Type II diabetes mellitus and polymorphism of insulin-receptor gene in Mexican Americans.
Resistance to insulin action is a well-established feature of type II (non-insulin-dependent) diabetes and is believed by many to contribute to the etiology of this condition. We therefore characterized restriction-fragment-length polymorphisms of the insulin-receptor gene with the restriction enzyme Rsa 1 in 242 Mexican Americans and non-Hispanic Whites with type II diabetes and 202 age-, sex-, and ethnicity-matched control subjects who participated in a population-based study in San Antonio. Alleles of 6.7 kilobases (kb) (A allele), 6.2 kb (B allele), and 3.4 kb (C allele) were identified. The C allele was observed in Mexican Americans only, where its frequency among nondiabetic control subjects was 17.7%. Diabetic Mexican Americans were twice as likely as control subjects to be homozygous for the C allele. The crude odds ratio for diabetes in CC homozygotes compared with the other two genotypes was 2.22, although this result was not statistically significant (chi 2 = 1.57, P = .21). The Mantel-Haenszel odds ratio, adjusting for age, however, indicated a 4.71-fold increased risk of diabetes among Mexican Americans with the CC genotype compared with Mexican Americans without this genotype (chi 2 = 5.38, P = .020). The age of onset of diabetes was also slightly younger in CC homozygote cases (45.4 +/- 9.2 yr) than in CX or XX cases (47.7 +/- 9.0 and 48.6 +/- 9.6 yr, respectively), although this difference was not statistically significant (P .467).(ABSTRACT TRUNCATED AT 250 WORDS)
Raboudi
S H
SH
Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston.
Mitchell
B D
BD
Stern
M P
MP
Eifler
C W
CW
Haffner
S M
SM
Hazuda
H P
HP
Frazier
M L
ML
D000328:Adult; D000483:Alleles; D004247:DNA / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology / Q000235:genetics*; D005838:Genotype; D006630:Hispanic or Latino / Q000235:genetics*; D006801:Humans; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length; D011972:Receptor, Insulin / Q000235:genetics*; D012307:Risk Factors
D004247:DNA; D011972:Receptor, Insulin