Associations among IGF-1, IGF2, IGF-1R, IGF-2R, IGFBP-3, insulin genetic polymorphisms and central precocious puberty in girls.

BACKGROUND

Insulin and insulin-like growth factor (IGF)-1 coupled with growth hormone helps control timing of sexual maturation. Mutations and variants in multiple genes are associated with development or reduced risk of central precocious puberty (CPP).

METHODS

We assessed single nucleotide polymorphisms (SNPs) in the IGF-1, IGF-2, IGF-3, IGF-1 receptor (IGF1R), IGF-2 receptor (IGF2R), and IGF -binding protein 3 (IGFBP-3) genes, and their association with demographics and metabolic proteins in girls with CPP. Z-scores of height, weight, and body mass index (BMI) were calculated with the WHO reference growth standards for children.

RESULTS

IGF-1 serum levels of CPP group exhibited a higher correlation with bone age, z-scores of height and weight, and luteinizing hormone (LH) than those of control group, regardless of BMI adjustment. In the CPP group, height was associated with IGF-2(3580), an adenine to guanine (A/G) SNP at position + 3580. BMI in the CPP group was associated with IGF-2(3580), IGF1R, and the combinations of [IGF-2(3580) + IGF2R], and [IGF-2(3580) + IGFBP-3]. Body weight in the CPP group was associated with the combination of [IGF-2(3580) + IGFBP-3] (p = 0.024). Weight and BMI were significantly associated with the combination of [IGF-2(3580) + IGF2R + IGFBP-3] in the CPP group. These associations were not significantly associated with z-scores of weight, height, or BMI. The distribution of these genotypes, haplotypes, and allele frequencies were similar between control and CPP groups.

CONCLUSIONS

These known SNPs of these IGF-1 axis genes appear to play minor roles in the risk for development of CPP.