing of candidate loci identified from GWAS to study rare variants. In this review, we summarize and discuss the developments of these genetic approaches in human obesity.
  2. Fulltext Genetic associations of the INSIG2 rs7566605 polymorphism with obesity-related metabolic traits in Malaysian Malays
    Apalasamy YD, Moy FM, Rampal S, Bulgiba A, Mohamed Z
    Genet. Mol. Res., 2014;13(3):4904-10.
    PMID: 25062423 DOI: 10.4238/2014.July.4.4
    A genome-wide association study showed that the tagging single nucleotide polymorphism (SNP) rs7566605 in the insulin-induced gene 2 (INSIG2) was associated with obesity. Attempts to replicate this result in different populations have produced inconsistent findings. We aimed to study the association between the rs7566605 SNP with obesity and other metabolic parameters in Malaysian Malays. Anthropometric and obesity-related metabolic parameters and DNA samples were collected. We genotyped the rs7566605 polymorphism in 672 subjects using real-time polymerase chain reaction. No significant associations were found between the rs7566605 tagging SNP of INSIG2 with obesity or other metabolic parameters in the Malaysian Malay population. The INSIG2 rs7566605 SNP may not play a role in the development of obesity-related metabolic traits in Malaysian Malays.
  3. Genetic association of SNPs in the FTO gene and predisposition to obesity in Malaysian Malays
    Apalasamy YD, Ming MF, Rampal S, Bulgiba A, Mohamed Z
    Braz. J. Med. Biol. Res., 2012 Dec;45(12):1119-26.
    PMID: 22911346
    The common variants in the fat mass- and obesity-associated (FTO) gene have been previously found to be associated with obesity in various adult populations. The objective of the present study was to investigate whether the single nucleotide polymorphisms (SNPs) and linkage disequilibrium (LD) blocks in various regions of the FTO gene are associated with predisposition to obesity in Malaysian Malays. Thirty-one FTO SNPs were genotyped in 587 (158 obese and 429 non-obese) Malaysian Malay subjects. Obesity traits and lipid profiles were measured and single-marker association testing, LD testing, and haplotype association analysis were performed. LD analysis of the FTO SNPs revealed the presence of 57 regions with complete LD (D' = 1.0). In addition, we detected the association of rs17817288 with low-density lipoprotein cholesterol. The FTO gene may therefore be involved in lipid metabolism in Malaysian Malays. Two haplotype blocks were present in this region of the FTO gene, but no particular haplotype was found to be significantly associated with an increased risk of obesity in Malaysian Malays.
  4. Gender-dependent association of a β(2)-adrenergic gene variant with obesity parameters in Malaysian Malays
    Apalasamy YD, Ming MF, Rampal S, Bulgiba A, Mohamed Z
    Asia Pac J Public Health, 2015 Mar;27(2):NP154-65.
    PMID: 22199155 DOI: 10.1177/1010539511430250
    Recent findings have shown that the rs1042714 (Gln27Glu) single-nucleotide polymorphism (SNP) on the β2-adrenoceptor gene may predispose to obesity. The findings from other studies carried on different populations, however, have been inconsistent. The authors investigated the association between the rs1042714 SNP with obesity-related parameters. DNA of 672 Malaysian Malays was analyzed using real-time polymerase chain reaction. Univariate and multivariate linear regression analyses revealed significant associations between rs1042714 and diastolic blood pressure in the pooled Malaysian Malay subjects under additive and recessive models. After gender stratification, however, a significant association was found between the rs1042714 and triglyceride and the rs1042714 and log-transformed high-density lipoprotein cholesterol levels in Malaysian Malay men. No significant association was found between the SNP and log-transformed body mass index. This polymorphism may have an important role in the development of obesity-related traits in Malaysian Malays. Gender is an effect modifier for the effect of the rs1042714 polymorphism on obesity-related traits in Malaysian Malays.
  5. Genetic association of AKAP10 gene polymorphism with reduced risk of preterm birth
    Langmia IM, Apalasamy YD, Suki SZ, Omar SZ, Mohamed Z
    J Perinatol, 2015 Sep;35(9):700-4.
