PLASMA LIPID LEVELS AND THEIR RESPONSES TO ENDURANCE TRAINING: ASSOCIATION WITH AN IGF-I GENE POLYMORPHISM

1908 The aim of this study was to investigate the relationship between a DNA (CT)n polymorphism in the insulin-like growth factor-I (IGF-I) gene and lipid and lipoprotein levels before and after a 20-weeks endurance exercise training in 776 subjects from the HERITAGE Family Study. Eleven lipid and lipoprotein phenotypes measured at baseline (B) and after training were adjusted for age and fat mass within each sex by race groups, with further adjustment for baseline values for the changes (D) in phenotypes. The polymorphism was genotyped using the PCR method (12 alleles, allele 189 showing a frequency of 0.71 in Caucasians, and 0.53 in Blacks). In Caucasians, significant linkages (p<0.001) were found between IGF-I gene and ApoA-I. Weaker linkages were also detected for HDL-C and HDL2-C (p=0.04 and 0.02 respectively) in Caucasians. No significant linkages were found for TG, VLDL-C and VLDL-TG, and no significant linkages were found in Blacks. In association studies, 189/189 bp homozygote women of both races showed higher B ApoA-I levels than other genotypes (p=0.02 and 0.015 respectively for Caucasians and Blacks). The same results were detected for B HDL-C in women of both races (p=0.01 and 0.04), for HDL2-C in Caucasian women (p=0.03), and for B HDL3-C in Black women (p=0.03). In response to endurance training, D ApoA-I in Caucasian female 189/189 bp homozygotes was increased in contrast to other genotypes (p=0.04). In addition, the influence of IGF-I genotype on the response of ApoA-I to training was modified by the degree of fat mass lost in Caucasian females. The results suggest that the IGF-I gene is of importance in determining the levels of HDL-C, HDL2-C, HDL3-C and ApoA-I and in their responses to endurance training. Funded by multiple grants from NIH-NHLBI.