RESUMO
BACKGROUND: CYP3A5 is the predominant sub-family of biotransformation enzymes in the liver and the genetic variations in CYP3A5 are an important determinant of inter-individual and inter-ethnic differences in CYP3A-mediated drug disposition and response. AIM: This study aims to investigate the genetic polymorphisms of CYP3A5 among the Orang Asli in Peninsular Malaysia using a next generation sequencing platform. METHODS: Genomic DNAs were extracted from blood samples of the three main Orang Asli tribes and whole-genome sequencing was performed. RESULTS: A total of 61 single nucleotide polymorphisms were identified and all the SNPs were located in introns except rs15524, which is in the 3'UTR, and 11 of these polymorphisms were novel. Two allelic variants and three genotypes were identified in the Orang Asli. The major allelic variant was the non-functional CYP3A5*3 (66.4%). The percentages of Orang Asli with CYP3A5*3/*3 (47.2%) and CYP3A5*1/*3 (38.1%) genotypes are more than twice the percentage of Orang Asli with CYP3A5*1/*1 (14.8%) genotype. Almost half of the Orang Asli harboured CYP3A5 non-expressor genotype (CYP3A5*3/*3). CONCLUSIONS: The predominance of the CYP3A5 non-expressor genotype among the Orang Asli was unravelled and the findings in this study may serve as a guide for the optimisation of pharmacotherapy for the Orang Asli community.
Assuntos
Citocromo P-450 CYP3A/genética , Etnicidade/genética , Frequência do Gene , Polimorfismo de Nucleotídeo Único , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , MalásiaRESUMO
BACKGROUND: Despite the strategic development plan by the authorities for the Orang Asli, there are six subtribes of which their population numbers are small (less than 700). These minorities were not included in most of the health related studies published thus far. A comprehensive physiological and biomedical updates on these small subtribes in comparison to the larger subtribes and the urban Malay population is timely and important to help provide appropriate measures to prevent further reduction in the numbers of the Orang Asli. METHODS: A total of 191 Orang Asli from different villages in Peninsular Malaysia and 115 healthy urban Malays were recruited. Medical examinations and biochemical analyses were conducted. Framingham risk scores were determined. Data was analyzed using IBM SPSS Statistics, Version 20.0. RESULTS: A higher percentage of the Orang Asli showed high insulin levels and hsCRP compared to the healthy Malays denoting possible risk of insulin resistance. High incidences of low HDL-c levels were observed in all the Orang Asli from the six subtribes but none was detected among the urban Malays. A higher percentage of inlanders (21.1% of the males and 4.2% of the females) were categorized to have high Framingham Risk Score. CONCLUSIONS: Orang Asli staying both in the inlands and peripheries are predisposed to cardiovascular diseases and insulin resistance diabetes mellitus. The perception of Orang Asli being healthier than the urban people no longer holds. We believed that this information is important to the relevant parties in strategizing a healthier community of the Orang Asli to avoid the vanishing of the vulnerable group(s).
Assuntos
Doenças Cardiovasculares/etnologia , Resistência à Insulina/etnologia , Adolescente , Adulto , Proteína C-Reativa/análise , HDL-Colesterol/sangue , Feminino , Humanos , Malásia/epidemiologia , Masculino , Pessoa de Meia-Idade , Fatores de Risco , População Rural , Distribuição por Sexo , População Urbana , Adulto JovemRESUMO
The human cytochrome P450 (CYP) is a superfamily of enzymes that have been a focus in research for decades due to their prominent role in drug metabolism. CYP2C is one of the major subfamilies which metabolize more than 10% of all clinically used drugs. In the context of CYP2C19, several key genetic variations that alter the enzyme's activity have been identified and catalogued in the CYP allele nomenclature database. In this study, we investigated the presence of well-established variants as well as novel polymorphisms in the CYP2C19 gene of 62 Orang Asli from the Peninsular Malaysia. A total of 449 genetic variants were detected including 70 novel polymorphisms; 417 SNPs were located in introns, 23 in upstream, 7 in exons, and 2 in downstream regions. Five alleles and seven genotypes were inferred based on the polymorphisms that were found. Null alleles that were observed include CYP2C19*3 (6.5%), *2 (5.7%) and *35 (2.4%) whereas allele with increased function *17 was detected at a frequency of 4.8%. The normal metabolizer genotype was the most predominant (66.1%), followed by intermediate metabolizer (19.4%), rapid metabolizer (9.7%) and poor metabolizer (4.8%) genotypes. Findings from this study provide further insights into the CYP2C19 genetic profile of the Orang Asli as previously unreported variant alleles were detected through the use of massively parallel sequencing technology platform. The systematic and comprehensive analysis of CYP2C19 will allow uncharacterized variants that are present in the Orang Asli to be included in the genotyping panel in the future.
Assuntos
Povo Asiático/genética , Citocromo P-450 CYP2C19/genética , Variação Genética , Sequenciamento de Nucleotídeos em Larga Escala , Adolescente , Adulto , Idoso , Alelos , Feminino , Genótipo , Haplótipos , Humanos , Desequilíbrio de Ligação , Malásia , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , Adulto JovemRESUMO
We conducted a systematic characterization of CYP2C9 variants in 61 Orang Asli and 96 Singaporean Malays using the whole genome sequences data and compared the variants with the other 11 HapMap populations. The frequency of rs1057910 (CYP2C9*3) is the highest in the Orang Asli compared to other populations. Three alleles with clinical implication were detected in the Orang Asli while 2 were found in the Singaporean Malays. Large numbers of the Orang Asli are predicted to have reduced metabolic capacity and therefore they would require a lower dose of drugs which are metabolized by CYP2C9. They are also at increased risks of adverse effects and therapeutic failures. A large number of CYP2C9 variants in the Orang Asli were not in the Hardy Weinberg Equilibrium which could be due to small sample size or mutations that disrupt the equilibrium of allele frequencies. In conclusion, different polymorphism patterns, allele frequencies, genotype frequencies and LD blocks are observed between the Orang Asli, the Singaporean Malays and the other populations. The study provided new information on the genetic polymorphism of CYP2C9 which is important for the implementation of precision medicine for the Orang Asli.