    PMID: 26110499 DOI: 10.1038/jp.2015.68
    Preterm birth (PTB) is a multifactorial complication in which genetic and environmental factors contribute to the phenotype. The AKAP10 protein encoded by AKAP10 gene has a vital role in the maintenance of myometrial quiescence and pregnancy. This study aimed to investigate whether polymorphisms in the AKAP10 gene are associated with the risk of PTB.
  6. Fulltext Interleukin-6 gene variants are associated with reduced risk of chronicity in hepatitis B virus infection in a Malaysian population
    Riazalhosseini B, Mohamed Z, Apalasamy YD, Shafie NS, Mohamed R
    Biomed Rep, 2018 Sep;9(3):213-220.
    PMID: 30271596 DOI: 10.3892/br.2018.1126
    Interleukin-6 (IL-6) is a cytokine with a critical role in regulating the immune response to infectious disease. Studies have indicated that polymorphisms in the IL-6 gene may be linked to hepatitis B virus (HBV) infection. The purpose of the present study was to examine the association among IL-6 SNPs and haplotypes with HBV infection risk in a Malaysian population. A total of 1,246 Malaysian subjects with and without chronic hepatitis B were recruited for this study. Three IL-6 polymorphisms (rs2069837, rs1800796 and rs2066992) were genotyped using a Sequenom MassARRAY® platform. The results suggested that GC and CC genotypes of rs1800796 as well as GT and TT genotypes of rs2066992 were associated with protection against HBV infection (P<0.001). Furthermore, haplotypes GG and CT exhibited a significant association with protection against HBV (P=0.003 and =0.005, respectively); and haplotypes GG and CT exhibited a significant association with clearance of HBV infection (P=0.035 and =0.037, respectively). The present study indicates that two IL-6 SNPs (rs1800796 and rs2066992) are associated with clearance of chronic HBV or protection against HBV infection at allelic, genotypic and haplotypic levels.
  7. Association between microRNA-196A2 and microRNA-146A polymorphisms and progression to cirrhosis and hepatocellular carcinoma in patients with viral hepatitis B
    Riazalhosseini B, Mohamed Z, Apalasamy YD, Eng HS, Mohamed R
    Pharmacogenet Genomics, 2016 Feb;26(2):74-9.
    PMID: 26529280 DOI: 10.1097/FPC.0000000000000187
    MicroRNAs (miRNAs) are small noncoding RNAs that have been implicated in mechanisms underlying various types of cancers including hepatocellular carcinoma (HCC). Reports have indicated that single nucleotide polymorphisms in miRNA-196A2 and miRNA-146A genes may contribute to the risk of progression of hepatitis B virus (HBV) infection to cirrhosis and HCC. This study aimed to examine the effect of miRNA-196A2 and miRNA-146A polymorphisms on the progression of HBV infection to cirrhosis and/or HCC in HBV patients in the Malaysian population.
  8. Association of VEGFA gene polymorphisms and VEGFA plasma levels with spontaneous preterm birth
    Langmia IM, Apalasamy YD, Omar SZ, Mohamed Z
    Pharmacogenet Genomics, 2015 Apr;25(4):199-204.
    PMID: 25714003 DOI: 10.1097/FPC.0000000000000125
    Angiogenic pathway regulating genes such as vascular endothelial growth factor A (VEGFA) have been implicated in preterm birth (PTB) complications. Research shows that the VEGFA/VEGF receptor system plays an important role in the regulation of circulating progesterone level. Attenuation of VEGFA signaling at mid pregnancy results in onset of labor and parturition because of a reduction in circulating progesterone levels. The aim of this study was to investigate the association of VEGFA gene polymorphisms (rs2010963, rs3025039, rs699947, and rs10434) with spontaneous PTB and VEGFA plasma levels in preterm and term women.
  9. Impact of IL1B gene polymorphisms and interleukin 1B levels on susceptibility to spontaneous preterm birth
    Langmia IM, Apalasamy YD, Omar SZ, Mohamed Z
    Pharmacogenet Genomics, 2016 Nov;26(11):505-509.
    PMID: 27602547
    OBJECTIVE: Genetic factors influence susceptibility to preterm birth (PTB) and the immune pathway of PTB that involves the production of cytokines such as interleukins has been implicated in PTB disease. The aim of this study is to investigate the association of interleukin 1β (IL1B) gene polymorphisms and IL1B levels with spontaneous PTB.

