Cytochrome P450 2E1 polymorphism and nasopharyngeal carcinoma development in Thailand: a correlative study.
BACKGROUND
Nasopharyngeal carcinoma (NPC) is a rare tumor in most parts of the world but occurs at relatively high frequency among people of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is responsible for the metabolic activation of nitrosamines, and has been shown to be a susceptibility gene for NPC development in Taiwan [RR = 2.6; 95%CI = 1.2-5.7]. Since there has been only one report of this link, it was decided to investigate the susceptibility of CYP2E1 to NPC development in other populations. Therefore, the correlation between the RsaI polymorphism of this gene and NPC was studied in-patients including Thai and Chinese in Thailand. The present study comprised 217 cases diagnosed with NPC and 297 healthy controls.


RESULTS
Similar to the result found in Taiwanese, a homozygous uncut genotype demonstrated a higher relative risk both when all cases were analyzed [RR = 2.19; 95%CI = 0.62-8.68] or individual racial groups, Thai [RR = 1.51; 95%CI = 0.08-90.06] or Chinese [RR = 1.99; 95%CI = 0.39-10.87]. The ethnicity-adjusted odds ratio is 2.39 with 95%CI, 0.72-7.89.


CONCLUSIONS
Though our finding was not statistically significant due to the moderate sample size of the study, similarity to the study in Taiwan with only a slight loss in precision was demonstrated. The higher RR found for the same genotype in distinct populations confirmed that CYP2E1 is one of several NPC susceptibility genes and that the RsaI minus variant is one mutation that affects phenotype.
Kongruttanachok
N
N
Genetics unit, Department of Anatomy, National Cancer Institute, Bangkok, Thailand. ruttiwan@hotmail.com
Sukdikul
S
S
Setavarin
S
S
Kerekhjanarong
V
V
Supiyaphun
P
P
Voravud
N
N
Poovorawan
Y
Y
Mutirangura
A
A
D044466:Asian People / Q000235:genetics; D002681:China / Q000208:ethnology; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics*; D005799:Genes, Dominant / Q000235:genetics; D005808:Genes, Recessive / Q000235:genetics; D006580:Genetic Carrier Screening; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005820:Genetic Testing / Q000379:methods; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D009303:Nasopharyngeal Neoplasms / Q000453:epidemiology* / Q000208:ethnology / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D012307:Risk Factors; D013785:Thailand / Q000453:epidemiology
D019392:Cytochrome P-450 CYP2E1