Apal polymorphism in insulin-like growth factor II (IGF2) gene and weight in middle-aged males.

In 1474 healthy Caucasoid men aged 45-65 y, insulin-like growth factor II (IGF2) Apal AA homozygotes showed a mean body weight 4 kg lower than Apal GG homozygotes (77.6 +/- 10.9 kg vs 81.6 +/- 11.5 kg, P = 0.003) with heterozygotes (GA) intermediate (80.1 +/- 11.9 kg). The mean serum IGF-II concentration in 44 Apal AA individuals was significantly higher than in 48 Apal GG individuals (683.3 +/- 146.9 ng/ml vs 614.0 +/- 124.0 ng/ml, P = 0.01). An INS Pstl polymorphism showed no association with weight and it was also found to be in minimal linkage disequilibrium with the IGF2 Apal site (coefficient 0.016). The IGF2 Apal AA genotype is therefore associated with lower mean body weight but higher serum IGF-II concentrations than the GG genotype. Apal GG homozygotes incur a 1.67-fold risk of pathological Body Mass index (BMI) (> 30 kg/m2) compared with AA homozygotes.