    STUDY DESIGN: Peripheral maternal blood from 495 women was used for extraction of DNA and genotyping was carried out using the Sequenom MassARRAY platform. Maternal plasma was used to measure IL1B levels.

    RESULTS: There was no significant association between the allelic and genotype distribution of IL1B single nucleotide polymorphism (SNP) (rs1143634, rs1143627, rs16944) and the risk of PTB among Malaysian Malay women (rs1143634, P=0.722; rs1143627, P=0.543; rs16944, P=0.615). However, IL1B levels were significantly different between women who delivered preterm compared with those who delivered at term (P=0.030); high mean levels were observed among Malay women who delivered at preterm (mean=32.52) compared with term (mean=21.68). IL1B SNPs were not associated with IL1B plasma levels.

    CONCLUSION: This study indicates a significant association between IL1B levels and reduced risk of PTB among the Malaysian Malay women. This study shows the impact of IL1B levels on susceptibility to PTB disease; however, the high levels of IL1B observed among women in the preterm group are not associated with IL1B SNPs investigated in this study; IL1B high levels may be because of other factors not explored in this study and therefore warrant further investigation.

  10. Interleukin 1 receptor type 2 gene polymorphism is associated with reduced risk of preterm birth
    Langmia IM, Apalasamy YD, Omar SZ, Mohamed Z
    J Matern Fetal Neonatal Med, 2015 Dec 23.
    PMID: 26607028
    Interleukin 1 receptor type 2 (IL1R2) regulates the inflammatory pathway that results in preterm delivery. We aim to investigate the impact of IL1R2 gene polymorphisms on the risk of preterm delivery.
  11. Fulltext Circulating microRNA as a marker for predicting liver disease progression in patients with chronic hepatitis B
    Riazalhosseini B, Mohamed R, Apalasamy YD, Langmia IM, Mohamed Z
    Rev Soc Bras Med Trop, 2017 Mar-Apr;50(2):161-166.
    PMID: 28562750 DOI: 10.1590/0037-8682-0416-2016
    INTRODUCTION: Hepatitis B virus (HBV) constitutes an important risk factor for cirrhosis and hepatocellular carcinoma (HCC). The link between circulating microRNAs and HBV has been previously reported, although not as a marker of liver disease progression in chronic hepatitis B (CHB). The aim of this study was to characterize miRNA expression profiles between CHB with and without cirrhosis or HCC.

    METHODS:: A total of 12 subjects were recruited in this study. We employed an Affymetrix Gene Chip miRNA 3.0 Array to provide universal miRNA coverage. We compared microRNA expression profiles between CHB with and without cirrhosis/HCC to discover possible prognostic markers associated with the progression of CHB.

    RESULTS:: Our results indicated 8 differently expressed microRNAs, of which miRNA-935, miRNA-342, miRNA-339, miRNA-4508, miRNA-3615, and miRNA-3200 were up-regulated, whereas miRNA-182 and miRNA-4485 were down-regulated in patients with CHB who progressed to cirrhosis/HCC as compared to those without progression.

