K121Q PC-1 gene polymorphism is not associated with insulin resistance in a Spanish population

Objective: To investigate the effect of the K121Q plasma cell membrane glycoprotein (PC-1) polymorphism on the components of the insulin resistance syndrome in a population-based nationwide multicenter study in Spain. Research Methods and Procedures: The subjects of the study were 293 nonrelated adults (44.7% men and 55.3% women) ages 35 to 64 years randomly chosen from a nationwide population-based survey on obesity and related conditions, including insulin resistance and cardiovascular risk factors. Obesity-related anthropometric measurements included blood pressure, oral glucose tolerance test, lipid profile (total cholesterol, high-density lipoprotein- and low-density lipoprotein-cholesterol, and triglycerides), plasma leptin, insulin levels by radioimmunoassay, and insulin resistance (homeostasis model assessment). K121Q PC-I genotypes were determined by restriction fragment-length polymorphism-polymerase chain reaction. Results: Overall Q allele frequency was 0.14, with no differences between obese and nonobese individuals (0.15 vs. 0.13). After adjustment for sex, age, BMI, and degree of glucose tolerance, the Q allele was associated with high plasma leptin and triglyceride levels, but not with insulin resistance. Discussion: The results showed that the K121Q PC-1 polymorphism in the Spanish population has no significant impact on insulin sensitivity.