DOES IGF-II GENOTYPE PREDICT BMI AND BODY FAT IN MEN AND WOMEN ACROSS THE ADULT AGE SPAN?

Abstract

O'Dell et al. (Int. J. Obes. 21: 822, 1997) reported that an insulin-like growth factor-II (IGF-II) gene variant predicts weight, BMI and serum IGF-II levels. We investigated the association of IGF-II genotype with weight, BMI and body fat mass in 452 men and women across the adult age span (19–90 yr.) from the Baltimore Longitudinal Study of Aging (BLSA). Subjects were genotyped for the Apal IGF-II polymorphism and categorized as exhibiting the GG (n = 218), GA (n = 180) or AA (n = 54) genotype. Because IGF-II is imprinted in humans, we compared directly GG vs AA individuals, with age, sex and/or height covaried. Phenotype measures included weight, BMI, and DEXA-measured fat mass. Serum IGF-II levels were also measured in 90 men from BLSA (47–89 yr.). Our results indicate no association between IGF-II genotype and either weight (GG = 78.2 ± 1.1 kg vs AA = 78.7 ± 2.0 kg), BMI (GG = 26.3 ± 0.3 vs AA = 26.8 ± 0.5), or fat mass (GG = 24.8 ± 0.7 kg vs AA = 26.8 ± 1.2 kg) between genotype groups. Serum IGF-II levels were also not associated with IGF-II genotype. Our results are in conflict with those of O'Dell et al., and indicate that IGF-II genotype does not predict weight, BMI, fat mass or serum IGF-II levels in healthy men and women across the adult age span. Supported by AG05893, AG16205 and Intramural Research Program NIA