    CONCLUSIONS:: We demonstrated the differential expression of miRNA-935, miRNA-342, miRNA-339, miRNA-4508, miRNA-3615, miRNA-3200, miRNA-182, and miRNA-4485 between patients with HBV without cirrhosis/HCC and those who had progressed to these more severe conditions. These miRNAs may serve as novel and non-invasive prognostic markers for early detection of CHB-infected patients who are at risk of progression to cirrhosis and/or HCC.
  12. Association of melanocortin-4 receptor gene polymorphisms with obesity-related parameters in Malaysian Malays
    Apalasamy YD, Ming MF, Rampal S, Bulgiba A, Mohamed Z
    Ann Hum Biol, 2013 Jan;40(1):102-6.
    PMID: 22989167 DOI: 10.3109/03014460.2012.720709
    Melanocortin-4 receptor (MC4R) is an important regulator of body weight and energy intake. Genetic polymorphisms of the MC4R gene have been found to be linked to obesity in many recent studies across the globe.
  13. Fulltext Progesterone Receptor (PGR) gene polymorphism is associated with susceptibility to preterm birth
    Langmia IM, Apalasamy YD, Omar SZ, Mohamed Z
    BMC Med Genet, 2015;16:63.
    PMID: 26286601 DOI: 10.1186/s12881-015-0202-1
    Preterm birth (PTB) is the major cause of death in newborn and the second major cause of death in children less than 5 years old worldwide. Genetic polymorphism has been implicated as a factor for the occurrence of preterm birth. The aim of this study is to evaluate whether polymorphism in the progesterone receptor (PGR) is associated with susceptibility to preterm birth.
  14. Association of ADIPOQ gene with obesity and adiponectin levels in Malaysian Malays
    Apalasamy YD, Rampal S, Salim A, Moy FM, Bulgiba A, Mohamed Z
    Mol Biol Rep, 2014 May;41(5):2917-21.
    PMID: 24449366 DOI: 10.1007/s11033-014-3147-0
    Studies have shown that single-nucleotide polymorphisms (SNPs) on the ADIPOQ gene have been linked with obesity and with adiponectin levels in various populations. Here, we aimed to investigate the association of ADIPOQ rs17366568 and rs3774261 SNPs with obesity and with adiponectin levels in Malaysian Malays. Obesity parameters and adiponectin levels were measured in 574 subjects. Genotyping was performed using real-time polymerase chain reaction and Sequenom MassARRAY. A significant genotypic association was observed between ADIPOQ rs17366568 and obesity. The frequencies of AG and AA genotypes were significantly higher in the obese group (11%) than in the non-obese group (5%) (P=0.024). The odds of A alleles occurring among the obese group were twice those among the non-obese group (odds ratio 2.15; 95% confidence interval 1.13-4.09). However, no significant association was found between allelic frequencies of ADIPOQ rs17366568 and obesity after Bonferroni correction (P>0.025) or between ADIPOQ rs3774261 and obesity both at allelic and genotypic levels. ADIPOQ SNPs were not significantly associated with log-adiponectin levels. GA, GG, and AG haplotypes of the ADIPOQ gene were not associated with obesity. We confirmed the previously reported association of ADIPOQ rs17366568 with the risk of obesity. ADIPOQ SNPs are not important modulators of adiponectin levels in this population.
  15. Genetic polymorphisms in the androgen metabolism pathway and risk of prostate cancer in low incidence Malaysian ethnic groups
    Poniah P, Mohamed Z, Apalasamy YD, Mohd Zain S, Kuppusamy S, Razack AH
    Int J Clin Exp Med, 2015;8(10):19232-40.
    PMID: 26770559
    Androgens are involved in prostate cancer (PCa) cell growth. Genes involved in androgen metabolism mediate key steps in sex steroid metabolism. This study attempted to investigate whether single nucleotide polymorphisms (SNPs) in the androgen metabolism pathway are associated with PCa risk in low incidence Asian ethnic groups. We genotyped 172 Malaysian subjects for cytochrome P450 family 17 (CYP17A1), steroid-5-alpha-reductase, polypeptide 1 and 2 (SRD5A1 and SRD5A2), and insulin-like growth factor 1 (IGF-1) genes of the androgen metabolism pathway and assessed the testosterone, dihydrotestosterone and IGF-1 levels. SNPs in the CYP17A1, SRD5A1, SRD5A2, and IGF-1 genes were genotyped using real-time polymerase chain reaction. Although we did not find significant association between SNPs analysed in this study with PCa risk, we observed however, significant association between androgen levels and the IGF-1 and several SNPs. Men carrying the GG genotype for SNP rs1004467 (CYP17A1) had significantly elevated testosterone (P = 0.012) and dihydrotestosterone (DHT) levels (P = 0.024) as compared to carriers of the A allele. The rs518673 of the SRD5A1 was associated with prostate specific antigen (PSA) levels. Our findings suggest CYP17A1 rs1004467 SNP is associated with testosterone and DHT levels indicating the importance of this gene in influencing androgen levels in the circulatory system of PCa patients, hence could be used as a potential marker in PCa assessment.
  16. Polymorphisms of the resistin gene and their association with obesity and resistin levels in Malaysian Malays
    Apalasamy YD, Rampal S, Salim A, Moy FM, Su TT, Majid HA, et al.
    Biochem Genet, 2015 Jun;53(4-6):120-31.
    PMID: 25991560 DOI: 10.1007/s10528-015-9678-9
    Single nucleotide polymorphisms (SNP) in the resistin gene (RETN) are linked to obesity and resistin levels in various populations. However, results have been inconsistent. This study aimed to investigate association between polymorphisms in the resistin gene with obesity in a homogenous Malaysian Malay population. This study is also aimed to determine association between resistin levels with certain SNPs and haplotypes of RETN. A total of 631 Malaysian Malay subjects were included in this study and genotyping was carried out using Sequenom MassARRAY. There was no significant difference found in both allelic and genotype frequencies of each of the RETN SNPs between the obese and non-obese groups after Bonferroni correction. RETN rs34861192 and rs3219175 SNPs were significantly associated with log-resistin levels. The GG genotype carriers are found to have higher levels of log-resistin compared to A allele carriers. The RETN haplotypes (CAG, CGA and GA) were significantly associated with resistin levels. However, the haplotypes of the RETN gene were not associated with obesity. Resistin levels were not correlated to metabolic parameters such as body weight, waist circumference, body mass index, and lipid parameters. RETN SNPs and haplotypes are of apparent functional importance in the regulation of resistin levels but are not correlated with obesity and related markers.
  17. Factors Associated With Obesity and Abdominal Obesity Among Malaysian Older Adults
    Apalasamy YD, Awang H, Mansor N, AbRashid N, Kamarulzaman ND, Lih Yoong T
    Asia Pac J Public Health, 2021 07;33(5):547-554.
    PMID: 34013778 DOI: 10.1177/10105395211014634
    Obesity is a rising concern globally. This study investigated the prevalence and factors associated with obesity and abdominal obesity (AO) among 5613 Malaysians aged 40 years and older via computer-assisted personal interviewing and anthropometric measurements. Obesity and AO prevalence were 37.8% and 63.1%, respectively. Significant associations were observed between: obesity with higher risk in patients aged between 40 and 49 years, Indians, females, income ≥RM 2000, and health status, and AO with higher risk in patients aged between 50 and 59 years, Indians, females, never married, income ≥RM 2000, and vigorous physical activity. Hence, age, sex, income, and ethnicity are associated with both obesity and AO. Promoting healthy body mass index and waist circumference is essential for healthy ageing.
  18. Fulltext Is universal HLA-B*15:02 screening a cost-effective option in an ethnically diverse population? A case study of Malaysia
    Chong HY, Mohamed Z, Tan LL, Wu DBC, Shabaruddin FH, Dahlui M, et al.
    Br J Dermatol, 2017 Oct;177(4):1102-1112.
    PMID: 28346659 DOI: 10.1111/bjd.15498
    BACKGROUND: A strong association has been documented between HLA-B*15:02 and carbamazepine-induced severe cutaneous adverse reactions (SCARs) in Asians. Human leucocyte antigen testing is potentially valuable in many countries to facilitate early recognition of patient susceptibility to SCARs.

