Insulin VNTR and IGF-1 promoter region polymorphisms are not associated with body composition in early childhood: the generation R study.

OBJECTIVE The objective of this study was to examine the associations between insulin gene variable number of tandem repeats (INS VNTR) and insulin-like growth factor 1 (IGF1) gene promoter region polymorphisms with body composition in early childhood. METHODS This study was embedded in an ongoing prospective cohort study. Growth in early childhood (body mass index, total subcutaneous fat mass and waist-hip ratio) was assessed at birth and at the ages of 6 weeks and 24 months. DNA for genotyping was available in 738 children. RESULTS The genotype distribution of the INS VNTR gene was I/I 50.4%, I/III 40.4%, and III/III 9.2%. IGF1 genotypes were categorized in the following categories based on their 192-bp allele: homozygous (wild-type) 43.1%, heterozygous 45.8%, and noncarrier 11.2%. No differences were found in body mass index, total subcutaneous fat mass and waist-hip ratio in early childhood between the three groups for both the INS VNTR and IGF1 genotypes. We also did not find interactions between these genotypes and gender or birth weight on the effects of body composition measures. CONCLUSIONS Our results do not support previous studies showing associations between INS VNTR and IGF1 promoter region polymorphisms with body composition in early childhood.