[Study on the relationship between polymorphism of insulin-receptor gene EXON2-2257 and insulin resistance in Chinese people].
OBJECTIVE
To understand the role of insulin-receptor gene in the development of insulin resistance on a population-based study in China.


METHODS
Polymerase chain reaction (PCR) was used to amplify the EXON2 of the insulin-receptor gene and all amplified products were analyzed by direct sequencing.


RESULTS
Three genotypes of single nucleotide at the site of 2257 in EXON2 of the insulin-receptor gene were identified. In 237 of the 345 cases (68.7%), homozygote genotype of CC phenotype was found with a gene frequency of 0.825; 13 cases (3.77%) showed homozygote genotype of TT phenotype with a gene frequency of 0.175 and the rest 95 cases (27.54%) showed heterozygote genotype of CT phenotype. Data were in agreement with the test of Hardy-Weinberg balance (chi(2) = 0.2898, upsilon = 3 - 2 = 1, 0.5 < P < 0.75). The serum level of triglyceride and the HOMA-IR index, the status of insulin resistance assessed by homeostasis model assessment (HOMA), were lower in the TT or CT genotype group than that in the CC genotype group (P < 0.05). Comparing with CC genotype, the proportion of CT genotype (18.4%) in the insulin resistance group (large than 75th percentile of HOMA-IR) was significantly lower than that in the control group (30.6%) (P = 0.022, OR = 0.493). The proportion of TT genotype (2.3%) in insulin resistance group was lower than that in the control group (4.3%, P = 0.297). logistic analysis revealed that after adjusting possible confounding factors such as taking anti-hypertensive and anti-diabetic medications, serum triglyceride and high density lipoprotein cholesterol (HDL-C), hypertension, BMI, smoking history, the OR value of people in the insulin resistance group with CT genotype was 0.448 (95% CI: 0.214 to 0.940) compared to the group with CC genotype.


CONCLUSIONS
The hybridization CT genotype at the site of 2257 in EXON2 of insulin-receptor gene might have a candidate gene to serve as a protective factor for insulin resistance.
Wang
Lu
L
Department of Epidemiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, School of Basic Medicine, Peking Union Medical College, Beijing 100005, China.
Mi
Jie
J
Wu
Jian-xin
JX
Zhao
Xiao-yuan
XY
Cheng
Hong
H
Ding
Xiu-yuan
XY
Hou
Dong-qing
DQ
Lu
Jie
J
Gu
Xue
X
D000328:Adult; D002681:China; D005091:Exons / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007333:Insulin Resistance / Q000235:genetics*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic / Q000235:genetics*; D011972:Receptor, Insulin / Q000235:genetics*; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D014280:Triglycerides / Q000097:blood
D014280:Triglycerides; D011972:Receptor, Insulin