    OBJECTIVES: To determine the cost-effectiveness of universal HLA-B*15:02 screening in preventing carbamazepine-induced Stevens-Johnson syndrome/toxic epidermal necrolysis in an ethnically diverse Malaysian population.

    METHODS: A hybrid model of a decision tree and Markov model was developed to evaluate three strategies for treating newly diagnosed epilepsy among adults: (i) carbamazepine initiation without HLA-B*15:02 screening (current practice); (ii) universal HLA-B*15:02 screening prior to carbamazepine initiation; and (iii) alternative treatment [sodium valproate (VPA)] prescribing without HLA-B*15:02 screening. Base-case analysis and sensitivity analyses were performed over a lifetime time horizon. Incremental cost-effectiveness ratios were calculated.

    RESULTS: Both universal HLA-B*15:02 screening and VPA prescribing were dominated by current practice. Compared with current practice, universal HLA-B*15:02 screening resulted in a loss of 0·0255 quality-adjusted life years (QALYs) at an additional cost of 707 U.S. dollars (USD); VPA prescribing resulted in a loss of 0·2622 QALYs at an additional cost of USD 4127, owing to estimated differences in antiepileptic treatment efficacy.

    CONCLUSIONS: Universal HLA-B*15:02 screening is unlikely to be a cost-effective intervention in Malaysia. However, with the emergence of an ethnically diverse population in many other countries, this may render HLA-B*15:02 screening a viable intervention when an increasing proportion of the population is at risk and an equally effective yet safer antiepileptic drug is available.

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